The Big Problem With Modern Manual Transmissions - Rev Hang

[@EngineeringExplained]

Hello everyone and welcome! Today is my KZbin Birthday, and Engineering Explained is officially 9 years old! Thanks for joining in, I really appreciate it! As for the video, I have wanted to make a video on rev hang for a long time, but wanted to make sure I had it right. I've discussed this with numerous powertrain engineers, read through academic literature that relates to the subject, and boiled it all down in this video. Quite excited about this one, hope you enjoy!!

[@adarco99]

Thank you for helping us understand complex systems and why they're used in the first place!

[@RenanBorges96]

You're a maaaad man Yayson!! I'm watching you since the very first day of my mechanical engineering college degree here in Brazil. You totally deserve the best!!

[@mattsteelephoto]

Happy Birthday EE and congrats Jason!!!

[@SE3552]

Been here since the smaller whiteboard.

[@chandreshverma6419]

Happy Birthday EE🎂 And a big congratulations to Yayson!!! Just love your videos.... Lots of support from India☺

[@NorthernChev]

It doesn't matter how hard or soft I shift, there's still a jerk in the driver's seat.

[@johncary4302]

My passengers get jostled around like a friggin washing machine

[@TheTman9898]

@pete smyth quality comment 😂😂

[@fromisheon4867]

And old people like my dad and mom think I don't drive stick very well because of the jerkyness. And my mom thinks my dad is better. I think I am way better than him.

[@OscarSabaterCruz]

if you want to avoid jerkiness, use more clutch. But to avoid burning through it you should be able to time correctly the gear, soft releasing of the clutch and rpm, and it'll go smooth as hot butter.

[@2Str0k3]

@@OscarSabaterCruz You dont need to use more clutch to shift smoothly. It depends on what you'r engine rpm's are when you release the clutch. You can shift basically shift smoother than most automatics if you know how. And without sliding the clutch. And there is no need to change gears like driving a freaking race car. Rev hang can be compensated with slower shifting. Its not like you lose any time shifting slightly slower in normal driving. All cars are different to drive and its only a matter of getting adapted to the vehicle you're driving.

[@lancepharker]

I had a throttle body freeze up while going down a hill in winter, now THAT was some rev hang...

[@zaceryhammond1144]

Oh geez 😆

[@Alex462047]

I'll bet.

[@MrMiatalover]

Was it a 76 Rabbit? Mine was.

[@sconescrewdriverson]

Might be because of the increased fuel needed to start and keep engines running in winter... could also be a leaky injector. Get your engine checked out.

[@bryanmasis1595]

Drive by wire?

[@abhisheksoni2980]

I surprisingly understood everything. And I'm a dentist. As they say.. if you can't explain it to a ten year old, you don't probably understand it yourself.

[@droplifter3435]

All I keep imagining, is a reverend throttling a dead body, and being sentenced to hang.

[@Tom_Hadler]

Never met a ten year old dentist before. Well done

[@glenwaldrop8166]

@@Tom_Hadler beat me to it. I'd wager he's probably pretty good at understanding most things if he's a ten year old dentist.

[@dehypnotizerz]

​@@Tom_HadlerJudging by his login, he's from India. Everything's possible there 🤐

[@meetankush]

@@dehypnotizerz The founders of the internet started it in the hopes of making the world a better place to live. They forgot to account for your existence.

[@Eurosport.Automotive]

I’ve seen mechanical throttle bodies with a “cammed” lever so that the airflow increase is more proportional to input at the accelerator pedal.

[@joelrolo1915]

thats really interesting, thanks for sharing!

[@aitorbleda8267]

I think that most have that.

[@donhappel9928]

@@aitorbleda8267 Yes; I was surprised he left that detail out. I was all but shouting at the screen over it.

[@pbakker]

I believe Porsche used that in their older (?) cars. So that the driver gets a more aggressive feel when applying the accelerator.

[@lolbuster01]

Honestly I haven't seen many that don't have a cammed lever.

[@Rickshaw302]

You totally nailed it. I used to do emissions testing at Ford back in the 80s when cars were transitioning to 3-way catalyst necessitating, prior to EFI, feedback carburetors to attempt to control to stoich AFR. But with carbs there were all sorts of AFR excursions during transient tip-in tip-out modes, and on a tip-out, all the wet fuel clinging inside the intake manifold suddenly vaporized and sent this huge HC spike which blew through the oxidation catalyst. Remember dashpots on the carburetor? This slowed the closing of the throttle to it's idle setting to attenuate the fuel vaporization rate, the first form of rev-hang. But even on my 93 Mustang with EFI and cable actuated throttle, it has the annoying rev-hang, but this is the idle speed control valve acting, like drive-by-wire throttle, to bypass air to achieve the same emission control goal. Just some retro perspective to ponder. The guy below said it succinctly, 'it's to control emissions'. Today, there are regulations to be met, vastly more stringent than the 80s. Give credit to the engineers that achieve them and build engines like the Coyote, LT6 and Hellcat.

[@HECKproductions]

good thing that my throttle is cable operated then again my scooter doesnt have any gears...

[@JPRTonundFilmstudio]

Probably has a carburetor as well, doesn't it? Would be interested to see these curves of lean/rich mixture when closing or opening the throttle valve of a carburetor-engine :)

[@stevepowsinger733]

HECKproductions a Cushman possibly. Slowest scooter ever developed.

[@Marcony-R2D2]

My scooter had cable operated throttle. It snapped @120km/h and stayed wide open when I had to brake for a corner. I'm alive only because I reacted fast and hit the engine kill switch

[@billbergen9169]

@@Marcony-R2D2 Learn to check cables! I had a drywall jack fall on my head because of a faulty cable.

[@nicholaslau3194]

same, but i dont even have a car

[@RenanBorges96]

4:07 This engine is super clean.

[@cerealkillr12]

3:34 SUPER CLEAN

[@jGRite]

sUPeR ClEaN

[@lowtus7]

You failed to mention that cable driven throttles usually have some mechanical non linearity built into them. If you look at the part the cable goes around, you will notice it's oval. Otherwise good video. I have just converted my car to drive by wire with an aftermarket ecu, and can confirm no rev hang, it's all in the tuning, as you say, it's a deliberate thing built into Oem cars, not a limitation of the technology in general. Electronic throttle, when you can set it up yourself is awesome.

[@petebusch9069]

We use different throttle cams on our motorcycles to change this.

[@Past10Performance]

​@@petebusch9069ya I'm really surprised a channel of this quality didn't mention that throttle cams are almost never actually just round and are almost always oval or egg shaped for this exact reason

[@Diddy_Doodat]

I would love to see you take a shot at tuning a car. With all of your knowledge, that may be interesting to watch.

[@XmaXma6]

He had an s2000 which he supercharged (and then sold for the mx-5) and a integra he tried a small series of build vids on, but it got stolen or something.

[@BeaverLakeMotorsports]

@@PushyPawn What fantasy world do you live in? have you ever heard of flash tuning? it exists for pretty much everything out there.

[@CalculatedRiskAK]

@@PushyPawn In current times, "tuning" is a word that refers to ECM/TCM recalibration via flashing the memory. We aren't talking about the primitive engines of yore.

[@yaris5150]

@@CalculatedRiskAK right lmao? like this isn't obvious information already/even inconsistent with the video, having "modern" in the title

[@cbr7170]

@@PushyPawn Jesus you literally have no idea. First of all, there is the option of flashing an ECU. In addition with oder mods like airbox/filter, exhaust etc. it can definitely lead to a serious gain in power. Also there is other tuning than engine tuning.

[@tolrem]

Every video I see like this just gives me another reason to hang on to my 90's cars.

[@matufujiwara7493]

welcome to club. im still driving 1977 carb car with only electronic device being radio. ill take old car everyday over these pieces of junks they call cars nowadays. imo theyre more like robots. you cant even do what you want, emissions emissions emissions everywhere

[@spackle42]

I know, right? I kept my clydesdales and carts, and I never experience rev hang!

[@tostadorafuriosa69]

Ultil they are so old they fall to pieces.

[@fer1306]

Yea stay in a cave

[@frizzen]

This isn't a new problem. 1975 VW Rabbit had major rev hang. It had an "anti-backfire valve" that held the throttle open. It was pretty awful. Without the valve, it backfired EVERY shift.

[@erich6860]

I would love to see a modern engine with today's materials and tolerances ran with all mechanical/carb then converted to all electronic and see the actual mpg differences and emissions.

[@atarvhegde5210]

Well EFI does help. I can't say the same about Electronics throttle body

[@erich6860]

@@atarvhegde5210 All these things "help", I just wonder how much. 1-5-10 mpg. Something like a mid 70's slant 6, remade with all modern tolerances and materials comes to mind. That thing got nearly 20 mpg at 3.7L,,,, just at 125 HP, but it was a loose motor.

[@jeevanrohtak5126]

Eric man , you gotta come and live in the 21st century man

[@erich6860]

@@jeevanrohtak5126 Jeevan man, you gotta pay attention to what I said. I shall explain it to you, since you seemed to have missed it. I am curious how much fuel efficiency is in the electronics, vs the upgrades machining technology and materials. So, in short, pay attention to what I was saying, and not what ever thought just possessed you to type what you did, man.

[@michaelbenardo5695]

There would be no way to make it streetable unless it had a much milder camshaft and smaller intake ports. Also, today's emissions standards almost require a dry intake manifold. That's why no throttle body fuel injection. It wets the intake just like a carb does.

[@CyberPitz]

I've had this for the first time with my Evo X and I thought I was just being a terrible shifter! I tried to explain it in the evox forums and everybody just said I was shifting wrong. Glad someone finally got this fully explained out, it was fantastic!

[@NathanaelNaused]

If you've driven older cars or a different model that drives properly then coming to this will frustrate you a lot.

[@centuryhelix8727]

I had the same exact thing happen to me in the Scion tC community. Everyone told me that I was either shifting wrong or Needed to get a lightweight flywheel 🤦‍♂️ I just wanted someone who could tune it out

[@qleap99]

Evo X also and first time I experienced it as well. Wondering if it can be tuned out during the performance tuning process.

[@NateFanning]

The answer to any modern car problem: “it’s to control emissions”

[@meemdoggoriginallongdrink]

Ikr. It's quite ironic that 90% of the cars in sale are crossovers. Because they are sooo eco-friendly

[@jupitersailing6911]

Yeah but it’s understandable I mean at least they are trying new technology to help save the planet

[@TheSupergunman3000]

@@jupitersailing6911 I think it does not make any difference, whether you want to decrease emissions or not, it will not destroy a planet

[@breabanm]

and that's why we are going to shift to electric drive sooner or later, subsidized or not

[@JamesBrown-ux9ds]

Yes - and this is nice way to sell it to the public as: there is plenty more reason of course. For instance it is much cheaper and easier to have an additional cable in the harnees to to the engine, compared to the good old wire-able solutiion. And e-gas usually takes its data from a data-matrix in the cpu - data based on the manufactures measurements during vehicle developme'nt. But some of theses e-gas just seem to be bad quality, cheap plastic etc. and often don't last very long. And the production, distribution and installation of replacement parts is as well effort, harming the environment.

[@ghshrksidhc5460]

I don't know why I'm watching this, I can't even afford to fix the suspension in my 1993 Audi 80. Edit: As of last month, sadly she is deceased, had a crash at a car meet, front ended up totalled, wrecked intercooler. Spent some good years with her, Rest in Peace.

[@toottootfuckshit8755]

B4 2.0L?

[@ghshrksidhc5460]

@@toottootfuckshit8755 B4 1.9 Turbo Diesel

[@toottootfuckshit8755]

I have the 2.0

[@bermchasin]

F

[@mhagnew]

The people are supposed to meet, not the cars! Sorry to hear about your 80. I had an abusive relationship with a 4kq.

[@jetmirberisha8201]

Few things are more satisfying than responsive revs, up or down. Rev hang ruins the manual experience

[@TheExplosiveGuy]

Got that right. I want my car to jerk left when I stomp on the gas, and jerk right just as fast when I let off. A motor should decelerate just as fast as it revs up...

[@jscott1000]

I agree. Some modern manuals will prevent the engine from stalling or even restart automatically. Enough. Make manuals actually manual.

[@gainzplz4028]

Right? Idgaf about emissions on my weekend car, I just want it to feel like a real car. Not like these babysitter cars that have 100 different electronic systems on them (like ESC) making everything feel numb and dull.

[@QualityDoggo]

They should keep it electronic for automatics because of the listed advantages (especially as the sensors/computers get more complex they can boost efficiency) whereas manual should be a simpler mechanical system the way people understand (at the cost of some engine-level controls that are only possible with the computer system anyways) Plus someday there's gonna be a significant split to self driving cars where there is no human-shifting or "pedal feeling" anyways

[@QualityDoggo]

Gainz plz to be fair they have some advantages for performance too - humans only have so many limbs but the computer can control/monitor hundreds of points, but like he said it's up to how the computers are tuned/configured - most consumer cars right now are just meant for a smooth efficient ride... they should give more options to have either manual or power/control-tuned systems (interestingly, Tesla cars have some of this: because the motor is entirely electronic they can accurately control stuff like how much power is pumped into it at different speeds - apparently destroys your efficiency but gives crazy acceleration especially at low speeds ) Definitely need more modern cars that keep the "fun manual" experience one way or another though :/

[@rohanhay7]

Can we just be happy that at the very least manual is still in some cars, we need to appreciate this more.

[@snowysysadmin59]

That wont be for long unfortunately

[@6six9nine74]

@@snowysysadmin59 Mine will never leave its body

[@moistdragon3200]

I managed to get a 2012 Chevy Sonic with a 5 speed Manuel and I barely feel a jerk.

[@paul-4872]

Ford just announced a new manual (the bronco) not that long ago hopefully this means they come back if it’s successful

[@moistdragon3200]

@paul. Here's hoping

[@vickauder7115]

Literally couldn't be a more intuitive and thorough explanation. That was an amazing video.

[@BASvist]

Oh so that's why my car sometimes jerks when I shift and keeps the revs longer than older cars when clutched in... Good to know :)

[@dhoffnun]

Yep. I just spent the past handful of months learning that the hard way, and then this video comes out. I learned to drive on a throttle cable - and when I got a newer manual it took me forever to drive it smoothly... and I have to wait sooo looong between gears. Yes yes fuel economy but I WANNA DRIVE

[@saltdaemon4453]

yep quicker, more difficult clutch jobs.

[@desposyy]

I just thought 5 years off the road had just made me rusty

[@umairumair1680]

When u shift up for example from 2nd gear to 3rd gear do not fully release accelator paddel try to keep u r car in 1500rpm when shifting up u r gear .. in this case ur car engine will be in motion and u r car will not jerk by releasing cluch

[@hyakinthos_0902]

I was thinking iam shifting my car wrong all this time lol

[@lincoleobenitez9843]

Sometimes I fail to understand half of what he's talking about, but despite my ignorance I always appreciate this man's passion to explain everything and how much he knows his stuff. Happy birthday btw, best wishes from Argentina

[@sirizoc9870]

Hey Jason, I get your point, electronic throttle bodies are good for efficiency and drivers who don't care how their car actually drives, but, there is one big BUT. Then I drive my car and press the pedal, i don't measure how much in percentage i press the pedal or how much torque I get from the engine, then i press the pedal i want CONSISTENT response from pedal, i don't want 20% torque at 20% pedal input, i want 20% throttle body open - direct control. Because with todays cars i hate that detached feeling, then i press in full pedal and i feel that throttle bodies are not opened to the fullest, sound alone gives that away and saddest part is sold my 1992 volvo 940 which had mechanical throttle bodies and now all modern cars have electronical throttle bodies :/. I don't care about efficiency because i love the feeling you get then you get pedal in 'right' position for your speed. Maybe you could make an episode about switching from electric to mechanical throttle bodies ? is that possible ? is that hard ? Maybe an experiment with your own car and a little drag strip ? ;)

[@Lostsage01]

Dude... I’ve been wondering about this for YEARS with my car and never thought it had anything to do with the drive by wire throttle, just the stock flywheel. Thanks!!!

[@davidpistek6241]

Compared to my s10 or 10 speed big trucks my civic si is not as smooth due to this I'm not as consistent

[@nerdyengineer7943]

My vehicle has a mechanical throttle, but I have lots of rev hang. I bet it's using the idle air valve to accomplish it.

[@permabulk1454]

@@nerdyengineer7943 me too. My 04 gto doesn’t have rev hang but the initial grab into 1st gear has always been the most finicky I’ve ever felt in a car. I had a 2001 cavalier z24 manual 5 speed (obvi with fwd and electronic throttle) and for some reason engaging first in that car was way simpler than the gto. Any other gear from second to 6th is completely normal (tho a bit slow due to the weak clutch/slave from the factory) but something about 1st gear in it with the drive by wire creates the most odd feeling 1st gear engagement

[@alexvillalobos7137]

@@davidpistek6241 lol Im in the same bag. My s10 extreme drops the rpm’s fast so I can shift a lot faster. My type r…. The rims take forever to drop. I don’t go hard in the car but when I do I might bang gears. 6000+ rpm’s can’t be good for my clutch. Smells stronger than any car I’ve had. My s10 or Camaro ss have never smelled like burnt clutch while banging gears.

[@michaelbefumo-qg7ji]

My 08 Ford expedition with drive-by-wire 1.4 low it changes the throttle input so if you bounce on the throttle it won't be jerky and full it changes the throttle input so if you bounce on the throttle it won't be jerky in low range four-wheel drive smooth

[@BigStreams_]

Rev hang kills the driving experience for me, and it’s why I will soon be selling my manual Crosstrek. It just feels like such a chore to drive.

[@EngineeringExplained]

Haha, the Crosstrek isn't exactly a great representation of a fun to drive vehicle, but it's an excellent car. I'm happy with the manual.

[@truantray]

Crosstrek...the ultimate enthusiast driving vehicle.

[@joelhenderson3723]

I have a manual Honda Fit, and while I'm not thrilled with the shifting experience, I wasn't expecting much- it's an econobox, after all. Even with the complaints, though, it's slightly more fun to drive a manual Fit than a CVT, and more important to me is the fact that any extra physical engagement helps keep me that much more alert.

[@DanielSanPedro]

I feel the same way. I despise my Honda HR-V because of it. But now I can be at peace with it. But the first chance I get to burn it with fire... errr I mean sell it and get something better, I will

[@fabriziom]

Realized with many cars with rev hang that if you lift off the gas pedal before pressing the clutch it usually works much better. Completely counter intuitive but I tried this on many cars and it seems to work. Of course for race starts it doesn't work and shifting is awful 😊

[@mikeking2k6]

What’s crazy is, I had no idea what I clicked on and was just trying to see another informative manual trans video. After watching, I realize that this situation implies to me so directly and I had no idea it was happening. My last car had so many emission problems to the point I dreaded my two year testing period 6 years straight. I see now I had a serious top out problem and my new car definitely solves the issue.

[@oldaccount-j8j]

Me: presses pedal to 25% hoping for 50% air Gets 25% air. :O

[@whoknows1631]

Windbooster throttle controllers

[@Nexfero]

4:08 look at that SUPER CLEAN intake hose

[@SpeedHunter_9]

Thought no one's gonna notice that LOL

[@adamrozman]

Someone’s watching Chris fix videos 😉

[@gabrielv.4358]

bahahaha

[@cooperised]

The first time I drove a "modern" car with an electronic throttle body I just stalled it the whole time. Muscle memory meant that I was used to using only a small amount of pedal travel when letting out the clutch to pull away. My conclusion? The "ideal" throttle response is whatever throttle response you're used to...

[@zsteinkamp]

Makes me remember looking at my BMW E46 shop manual and seeing the electronic throttle circuit labeled as "Torque Request". We know who's the boss now...

[@SonsOfLorgar]

*Skynet sees you*

[@russlehman2070]

It ain't the driver. With antilock brakes, traction control and electronic throttles, the computer's in charge. Don't get me wrong: that stuff works amazingly well most of the time, but I do find that the traction control especially on occasion will cut the throttle back to nothing at the worst possible time.

[@pauldzim]

Thank you! After I got my manual BMW, I thought I had forgotten how to drive stick because I kept getting weird revving when I was shifting. Now I know what it is!

[@L39T]

I too experienced the same thing. It is still driving me nuts after a year of owning the car

[@danielbelousov742]

@@L39T I was learning to drive stick on a new Subarua and was pissed that I have to wait for something to happen when realising the clutch.

[@wim0104]

just give it some gass when you let the clutch bite. or a lot of gas; the 6 speed subaru transmission is pretty strong now :-)

[@spralwers]

Many manual BMWs also have clutch delay valves. Look up if yours has one and get it either removed or replaced with a valve that doesn't delay.

[@meister.leistung]

Idk why I'm watching this, my car is carbed.😂

[@jeredek9901]

Cus it's fun

[@Dizzle13]

Bro my exact thoughts as I clicked on this

[@ajj9703]

W

[@bongboi2831]

I dont like my carb so im gettin a throttle body injector

[@桜島めい]

I don’t know why I’m watching this, I can’t even afford a car.

[@ThatGenericCanadian]

I've always heard that Subies had rev hang because it helped emissions and I'd always been curious as to how dropping the RPM slowly would do anything, so now I know! Great video, thanks!

[@wim0104]

the software throttle is also a pain for hill starts with cold engine (stickshift 2011 outback)

[@RidinDirtyRollinBurnouts]

This is a lot of cars, the EGR feeds back into the intake and the idle-bypass will be open during liftoff so lots of rev hang. Its the same bypass that makes your engine idle high in cold starts.

[@catinthehat5140]

They fixed this in the new wrx

[@twinboost9325]

My SF Forester has the most obvious hang of any car I've owned, it got more pronounced when I cleaned out the intake and Idle air solenoid, I thought I may have busted something at first.

[@riley1733]

I drove two Subaru's and to my knowledge, neither of them had it. Both were standard and one was an Impreza and the other one was a WRX. I have a Honda Civic Si Coupe now and that car has massive rev hang. I haven't experienced it in a Subaru yet to my knowledge but I know Honda cars have it in some of them. It's really noticeable in mine if you look at the rpm's closely when you're shifting the gears.

[@TheGardenSnake]

On one of my carbureted motorcycles it has different cable cams to change the rate the throttle is open in relation to the grip. Still if you wack it to WOT it’s still open but it does help make the throttle position to power out put more even. Also on fly by wire motorcycles the slight delay in throttle response is really noticeable. Every time I get on one it takes a few minutes to get used to it. On motorcycles where you’re so connected to the machine and road the fly by wire is not my favorite thing. I believe they can make it better and throttle hang has never been an issue I’ve noticed on them. Could be due to the ITB that motorcycles have.

[@K0nst4nt1n96]

Jake TheGardenSnake i have ridden newer bikes where you dont really feel the delay but older bikes with e throttle do really feel different. Also carb vs no carb.

[@jmmycnnll]

I was thinking the same thing. Just take a cable cam that is elliptically shaped and it would start opening slowly and thereby straighten out the torque/throttle position curve. Cool to hear that they are using that on motorcycles!

[@jamesmoechnig3855]

The carbs on the old bikes I've messed with have a vacuum-regulated venturi downstream of the throttle plate. This is essentially a gate valve that restricts airflow like the throttle, but for the purpose of maintaining uniform air speed through the venturi to ensure consistent fuel draw and atomization. I haven't ridden a motorcycle with electronic throttle, but I would expect any delay to be disturbing.

[@xXdatkid411Xx]

Hey, Jake! Wanna say some cars have the same "cam" on the throttle shaft.. love the vids!

[@jeffbrownme2]

Love your mt07 series Jake, but I couldn't get over the jerk throttle response of mine. Got a cbr650r. The jerk is still there but much more maneagble in a smooth 4 cyl.

[@gregkimura5906]

Excellent description! The other day, I drove a 2018 Jeep Wrangler with a manual and I noticed the rev-hang and the rpm being too high when I hit the next gear. I drive an older Alfa Spider that has no rev-hang and I can feel the rpm match as I up shift. With the Jeep, I was always at too high rpm. I owned a 2017 Toyota Corolla iM and I also noticed the rev-hang. I thought it was due to how freely the motor revs. Now that I've watched this video, I understand the process. Thanks again for another excellent video!

[@vasilis23456]

Imagine this: carburetors would actually fix the throttle tip in and tip out problem. I mean there's a million other problems it comes with but it fixes the problem.

[@matufujiwara7493]

he should make one big video about carburators. people these days are not familiar with carburators at all. with carburators once you let off throttle, the vactium starts sucking alot of fuel thru idle jet, and its massive amount that it sucks there. this was on old carbs so with old carbs you saved fuel when you went to neutral when letting off the throttle because it sucks tons of fuel when throttle is closed and rpms are over idling rpms. now newer carbs in the end had a valve that closed idle jet channel when rpms were over some certain rpms and throttle was fully closed. it opened back up if you press throttle or rpms droped below this certain rpm, but even this sort of system richens af ratio when coming off the throttle cuz it takes time to close that valve. but it did improve fuel consumption. now carb system itself always has problem that when you press on the accelerator the mixture is very lean for a moment, its that much that engine actually might want to shut off. this is mostly because some channels little bit flow down so the fuel isnt being sucked instantly and it takes slight time to suck them back up. to overcome this very lean mixture, all of the carbs (not including small scooter and chain saw carb cause their engine size is so small that theres no need for this thing) have a thing called accelerator pump which straight up pumps fuel into the intake while your pressing the throttle. full throttle press gives you about 10ml of fuel in the intake (this amount is taken from 1.5l inline 4 engine). now this fixes the problem of lean side, but it actually richens mixture alot so again you have bad emissions, so mixture with tip in and tip out is very rivh. now this accelerator pump is very useful for cold starting. you pump certain amount of fuel into the engine, and my car has started instantly even with -30degrees. something injectors never achieve cause they need first 2 rotations to get pressure up in fuel pump. carbs have, and always will have worse emissions compared to injection.

[@normanguzman417]

​@@matufujiwara7493 I live in Puerto Rico back on the 80's and we let our cars in 2nd or third gear going down the mountains to preventing boiling the brake fluid b y over heating the brake caliper going down hill for 10 minutes straight. When throttle body is close, it can't take more fuel than the idle jet will allow because there is a size restriction that won't allow more fuel trough the passage. therefore It will use no more fuel than what it will use for idle.

[@evan8tor21]

Rev hang is my excuse when I lose to ecoboost mustangs in my base model 2019 Mazda3

[@NathanaelNaused]

Although in a race scenario it would help you go faster because it's kinda like a half of a power shift. But I got the joke lol

[@evan8tor21]

Nathanael Naused i was able to keep up with my friend’s ‘01 Audi A4 with a v6 so it perhaps helps a bit.

[@RidinDirtyRollinBurnouts]

A first-gen Mazdaspeed 3 would put the hurt on an ecoboost stang

[@Wooskii1]

My dad has a 19 Subaru Impreza, It's the first car I've driven to have so much rev hang that I needed to learn how to drive "around" the hang. I thought it was just a crazy heavy flywheel! Great video! I'll have to check it out later lol

[@robertoarkenburg6652]

Thanks for sharing, I have an Impreza from the same year and this makes me regret getting the cvt version less.

[@KniteGraffiti]

yep 2017 impreza, i spent 300$ for tactrix cable + epifan subaruedit software to do a rev hang delete. probly the best and only engine upgrade i plan to make for the car but it made a huge difference and will save my clutch down the line.

[@ghanavaga5620]

still haven’t decided if he looks more like a 23 or 46 year old yet.

[@RWoody1995]

he is a 46 year old 23 year old.

[@babis8142]

his skin is super smooth for a 46 year old so he's probably much younger than that.

[@TheCostan]

Yes

[@ChrisHuppey]

He is like Tony Hawk. An old young adult. :)

[@tostadorafuriosa69]

isnt he like 30?

[@303nitzubishi4]

Excellent explanation. Bought my first brand new car in '98 and within a few months my shifts were buttery smooth and my r/t at the track was consistently

[@ozzy5368]

This was a great video! It made me do some thinking about a 2002 Mustang 4.6L I had years ago. It had terrible rev hang, but mechanical TB. The fix was to restrict the airflow of one of the lines connected to the TB by inserting a metal plug in the line with a small hole drilled in it to allow a small amount of airflow. I can only assume that this line was how the ECU added air when lifting off the throttle similar to what you explained here. By restricting that airflow, the rev hang was reduced.

[@dozacqt]

I love watching these videos on my lunch breaks lol. Everyone assumes I’m taking an online math class or something lol

[@SquishyZoran]

I’m doing that right now!

[@LightningSe7en]

Lol on my lunch break too

[@JeeveDaniel]

Me too lol

[@Brandon-xe2se]

Oh my lord I cant believe I'm not the only one

[@chrisdonnelly5904]

Well that's because you are LOL

[@rjbiker66]

I seem to remember that cars with a mechanical throttle would rev hang. There was a device called a dashpot that slowed the closing of the throttle thus reducing emissions.

[@NathanaelNaused]

Correct. Tune can help this or some physical mods to the valve.

[@jamiepeterson5646]

Yep, exactly right. I think the N/A AW11 MR2s used a dashpot, but the supercharged ones didn't, for example. On the other hand, all 3 cars I've had have had mechanical throttle bodies without a dashpot, so I don't think this method really took off until the electronic throttle bodies made it trivially easy.

[@russlehman2070]

Those were mostly on cars with carburetors. They tended to run very rich coasting at minimum throttle, which meant they ran very dirty. The dashpots I remember were vacuum operated and would keep the throttle from closing fully until the RPMs came down.

[@rogerpearson9081]

Yup, a mechanical solution but for the same reason.

[@rafetizer]

That was the big thing that stuck out to me when I test drove my '13 Civic SI. Compared to the RX8 I was trading in, there seemed to be substantial rev hang.

[@ChrisBrown-pz2gu]

There was zero rev hang on my RX-8

[@Conservator.]

4:09 So considerate of Jason to thoroughly wash his engine bay so that it’s super clean on this video! 🙏

[@emmanuelvazquez5036]

Looking for this!

[@DeenHameed]

Chrisfix has entered the building...

[@nopleaseno2515]

It’s not a grocery getter, it’s real world used.

[@Conservator.]

@@nopleaseno2515 I think you might have missed the joke. Have a look at the fragment in the video. Jason had left a message there. At 4:09

[@nopleaseno2515]

@@Conservator. oh yes you’re correct. Guess the joke wasn’t funny.

[@emperorSbraz]

all this "smoothing" the ECU does leads to the driver instinctively counter those effect with harsher throttle control, defeating at least partially the purpouse. :)

[@tiger12506]

100% real

[@JasonW.]

Airbus had this problem with early fly by wire and pilots over adjusting controls due to the lag between pilot inputs and airplane adjustments.

[@kristupasantanavicius9093]

I'm always flooring my manual and shifting low RPM, just so I can shift swiftly and smoothly O_O

[@CesarMartinez-wi7wc]

Yes

[@wigletron2846]

Yep

[@EDavis-bu7cx]

I had a carbureted vehicle with a vacuum dashpot actuator to accomplish the delayed throttle butterfly closure, too. That general system was not exactly uncommon toward the end of the days of carburetors on on-road automobiles. It’s also interesting the discussion about how one _could_ use electronic throttle control to make the relationship between pedal position and delivered power more linear. Why I think it’s interesting is that we don’t see that actually done. What we see instead is that electronic throttles are programmed to provide ridiculously overdone tip-in, because that makes people _think_ their car is really fast.

[@frankb3609]

Simple fix for rev-hang: install a tune. Installing Hondata's on my 2020 Civic Si completely changed the shifting experience.

[@GregBalzer]

Yeah. The rev-hang on my Si is horrible. Just horrible. Shouldn’t need to go aftermarket to fix - but it is what it is.

[@frankb3609]

@@GregBalzer Same was with mine. But after installing the tune, it's a completely different car and the gearbox is among the finest you can get. Getting rid of the rev hand alone made the tune worth it, the added torque and horsepower available once you press the sport button, a VERY nice bonus.

[@akihiko4036]

Same with my '06... the hang at 8300 was about a second long after you push the clutch in before I got a tune and it would rock back and forth

[@mgobluevictor]

Someday I will go down this path on my 2018 accord 2.0T with the 6MT. Rev hang sucks on this car, but I love every other aspect of it. I find that driving with AC on helps a bit, but with AC off it is awful.

[@alanprihoda7772]

I was wondering if a tune could help this. Might it cause problems during emissions testing?

[@ThisGuyTalks]

Me: EE has a new video out but the topic doesn't really interest me Also Me: Watches the entire video and learns more than I ever did in a day of school

[@teamjg277]

SAME!

[@the_kombinator]

LOL did you pay attention in that day?

[@ThisGuyTalks]

@@the_kombinator Absolutely not. This is all making sense now.

[@kyleklassen3660]

You know where he learned this stuff?

[@ThisGuyTalks]

@@kyleklassen3660 At a Holiday Inn Express?

[@DoctorHemi]

As the owner of a 2021 6.4L Hemi (all modern Hemi engines port-injected) Challenger with 6-spd manual, I appreciate this explanation very much! It explains the weird behavior on shifting that I noticed every since I bought the car. (All my previous manual-trans vehicles had mechanical throttle body.)

[@davidjteo]

Fuel not burning off when you let off the throttle to change gears? Flat foot shift. Boom. Fixed your problem.

[@Asymmetry0]

Cable throttle people, remember to check cable tightness, like a bicycle brake, will stretch over time giving you crappy throttle responses. Protune will eliminate rev hang if tuner knows what to look for.

[@homebrewinstrumentals7700]

cheers mate, I wasn't aware of this.

[@Iowa599]

That's not what he's talking about. A cable throttle is more responsive than an electric throttle, even if the cable needs adjusted. A loose cable doesn't really effect response, anyway, unless it is so loose that something else is obstructing the cable. It just allows the pedal to "wobble" more (move without doing anything), and at 100% at the pedal the throttle body won't be, so it goes slower. That all isn't a concern, because cable wear isn't a concern. A bicycle brake cable transfers a LOT of force, and unless the throttle is broken, but the throttle cable doesn't. It could, but it doesn't. It's "overkill", for the usual purpose, and that big to avoid bad problems. I just checked my 95 Jeep (with ~260k miles), it's still fine, and was never expected to be an issue, so the throttle cable is *not* adjustable. Some throttle cables can be adjustable, but for different reasons, and most cars don't meet the requirements to need adjustment. My motorcycles' throttle cables can by adjusted, but with those I'm opening between 2 and 4 throttle plates instead of one, in a wet environment (carb vs fuel injected), idle adjustment is needed (carb vs efi), with less movement (twist grip vs pedal), so higher cable loads.

[@sultanabran1]

who uses mechanical brakes on a bicycle?

[@HillBilly-1]

@@sultanabran1 everybody, I've never seen hydraulic brakes on a bicycle.

[@TravisTerrell]

That's what I was wondering. It sounded like something experienced tuners would have the ability to get rid of it in software.

[@philip4193]

Thank you for your detailed explanation; it explains to me why I experience so much frustration with my vehicle (Jeep Wrangler jk 3.8L V6 with 6-speed manual trans) and throttle hang. A major safety issue with the electronic throttle body is that when I begin going down a long steep hill or mountain pass in third gear for example from a lower speed with my foot off the gas and the brake pedal, the vehicle will initially coast down in a gradual manner with the tradition engine braking effect safely controlling the descent and avoiding me overheating the wheel brakes. However once engine speed increases to about 3000rpm or so as the vehicle's road speed picks up, the electronic throttle body will suddenly open up and "hang" as you described, causing the vehicle to suddenly surge forward with an increase in speed, forcing me to jam on the brakes in an emergency stop in order to avoid either hitting the car in front of me or (even more dangerous) suddenly speeding up into a steep bend that I'm using engine breaking to control.

[@johnny9066]

i’m with you man. i have a jeep with the same engine and the 6 speed. the rev hang absolutely sucks. it seems like the longer i drive the worse the rev hang gets. sometimes when i go to shift the RPMs don’t go down at all. im worried that this causes premature wear on the clutch as well.

[@robh693h4]

Great explanation. Wondered why I could never get my new Civic 6 speed to shift smooth, especially from 1st to 2nd.

[@GradeEhCanadian]

Same here first to second is the worse in my mazda

[@PurpleDinoRhino]

I have an 18 si, rev hang used to be really bad, but with a tune, it's pretty much gone. I also have a new clutch with lightweight flywheel.

[@dhoffnun]

Yep. The thing I miss most about my 6th gen Civic is its gearbox. It gave close to zero fux, and shifted as fast and smooth as you could. Meanwhile my new car with its bigger and more powerful engine is WAY more sedate because shifting is more like throwing a baseball to someone across the field than tossing it between your own hands.

[@_M27_]

Same on my dads '13 1.6D focus

[@jacobchaney]

Get a Ktuner or Hondata. You will have the option to turn rev hang off (as well as many, many other things). You can also turn on launch control.

[@roflchopter11]

The other way electronic throttles can improve efficiency with an automatic transmission is running the engine wide open in a higher gear, but still having pedal travel left to demand a downshift.

[@jamessilly6837]

Gas pedal down until you feel it's about to shift, get off the gas a little as it shifts, push the pedal down a little after the shift and instead of dropping rpm with the shift and slowly crawling back up you get a nice shift and then Rev back up quickly. Love that feeling in a moderate to low horsepower car just getting up to speed. Smiles per gallon haha

[@averyalexander2303]

That's true, reduced pumping losses.

[@roflchopter11]

@@averyalexander2303 Don't forget reduced frictional losses and accessory parasitic (hydraulic power steering, AC, iron losses in the alternator, belt, etc.) from reduced revs.

[@MeatPopsicl]

My V6 Tacoma: **Climbing a hill, losing speed** Don't worry, fren. We can lug up this hill in 6th gear. Me: **Applies 6% more throttle** My V6 Tacoma: Oh, I see you're asking for a tiny bit more torque. **DOWNSHIFTS TO 3RD, ENGINE SCREAMS!!**

[@xnopyt13]

MeatPopsicl on cruise control and on a hill my 4 speed Corolla would literally downshift to second at highway speeds

[@tomlangmusic9623]

Great explanation, thanks! My 09 Matrix 5 spd has rev hang in spades - it's like my throttle pedal movements are only a suggestion. From dead stop I often over-rev (really trying NOT to) and I'll bet that's chewing into any mileage/emissions calculation. My old Tercel with manual throttle linkage was smooth as silk.

[@soconnoriv]

But for real though, if I waited for my rpm to match for my upshift while going up a hill, my truck would literally be rolling backwards by the time the rpms matched.

[@doogetube6017]

Solution: shift into reverse

[@NathanaelNaused]

That's unfortunate and I know what you mean.

[@tloecoep2086]

@@doogetube6017 nice

[@gophop]

trucks also have very heavy flywheels because it helps with take-off when towing or offroading.

[@eliperez8481]

0:00 Oh my lord... graphs.. such beautiful beautiful graphs. this. this right here's is the reason I come to this channel.

[@tomcook8897]

This explains what I found. Second kid is having a hard time learning on our ‘22 civic 2.0L and keeps lugging at starts and rev hang causes issues at shifts. Turning off ‘Econ’ mode helped, but our ‘07 Vibe is way easier to drive smoothly.

[@MikeeCZ]

I always thought it was due to the heavy flywheel! I hate the rev hang on the ND :) Thanks for teaching me something new once again

[@EngineeringExplained]

I'm not sure what you're comparing against, but rev hang on ND is actually quite minimal. The Crosstrek is awful haha.

[@jesperviktorsson8027]

I cant even drive any car thats drive by wire, my shifts turn to dogshit compared to my e34 bmws

[@nickstephenson9482]

@@EngineeringExplained The rev hang is definitely less than some other cars , but it's still very noticable on my ND when compared to my NB. I thought there was something wrong with my car when I first bought it, but I have since gotten used to it. Great video as always!

[@AaronSchwarz42]

@@jesperviktorsson8027 practice makes improvement, surgeons are not born; they are made // hang in there :P you eventually master each setup ///

[@corynivens6510]

I experienced no perceptible rev hang on my ND. My GTI is a completely different story and took a while to get used to

[@hououinkyouma5539]

The Geo Metro was magnificent in its simplicity

[@MarkOrkenyi]

That is the one main thing i miss about my old Suzuki Swift..(same as the Metro there) :( That throttle feel/response is whats missing from every other car i've driven...

[@joesdiy4260]

I had 3-cyl metro with a 5speed. I absolutely love and miss that car.

[@MarkOrkenyi]

@@joesdiy4260 Imagine that with the 1.3 86hp version.. For it's 850kg :))

[@MalcolmCir]

...And got Hybrid-beating gas mileage, back in the early '90s. Incidentally, the only speeding ticket I ever got during that era was from flying downhill in a borrowed maroon 3-cylinder Geo Metro. 😁 You had to have driven one to understand.

[@rogrwi1co]

Finally, an EE video that explains rev hang. Thanks! Just a couple of questions: 1. Why does rev hang not exist when downshifting? It only mostly happens during upshifts. 2. My 2014 VW GLI with the 2.0 liter GDI engine had upshifts rev hang. However my port injected 2014 Corolla hardly has rev hang. Could rev hang be more pronounced with turbocharged engines? 3. Finally, how come lux brands BMW and Porsche do not have rev hang? How can they bypass emissions control? Thanks

[@alamos8]

Porsches and BMWs do rev hang too, you only have to search for in on internet. I have also read that yes, it is usually more pronounced on turbo engines, because, they have a more natural tendency to lower the rpm more slowly than N/A cars due to the turbine inertia, or so I think I have read

[@josephd152]

Finally know why shifting into second takes so long.

[@ianswitzer2915]

Also adding trickyness to the 1-2 shift is the fact that it’s also the largest gap and the revs have to drop the most. The gap is smaller for every successive shift, making rev hang less and less of an issue. Unless you drive a semi. Each of the 18 gears has exactly the same space. You learn a rhythm and shifting a breeze. Most truckers only use the clutch to launch, and then shift every other gear without clutching. But that’s a whole other video ...

[@Stasiek_Zabojca]

@@ianswitzer2915 I heard about shifting without clutch in semi trucks in America, but never heard about it in Europe. My dad who is a trucker here in Europe never heard about it. I think that a lot comes out of European truck's being made differently. But my dad now is happy, that he drives Volvo with new automated gearbox =) Btw, clutchless shifting is very popular in motorcycles. Especially if you are more kind of sporty rider. Even without quickshifters, which cut ignition while doing gearchange (and that lovely bang when fuel get's burned in exhaust).

[@Kalvinjj]

@@Stasiek_Zabojca if I recall, some (or many?) bike transmissions actually use dogs to engage the gears instead of the smaller teeth from synchronized gearboxes from most cars, so it happens easier. Those 18 gear 'murrican semis are a beast of their own too, they don't have synchros from what I know, 6 gears on each normal, high and low, pneumatic assisted. I remember asking some truck driver how it is that he operates them, from what I remember he said pretty often he skips quite many of those gears or the entire section (low, normal or high) and so on, or just wack the shifter to the side, and the air assist shifts to the next gear. It's also common to grind gears sometimes on those, no matter how experienced.

[@nicostenfors5690]

@@Stasiek_Zabojca Clutchless shifting WAS common in Europe back in the day when manual trucks were the only option. Synchronized transmissions were introduces quite early into trucks in Europe but the legendary Eaton-Fuller is not synchronized and requires clutchless shifting to work properly.

[@k5guy]

@@Kalvinjj Every bike uses dogs. Basically all sequential transmissions are dog boxes.

[@redbullbill8766]

This makes so much sense. I have a Miata and a crosstrek 32 years apart. Miata is mechanical and performs as explained. However sometimes I need to go full foot down on crosstrek to get performance I’m looking for

[@TheShamarski]

I noticed this happening when I first started driving. I developed the habit of letting off the throttle before I disengage the clutch. Haven't experienced it anymore Edit: or well, not perceiving it.

[@SketchRC]

Yeah I feel like if you own a car then you get used to it and it’s not a huge issue, I wonder if he just notices it because he’s reviewing different cars all the time?

[@theydidntnameme]

I've noticed this with rental cars. Throttle flat on the floor, then let off the throttle completely and... The car still seems to be accelerating for a moment or two

[@rurruth]

@@theydidntnameme put in sport mode, this enable the accelerator to react in a sharp mode, but normal driving consume less fuel because of these slow operation that discard some unwanted oscillations that our foot create (i.e. his mass and pot holes or uneven road)

[@ariv8585]

I did this also.

[@Redpsyclone]

Drove a 2008 manual with electric throttle for 9 years. This is exactly how I defeated the issue. Fuel deceleration cut off

[@crazypete3759]

Main takeaway is emissions regulations are ruining the driving experience....

[@huntermacdonald6431]

Yeah when hasn’t it been

[@randomvideosn0where]

@Planet Earth How much time is spent shifting in the typical car? Far more could be saved by increasing gas prices to encourage efficiency, and less travel.

[@xponen]

it ruin other driver's experience because that exhaust port will burp thick smoke without such emission control. Ewww... looks antique. "HC" (Hydrocarbon) is a polite way of saying "thick smoke".

[@crazypete3759]

@@xponen the only vehicles making "thick smoke" are the ones with diesel engines. I would actually like to see the data on how much more emissions are produced without the programing of the electronic throttle body.

[@TheBanjoShowOfficial]

Yeah but atleast pollution isn’t going to kill us as quickly

[@pedrosilvaproductions]

I bought just recently a Focus from 2020 having driven a Punto from 95 and I always felt that jerkiness while driving my new car. Thought I was the only one. What I found out was that I have to hold the clutch slighty for about a second before fulling releasing it, and that probably gives time f or the revs to go down. However, if I'm pushing the throttle and going faster I can change gears faster. Makes 100% sense on what you said, very informative!

[@r390gt1lm]

and i thought my car was broken, that clears things up

[@ariasdad]

Me too!

[@BlackPhillip666]

MAP OTS tune with a Cobb access point eliminated my rev hang, gave more power, and no lift to shift for my WRX. Best 600 bucks I've ever spent.

[@Jaymac720]

Some: MECHANICAL!!! Others: ELECTRONIC!! BMW: ValveTronic!

[@mojeimja]

...in service as usual :)

[@RonniePoleCasper]

Audi, mechatronic Bi*ch

[@timothyball3144]

Diesel: fuel throttled

[@an0nim11]

@@timothyball3144 btw i heard somewhere even some diesels still have something alike throttle body and it wasn't meant as intake flaps probably but im not really sure. Somebody knows something about it?

[@samehezzzat]

an0nim11 may be used for inducing some engine brake during the downhills.

[@treblemaker]

I leased a Jeep Wrangler Rubicon shortly after the JK generation came out. It had a 6-spd manual transmission mated to this dog of a V6 3.8L, and it had the most awful rev hang imaginable. I always thought it was due to a heavy flywheel, but now I learned that it's because of yet another singularly focused on emission initiative that doesn't consider the trade-offs. Thanks for explaining the engineering.

[@santiagoardilesgonzalez6451]

I used to remove my ABS fuse to drive in the race track, that made my throttle body more responsive to make a perfect heel and toe. Now I know why it worked.

[@aterack833]

What we need is for the clutch being pressed in to act like engine “neutral” and match the rpm on either side of the clutch, then when you shift the gearbox and there’s a surge up or down in clutch disk speed, the engine speed will follow it, if you had this and a power assist clutch with really strong springs, you may never need to replace the clutch other than when the springs wear

[@nocturnal101ravenous6]

There have been better systems implemented that don't use a clutch. Its cheaper for the manufacturer and more expensive for you as they are wearable parts which is why the clutch disc/clamp/bearing system is still used today. Audi developed a torsion manual system similar to how the AWD couplers work, its way more expensive and way more complex being scaled up and requires a bit more maint. than people are used to for a trans. the closest thing I have seen using a system similar is the Car(forget the name of it) with the TFG engine coupled with the electric motor, but typically you only see these high end designs in some Super cars but mainly Hyper cars like Mclaren and such that don't use conventional means of building a car.

[@parman01]

Mate what you're describing here is literally called rev matching and racing drivers do it all the time. You may too if you desire.

[@BigUriel]

@@parman01 Some cars have it. I think the Nissan 370Z was one of the first ones with it. I think it's a lot of fuss over nothing. Yes some cars are a little lazier dropping revs but when you release the clutch they'll always go where you want them to, if it causes a jerk simply release the clutch more smoothly. These are not usually "sporty" cars anyway, why would you be shifting gears in an SUV as you would in a sports car? It's clearly not the right car for that kind of driving style, the rev hang is the least of it.

[@mikegordon8178]

dual clutch/at input and output of transmission.

[@aterack833]

@@parman01 I think I was talking about automatically? I honestly can’t figure out my comment here

[@darin7220]

I've noticed rev hang in some newer 'performance cars' so bad that I wouldn't consider buying one, but I also notice it in my daily driver - a 2014 ford focus with a DCT. Scenario: On the freeway, far right lane in very slow traffic. Switch one lane to the left and stomp the gas to get up to speed before someone comes along and rear-ends me. Another driver in the right lane has the same idea and jumps into my lane but doesn't accelerate quickly forcing me to hit the brakes hard. When I switch from hard on the throttle to hard on the brakes it takes about 3 seconds before the engine RPMs start to drop and stops fighting the braking. Very scary behavior from a car. I'm considering buying and older car and restoring it rather than buying a new car at this point. (not just because of the rev hang, of course, personal data privacy is an issue too)

[@gweggorz]

Thanks for the lesson once again! This is a big problem in my '19 Mustang GT when I'm on track. Imagine trying to shift into 4th at 110 mph and having to wait for the revs to slowly creep down from red line :(

[@iamezza]

If your doing track days you should look at getting a tune to fix that

[@SenorBolsa]

Tunes usually change this behavior, or an experienced tuner can do it without much fuss if that's the only thing you want changed.

[@sergeysmelnik]

I had a 2015 mustang gt. Just get a tune, Id do e85 or flex tune if its in your area and simply ask to remove the rev hang. I think some tuners leave it in because some people like it like inexperienced drivers. It was always known the 1 to 2 shift always made the car jerk unless at red line so people just got the rev hang removed with the tunes.

[@MrSamdabeast]

I've been trying to get around my civic's rev hang for the past two years of ownership. I found smoothing off of the throttle instead of quickly releasing it helps a lot. Now it makes sense why that works because I'm just replicating what the electronic TB is trying to do in the first place.

[@the_irate_juan8462]

Now this is something I might give a try.

[@pliedtka]

Oh, I love my cable driven beater - shifts smoothly at 7k RPMs w/o problems

[@RWoody1995]

So by doing that you're not really getting around the rev hang, you're actually making the rev hang last even longer but because it's you holding the revs up not just the computer acting on your behalf you don't recognise it as a problem

[@MrSamdabeast]

@@RWoody1995 feels a hell of a lot better than waiting on the damn computer to do it. Just do it yourself. Or wait to shift until the TB is completely closed, but that's jerky and not smooth

[@veehexx]

FK2? Has DMF so convert to SMF and it'll fix. Not sure about fk8 as I think SMF.could still be flywheel weight as the cause

[@TobiasLeininger]

Regarding the explanation at the beginning at about 2:30: Many manufacturers have created linkages that translate the movement of the gas pedal into a somewhat linear opening of the throttle valve. For example look at the throttle body linkage in a BMW E30 325i with its little levers. No need for an electronic valve to achieve that. Sure it doesn't fully include RPM or airflow, but the feeling is great and controllable.

[@hphillips7425]

This explained why my timing was off shifting a Manual Transmission.

[@Ijusthopeitsquick]

To be fair, it's only one of several possible explanations :-)

[@rogrwi1co]

I compensate for rev hang by shifting as if I’m starting off from first gear at any gear change. Don’t step on the gas until you’re at the clutch bite point. Gone are the days where you have that see saw step of the clutch and gas pedal.

[@LorenzoManiglia]

@@rogrwi1co me too.. have been shifting like that ever since i got a car that hangs.. i'll have to say that it works, but surely impacts the clutch / mechanics wear.. Shifting lke i would do in any car that doesn't hang, would result in an undriveable experience.

[@markoos.bradley]

My '09 Ford fusion had some severe rev hang. I found the trick to driving an etb is letting up on the accelerator as you're beginning to reach your shift point (don't let up at the shift point), so your acceleration will decrease slightly, then shift and voilà it's smooth a silk. Takes some practice, but smooth shifts can be done if you're not wanting to gun it everytime you take off. 🕉️

[@gronki1]

same in my vw polo. need to push and release the gas pedal a split second earlier that i would normally.

[@valiant7802]

I drive a 06 Ford Fusion, I’ll have to try this on mine. Maybe it’ll help 🤷🏽‍♂️

[@aaronhorn6849]

The way i handle it is to half way float the up shift gear change. As you reach the shift point let off the throttle, as the gearbox unloads hold light presure on the gear lever and as it slips out of gear press the clutch and change into the new gear in one motion. Takes a little practice but very smooth and a little quicker.

[@bigtuco0496]

Went from a 93’ del sol to a 24’ Integra and I thought I just sucked at driving the Integra but this explains a lot more, thank you

[@RolandGustafsson]

My Ford Focus ST is pretty good in this regard but I have driven other modern manuals where it was very bad, a Honda Accord sport comes to mind. My Tesla on the other hand, can’t get it out of first gear so it just hangs all the time. 🤪

[@kc510]

My GTI isn’t bad but I had an 8th gen Civic Si and the rev hang was brutal.

[@DanielSanPedro]

Honda has killed the manual transmission because of this

[@finnickschnitzel7589]

That problem with the Tesla is easily fixed: Just load it up with high octane and thats it. Bam! Fixed.

[@newengland9thgen372]

K C You can get Hondata to fix the rev hang, a good friend of mine has a tastefully modded si that’s a real blast to drive. It’s so driver-focused

[@mikeb2496]

That's a great car drove one w 3 200lb dudes in it and it still got it done. Would recommend one, amazing brakes!

[@govindarajann7646]

Great video, Jason! Thanks to your videos, I enjoy driving my manual car even more, being aware of what exactly goes on inside the machine while I use my hands and feet. Great to know you enjoy manuals too. Pity they're going away so rapidly. The way you explain complex engineering concepts and devices is just amazing fun to watch and easy to follow. Keep it up! Cheers, Govind

[@BornofFire117]

I really enjoy your videos. As a car enthusiast, I feel it’s important for me to understand how cars and all their components work. Your videos make that easier for me!

[@johnberger5539]

On the race track the rev hang doesn't allow engine compression braking to slow the car and rotate it into a corner. You're left with having to use the brake to rotate the car so you lose one of the car control options available. BAD!!

[@daniellawson5127]

If left in gear the rev hang time is minimal I think and I'm pretty sure that it can be turned off with a tune... it's also a tradeoff minimized by the potential for computerized rev matching on downshifts. I always had a hard time blipping the throttle with my heel during mid turn down shifts.

[@wcsoblake85]

First thing I did when I got my Hondata is eliminate that rev hang. Drives much better now.

[@nateyoung6331]

What did you do to remove it?

[@wcsoblake85]

@@nateyoung6331 i have an 08 si. On one of the settings there is a selection of 1 2 3 4 5 6 which is associated with the gears. They have values in them already like 30 or 40. I changed all mine to 10ms and it eliminated the rev hang. I learned how by watching videos on KZbin. Just look up 8th gen civic hondata rev hang.

[@riley1733]

I disabled the rev hang in my 2020 Si Coupe with Hondata as well. Yeah, car drives a lot better now. Rev hang made it look like I had no idea how to drive the car. Drove me up the goddamn wall.

[@milkman3797]

My ‘17 Golf had heavy rev hang it really took the fun away from driving it. When it was cold it didnt hang much but once warm it hung like a noose. The explanation I got was for PCV pressure changes thus condensating oil, when it would hang then less oil condensates with the slow change of PCV pressure

[@AmateurPetrolHead]

@4:07 That's a SUPER CLEAN Engine Bay!

[@atharvathakre4821]

Has anyone noticed how clean the engine . I mean he wrote "super clean " 4:07.

[@sebastianalvarado2390]

Had to make sure I wasn’t the only one lol

[@Kana0211]

I'd rather have the throttle response of a mechanical throttlebody as I'd like to tap the petal to revmatch and not stomp on it

[@batmanlives6456]

I agree rev hang as described totally ruins the enjoyment of driving a manual transmission If I am in control of the car I WANT THE CONTROL!!!

[@whoknows1631]

Windbooster throttle controllers

[@chad6876]

True, this is one problem I have with a drive-by wire gas pedal

[@LeDank]

I got one of those aftermarket adjustable electronic throttle controllers. It’s pretty sick not gonna lie.

[@whoknows1631]

@@LeDank when you get it?

[@danielwlodawer1282]

Correction: You can make the curve "torque vs throttle" different with a mechanical throttle to. Maybe it's not commen to do that but it's easy to acomplish.

[@pliedtka]

It depends how signal from TPS is handled by computer 👍

[@Ijusthopeitsquick]

A throttle cam will only change the butterfly valve opening speed relative to the pedal input. That's not the same as having the valve position determined by the ECU.

[@danielwlodawer1282]

@behexen250 I mean the torque at the wheel.

[@kashi2000]

*wrx owners have entered the chat*

[@InternalAffairs244]

Clutch in, shift, count to 10, clutch out

[@jGRite]

*WRX owners wait for throttle response*

[@curtislovrak5390]

I was surprised at how much a cobb flash helped throttle mapping with my dads ‘16 wrx.

[@ktruong111]

Zack H I think my grandma would love your advice.

[@tezpokemonmaster]

not as bad on the Focus ST but I experience this as well, 1st to 2nd is either: shift, wait 1-2 seconds, clutch out. or shift, give the car 4k rpm, dump clutch, or it's not smooth.

[@CristianKlein]

Okay, so it wasn't just my feeling. :) I was used to driving a 2001 Peugeot 206. Once I rented a car and I found it significantly more difficult to manually shift gears without jerking. I just assumed "that's how newer cars are" and never gave it too much thought. Cool to hear the rationale behind it.

[@danh5150]

1) Yet another excellent presentation. I am an engineer myself and I always learn a ton of new things from your videos. Thank you, sir! 2) 11:38 Literally laughed out loud at the 'Super Clean' written in the dirt build-up. ;o)

[@CarreraJP7-GT]

"Super Clean" engine bay

[@MarcosSanchess]

Thank you very much for the video. I was studying to replace my 2011 Chevrolet Celta flywheel to a lighter one thinking it was heavy and causing the rev hang that were really annoying me because I was thinking I was changing gears so fast that I had to keep pressing the clutch until it dropped RPM to stop unmatched gear shifts.

[@2010ngojo]

My 2004 bmw rpm drops like a rock, no hangs. My 2019 hyundai hangs a little though.

[@huntermacdonald6431]

My 07 Audi hangs pretty bad

[@novinnovations4026]

09 Cobalt SS hangs real bad. And its direct injected.

[@philthomas7140]

I have a 2000 bmw and it has mechanical throttle body and it's beautiful

[@floridaheat305]

E46 doesn't have rev hang, thank God!

[@LeoinFrance]

You absolutely nailed it when you explain the advantages of electric throttle for the driver feeling part. Thank you so much!

[@dirtbikenrcman]

I noticed one of my Ford Econoline vans using OBD2 live data readers. When the engine would be at 100% load, the throttle body would go from line 52% open to 100% your explanation of the throttle body being sized for maximum load and a much higher engine RPM explains this. Thanks for helping me understanding this weird phenomina as ford engineers being cleaver in reducing their pumping losses.

[@paulstandaert2042]

Idle air control valves took care of that "lack of rev hang" thing back in the 1990s and early 2000's. Some utilized it more than others, but there was a solution to that issue.

[@catinthehat5140]

Rpm hang seems to have been eliminated on newer cars models

[@cheesemons]

Rev hang, a cancer in modern manual transmission cars.

[@corpsiecorpsie_the_original]

@Commander Spock - it allows manuals to still exist. Without it cars can't pass emissions

[@legnipok]

Can generally tune it out.

[@dieselgeezer18]

@@corpsiecorpsie_the_original yes it can. You just don't jam the throttle all the way in and you get better torque and fuel efficiency. I never press the gas all the way in when im on low revs. No need for electronic crap

[@Grooove_e]

@@corpsiecorpsie_the_original my 03 wrx without rev hang just passed its emissions a month ago lol

[@cheesemons]

I just let out the gas slightly earlier before pressing the clutch. It does the job but it's kinda hard to predict if the engine will rev hang longer or shorter. Kinda a hit and miss game sometimes.

[@mkshffr4936]

In the late seventies we had a similar problem with emission controls causing rev hang. In this case it was a dash pot on the carb to slow the throttle closing. The solution was to disconnect the the air pump, remove its drive belt, and remove the dash pot.

[@curtalford6126]

"Can remove driving jerk..." *shows himself driving*

[@dafff08]

this could explain why it sometimes seem like i cant shift gears smoothly..

[@NathanaelNaused]

This is likely the reason why

[@donaldtrump4540]

Not at all it’s because you don’t know how to drive Buy an automatic next time I can almost guarantee you sure as hell don’t know how to replace your clutch

[@fabianrudzewski9027]

@@donaldtrump4540 what does knowing how to replace a clutch have to do with being a smooth driver? There really are cars, that are hard AF to shift. The Opel Adam S is one of them. On the other hand, you can ride a Diesel Astra J as careless as you want, shifts will always go smoothly.

[@flybobbie1449]

@@fabianrudzewski9027 Some gear boxes are just crap. All the French cars i have owned had slick gear change, my BMW is notchy.

[@L39T]

fly bobbie my bmw is also jerky. especially 1st to 2nd.