Why Cars Backfire - Afterfire - Explained

Why do cars backfire? What is afterfire? Flames coming out your exhaust? Backfiring can be used to describe combustion occurring through the intake (traveling backwards) or through the exhaust, although this is also called afterfire. In this video we'll take a look at how an engine could have combustion travel out the exhaust.
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Backfire: • Why Do Cars Backfire?
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[@Tapport]

I love how your smile goes away as soon as you get to business. Your videos are so simply explained that I feel like I never go a video without learning something. Keep it up!

[@myleslouw1608]

dude is just there for the cash, he hates it there XD

[@andre1dre]

The anti lag system, changes the ignition timing that split second you let off of the gas. It ignites the fuel in the exhaust which forces the exhaust turbine on the turbo to maintain it's speed.

[@asjadsiddiqui7409]

So basically ignition timing is delayed when you release your foot off the gas pedal, so explosions are occurring in the exhaust pipe, and these explosions help boost power to the turbine of the turbo, and this way even when you let go of the gas you're still increasing power by letting the turbo take in more air?

[@ironduke6100]

@@asjadsiddiqui7409 almost completely correct; it won't increase power because the throttle plate is closed with your foot off the gas, but it prevents the turbo from slowing down, so after you put the pedal down again the turbo is still spinning at high rpm and you instantly have boost again without having to wait for it to spool up

[@asjadsiddiqui7409]

​@@ironduke6100 Ohhh thanks mate, that makes more sense.

[@TheDominik990]

I can't unsee lean af mixture... damn you internet :|

[@whomst7125]

Dominik B lmao

[@mazovkizta5488]

Dominik B thats what i just commented like seconds ago 👌

[@Forgan_Mreeman]

i cant tell if he's 19 or 30

[@EngineeringExplained]

Haukenslush Those are the only two options.

[@georgemaniat7224]

+Haukenslush He is 19 with the knowledge of 30.

[@sweeneysellsword2215]

+George Badass 30 men

[@georgemaniat7224]

+Todds Boot-E Well it doesn't matter how old he is, I've learned so much from him, thank you +Engineering Explained!!

[@yungpauly65]

He's both

[@everythingismediocre]

I've been around this stuff all my life and I definitely learned something. Excellent video. Astounding amount of content condensed to under four minutes. You're a born teacher.

[@EngineeringExplained]

I think the amount of thrust you'll see will be quite minimal haha. But on NHRA dragsters the exhaust produces a considerable amount of downforce (pipes are tilted up), something like 800 lbs or so I believe.

[@EngineeringExplained]

Thank you!

[@Marcel204_]

hi

[@delaticgaming2559]

Piskotek hey

[@mantis_toboggan_md]

@@Marcel204_ What's up?

[@ThomasVanHorn]

Adrian G. Oh hi mark

[@branchprediction9923]

@@mantis_toboggan_md Oh hi Mark

[@BradKlodowski]

That's designed to happen. Mini exhaust systems are designed to 'burble' which is just very minor afterfire occurring when you lift off the throttle. I think it sounds awesome personally.

[@jacobsquire8011]

Anyone else think he wrote "Rich as F**k" and "Lean as F**k" ?

[@moonlightastarixx3686]

I did too 😁😁😁

[@BeneficialQC]

I think he meant air/fuel

[@Astrix_Jaeger]

+Jacob Squire LOL

[@georgemaniat7224]

+Jacob Squire No I'm too much of a petrolhead so my first though was 'Air/Fuel' instead of 'As F*ck'

[@44R0Ndin]

+Jacob Squire Hmm. He may have MEANT air/fuel, but it does work either way. The condition is most pronounced with extremes of air-fuel mixture, so the air/fuel mixture being "rich af" or "lean af" is a quite accurate description. Fascinating.

[@dionyssismylonas3894]

This boy is always giving clear explanations. This means that he has understood well the material he presents. I often learn new things from him, or get the necessary confirmation of things I have thought - something always self assuring and comforting. Good job kid!

[@EngineeringExplained]

Thanks for watching!

[@EngineeringExplained]

Yes, this is overlapping of the valves. Of course, it is possible for some fuel to leak to the exhaust, assuming it is not a direct injection engine which waits to spray the fuel until the exhaust valve has closed.

[@EngineeringExplained]

1. From a stop, maybe not. You may have to burn the clutch a bit more. It's not going to ruin your car or anything, just might wear the clutch faster. I start in second frequently if I'm stopped on a downward slope. 2. Sure. 5th to 3rd is probably more common for me than 5th to 4th.

[@MugOfSolar]

You are so smart it's almost painful to watch. This stuff is so easy for you to understand you stumble over your words explaining it. Hahaha thank you so much for making this video.

[@snikwadRR]

Man, going back and watching this and looking at you now. You've come a long way bro. Great job.

[@LoveforJesusChrist77]

Omg you still do videos and explain everything the same way since 8 years before ,it's just perfect

[@edwardcornell1263]

FYI, all cars backfires. The reason why you won't hear this because of the well designed exhaust system on modern cars. Getting any car to backfire is very easy. Here is how you do it. If you want to hear it and feel it, then you may have to have the exhaust system modified to hear and feel the noise. Step 1. Drive the car normal until engine is warm. Step 2. Take car on the highway and give the car some gas, but then quickly take you foot off the gas petal, this will close the throttle body and keeping a rich mixture in the engine, because the engine will be lacking the proper air to fuel mixture. This creating the rich fuel mixture, if you wait a few seconds, and then put your foot back on the gas pedal, this will give the car more gas and oxygen to the existing gas that is already in the engine and therefor you will be burning a rich fuel mixture and a backfire may occur. The backfire will always occur the second the throttle body is re-opened. Engine backfire is most audible, on a car with a manual transmission, because of the fast acceleration as well as the constant opening and closing of the throttle body.

[@muhamadhafizazizan2493]

Edward Cornell is it normal? do we have to retune it using any piggyback? does it have any side effects especially on the exhaust valve?

[@edwardcornell1263]

Yes, this is normal. Not to be scared about. I think it is cool. I removed the first cat on my last car and my Car back fired, only by me doing what i posted above. Otherwise most of the time i was able to not have the car back fire. It is all about your driving. For tuning, your engine wants a balance of air and fuel, most cars are designed for a 14.7 mixture. Any difference in numbers than that, has the potential of engine damage. This is why alot of racers or ricers install wideband gauges in their cars, so they can monitor the air/fuel mix. If the numbers changes outside of their tuned range, then they should get that setup, rechecked. If your car is not tuned properly, than you might have more damage than just exchust valves. By removing the exchast system off your car, you will make your engine perform better, however by doing so may cause you to burn more gas. A exchast system puts alot of back pressure on the engine, this causing your horsepower to go down and your mpgs to go up.

[@darynnguyen9825]

I always thought it was due to my stock restricted piping. It's 2.25 piping, was thinking about changing it to bigger piping for more flow but I didn't want to lose the backfire.

[@edwardcornell1263]

U wont lose the backfire, bigger exchust pipes are better if you have room. My old car i had custom pipes, they ended starting from 1.6 inch and expanded up to 3.

[@irfaanmoolla]

I've recently changed my exhaust to a performance exhaust. Now I've noticed afterfiring when I shifting quickly during quick acceleration. So is it right to assume that everything's good and its just the new exhaust that's making the sound more audible (and the afterfire is visible at night to the car behind).

[@EngineeringExplained]

Thank you, spread the word my friend! :)

[@ravnulvthordnspyd]

You are awesome. I have a bad backfire on my 89 460 efi. Its rebuilt, so knowing this makes my life so much easier understanding how it works.

[@EngineeringExplained]

The internals of the engine would probably be fine with rich A/F; with lean, the engine can get a bit too hot since the burn is longer. But I don't think either are really too ideal.

[@panzerwaffen2873]

I know no everybody like every video in youtube but the reason why i subscribed to this channel is because how profesional and easy this dude explains everything how do some people can dislike this? Good job dude you are a talented one

[@macunion1225]

he looks like a smart justin bieber

[@EngineeringExplained]

The throttle closes, preventing air from coming in, but the injectors still inject a certain amount of fuel in the cylinders for a couple revs. This extra fuel doesn't have air to burn with, so it burns on it's way out the exhaust when it comes into contact with oxygen. My apologies, I was assuming you already knew do to some other comments you made on another video - though I may be mistaking you for someone else.

[@EngineeringExplained]

Yes.

[@TexasPoonTapa]

9 year old video. Damn time flies! God bless dude

[@bryankirk3567]

On motorcycles, the main cause of (internal) exhaust ignition is a badly seated (leaking) head to header seal. Fresh air gets drawn into that leak and any unburnt fuel mixes with that and causes a very lean air/fuel ratio which is ignited by the next exhaust stroke. This typically happens on over-run, on highly stressed engines.

[@EngineeringExplained]

The exhaust manifold gets hot from exhaust gas, hence, the exhaust gas is the heat source. If there is any fuel in the exhaust, and the temperature is hot enough, it can combust simply with the presence of oxygen.

[@bzster]

Interesting explanation on the back/after-fire in cars. I've heard a few high performance and race engines after-fire when starting. It usually happens just before the engine turns over, and the starter cranking sounds really slow. I always wondered what caused that, but now I'm guessing it's a combination of high compression and a rich mixture, but I could be wrong. Is this the case? I've seen a few videos of musclecars that do it and some race cars (NASCAR style?) that do it.

[@EngineeringExplained]

I would check the electrical system first for misfiring. Plugs, wires, etc.. Could very easily be a bad spark plug. I'm pretty inexperienced in auto-repair though.

[@jzsquad6866]

Haha sarcasm haha

[@charlesdowns1691]

my car had 2 spark plugs almost ready to spin out and 3 vacume leaks+i fixed those. i think a mechanic did it. ripped me off $300. my car is running good now. i avoid retarded mechanics in this area+rediculas!!!

[@codyi8714]

Ahh, the time machine of youtube recommended videos

[@oscarsoto7630]

rich af😂😂😂

[@boostfiend]

Awww, a child.

[@vincentbittel4860]

Jon Moore awww, nobody cares.

[@dylpepperino3746]

Awww ... damm

[@MastarCheef1337]

@@vincentbittel4860 Based "nobody cares" poster.

[@kleetus92]

Normally the afterfire occurs after a hard acceleration or period of high engine demand. On performance cars, there can be a lag in the reset of the AF mixture so it tends to be a bit rich. He covered what happens when a hot rich air mixture comes in contact with oxygen. There's a lot of factors involved to get that little crackle in the exhaust we all love.

[@andisadler2897]

eXACTLY RIGHT. tHIS HAPPENED TO ME. i WAS DOING 130MPH AND HEARD A THUD. Backfired.

[@emmanuelofori6521]

Very simple but clear illustration.

[@misters2837]

Jason, “Engineering Explained”… I have another explanation for the "Lean Mixture After-Fire", and though this is from real world wide band O2 data logging, while tuning on Motorcycles and ATVs (a 4-Stroke combustion engine is pretty universal): I have noticed that when the engine is up to operating temp, and tuned properly “for performance”, the engine especially when you roll off the throttle or close the throttle plates at higher than idle RPM, the mixture goes so far on the lean side of stoichiometric, that the spark plug doesn’t ignite it and when you have 2-3-4 “Cycles” that get dumped into the head-pipe it now has enough fuel (and oxygen because it didn’t get burnt/ignited in cylinder, PLUS many of these engines have secondary air injection systems) that it hits the hot carbon now ignites the fuel/air mixture sending out the well-known BANG-POP-CACKLE we are so familiar with, most commonly with low restriction exhaust systems. (DFCO “Deceleration Fuel Cut Off” on EFI equipped cars and some bikes is mostly for economy, as in the performance world, drivability trumps fuel economy, and almost eliminates this, they will however, sometimes “pop” in the DFCO transition period.)

[@EngineeringExplained]

The exhaust gas temp is hot enough to combust gasoline vapor, if oxygen is present.

[@holden3083]

👍. Well done on your channel. It has grown a lot over the years.

[@Eliasccv14]

Oh my gosh a video from 8 years ago! This is pretty cool to see actually 😁

[@I2YANx]

You deserve more views, great clear explanation.

[@TheRaysteve]

can't stop watching ur vids. im addicted. good work

[@EngineeringExplained]

TheRaysteve Happy to hear it!

[@harryclark3388]

i'm 13 and i'm into cars and how they work and i saw one of your videos and they are really cool im learning so much from this thanks keep up the good work

[@mingyinwilsonchoo7033]

Very clear explanation! But there is one thing that keeps puzzling me. On the newer models of Porsches (9x1 onwards) with 'sport exhaust' fitted, the sound they produced are mesmerizing. They sound just like after-fire (banging and cracking noise). May i ask how are these sound produced given the fact that backfiring may not be the answer to these new cars with modern combustion technology. Thanks. I am a big fan of your channel btw :)

[@ashman0071]

on the turbo 3.0 liters it's programmed into the engine management system as a 'Turbo Anti-lag' feature. Some continued ignition in the exhaust system helps to keep the turbo's Turbine Impeller, which is situated in the engine's exhaust stream, spinning faster. This way, when you reopen the the throttle the turbo is spinning at a much higher rpm and ready to drive the Turbo's Compressor or Intake Turbine more effectively.

[@The_R-n-I_Guy]

I had a vacuum hose come loose in an 89 Eagle Premier. When I tried to shut off the engine, it backfired so violently that it blew my muffler apart. The back of the muffler blew off and the case split open at the weld. Scared the crap out of me and everyone else at the gas station. I had taken off the plastic engine cover while I was working on something and I didn't realize that the engine cover was the only thing holding the worn out vacuum lines in place. Once I reattached the lines and put the cover back on, I never had another problem. Except for the extremely loud exhaust of course

[@lahnie95]

you should be a teacher... I've watched multiple videos of yours and I learn more from you than I do from my automotive teacher... What am I paying him for!!! KEEP UP THE GOOD WORK!!!

[@The_R-n-I_Guy]

I don't know everything. But I know enough to get by. I love learning something new.

[@matisstar]

dammn this guy used to be such a geek, look at him now driving sports cars and everything

[@shellracer3189]

I love your videos man keep the amazing work i hope to become a mechanical engineer or mechanic one day

[@tristanyseult]

a lean mixture burns faster, hence pinking. a rich mixture burns slower as it has more molecules to get through so slowing the flame rate down.

[@chrispowerz]

No! Sorry, a lean air fuel mixture burns FASTER than a rich mixture. The richer mixture burns further into the power stroke and is why it makes more power. I love your videos and your almost always right. Had to point that one out. I went to school for this stuff, im sure you did too, but im certain lean burns faster. Example : pooled gasoline vs gasoline mist. The mist will burn faster.

[@petert2922]

Lean mixture burns more slowly? Lean mixture burns fast, all the way to being so fast that becomes explosive. Afterfire can occur for a several reasons and are cool. Backfire means preignition which is destructive for the engine, it will trigger a check engine light if the knock sensors pick it up.

[@joelschmitt8490]

yes part 1 of your argument is right of possible lean fuel with vaccum leaks to a certain point but it does not burn slower. it burns hotter. go to a race track and look at the exhaust. cars that have black exhaust or unburnt fuel is rich and they don't win. find the exhaust with a gray tint or no exhaust residue at all. lean is fast and fast it hot

[@KropfkraenklerNo1]

maybe you could make a video about where deceleration pops come from? my 2012 camaro SS does this a lot, and there are lots of different opinions of where that actually comes from and what happens in the exhaust.

[@EngineeringExplained]

Likely, yes.

[@willk3807]

3.15 million subscribers congrats. Just so you know thou I was subscribed and noticed KZbin did the unsubscribed thing.

[@TheFlacker99]

Left ya a like, my buddy's blazer loves to do this when he gets off the highway and turns off his truck.

[@GibsonLesStrat]

Basically when you hear "burn" the clutch, that means that you are wearing the grooves on the clutch out. This can happen if you don't rev match your downshifts or if you start in like 2nd or 3rd. Won't hurt the car, but the clutch won't last as long when you drive like that.

[@MY_USER_WAS_TAKEN]

been watching a few of your videos now, good stuff keept it up !

[@OnDUBzProductions]

love your videos, very clear, very descriptive and professional KEEP IT UP MAN!!!!!!

[@rishirammoonesar3171]

He knows his stuff my college teacher showed me his video during classes for explanations just like this video.

[@oswaldoflores9206]

I love how this got recommended in my feed.

[@EngineeringExplained]

Well not really, unless they have ignition delay for an anti-lag system. Otherwise it would be pointless to delay ignition. They backfire from rich a/f mixture and possibly the lack of a catalytic converter.

[@EngineeringExplained]

I have plenty to learn; what I have learned I've learned mostly on my own. I'm a graduated mechanical engineer; you can read more about me on my website (see description) on the about me page.

[@dpro1995]

Hi, Just a question : why do V8 supercars often have afterfire when decelerating? I know you explained it in your video, but competition cars are prefectly tuned and they don't have mixture or valve troubles... competitions cars' engines are not left to any coincidence. So why do they have such a huge flame during deceleration?

[@anythingrc4715]

They could use a turbo anti lag system?? Also 9 years later you finally get a reply lol

[@slybunda]

he is the definition of paper mechanic.

[@dannywitt6483]

*engineer

[@chungocquang]

Can you please explain the Anti-lag system on turbo cars? Thanks. Great videos

[@EngineeringExplained]

Quang Chu I have two videos on it, have a quick search on my channel. :)

[@ashman0071]

Although you think that the engine isn't getting any fuel or air when you completely take your foot of the accelerator, the engine management software still adds some fuel, and leaves open the throttle body a little bit even though you think the throttle was closed completely. Then the engine management system also retards (slows in time) the ignition so it occurs in such a way that ignition hasn't been fully completed before the exhaust valve is opened (more or less). This way on a closed throttle there is some amount of unburnt air/fuel mixture that ignites within the exhaust manifold to help keep the Turbo's Exhaust Impeller Spinning at a higher RPM - hence less lag when you go back onto the throttle - pretty slick, right ?

[@3-E]

You can get any car to after fire if you can program the ECU to cut spark at redline instead of cutting fuel. Air/Fuel accumulates in the exhaust system when ever you bounce off the revlimiter and it shoots little fireballs. It's certainly not good for the health of your exhaust system but it sure is fun to watch

[@corydiesel88]

Awesome videos man! Also, excessive valve overlap could cause afterfiring too right?

[@dtekie18]

As usual explained perfectly concise.

[@sinatabrizi4794]

thanks for all the videos i've learned lots from you. keep em coming

[@EngineeringExplained]

The flame itself may not do much, but it's not too great to send a lot of fuel through the cat, or burning fuel for that matter.

[@davidcrandon2329]

Your vids are great. You are a very good teacher. Now, suppose I actually wanted a little aftercare on off- throttle deceleration. The loud gurgling and burbling sound. What would be the best way to tune the aftermarket ECU to achieve this? I just think it sounds cool! I had a S2000 that did this, but I don't know how it was tuned to achieve it. I'm building another one, this one supercharged, so what would you suggest? (Interestingly, some manufactures are building this into their street cars such as the Fiat 500 Arbath).

[@alessandropru]

so young (compared to today), but just as informative

[@RubinH]

2013! Can't believe the difference to today.

[@charlessmith263]

I heard deceleration backfires before in internal combustion engines. Here is my thinking.... Gasoline has a flash point before it explodes as a backfire/afterfire event. When the backfire happens, you see the flame coming out, but if you hear the bang or pop without the flame, it is possible that that vehicle had a BFA - a backfire flame arrestor, so you hear the explosion but not see the backfire flame. Here is a typical situation often seen in illegal street racing.....which makes up usually over 50 percent of vehicle backfire events - - - 1. A driver fully floors the car, causing the gasoline in the exhaust to reach close to the flash point temperature as it heats up. 2. Then as the driver decelerates, the gasoline's flash point temperature is breached and goes up in spurts---and the gasoline explodes (I assume at that point, more oxygen goes into the gasoline as an oxidizer and fuel, and much more heat is produced, causing the explosion), resulting in the pop or bang out of the exhaust pipe. The flash point temperature then eventually goes down after you hear the backfire or backfires go off--at that point, the gasoline temperature goes down as well as the oxygen levels, reducing the chance of further backfire explosions. Then there are the idling backfires. My guess is that in this case, the flash point of gas has been reached at idle by some fuel mixture that is right enough to cause the gas to be so volatile that the flash point temp is already reached and spikes and goes down in temperature, causing the pops and bangs even without decelerating or revving up.

[@LeaveYouOnRead]

2 questions: 1, is it good for the clutch to start on second gear? 2, is it ok to skip gears when downshift? Thanks!

[@tophatpigeon2491]

So uhh only 8 years late but here's your answer: 1. It depends on the scenario, if you are on a level road it will cause some wear to the clutch because it will be slipping since the engine speed is not as fast as the gearbox wants. If you are on a road that is slanted downhill the car already will have an easier time getting momentum so it is not so bad and it won't slip as much. 2. As long as you are holding down the clutch and you are in the right rpm's and speed you can shift from any gear to any gear. Say you are in 5th gear and you have braked to about 10 mph while holding the clutch you can put it into second. You do not have to go 5-4-3-2.

[@NorthernSkiAndCycle]

Should make a video on rotaries. I personally own an RX7 and know how they work, but would make for a nice video for those who don't.

[@EyebrowsMahoney]

It's either due to fuel accumulation in the exhaust due to a rich a/f ratio. When they cut throttle the mixture becomes stoich and the hot pipes/cats ignite the A/F mixture. A lot of decel after fire comes from a instant leaning of the exhaust due to high flow... (what most super cars and modded cars have) and the hyper lean condition in the exhaust causes the combustion. No damage is done, it's just mildly annoying to some, but lots of fun for the rest.

[@buismlawina]

Cool vid, now I get why the Evo 3 in initial D was backfiring, they were using a delayed ignition system.

[@tomcresswell3587]

Backfires are not exceptionally loud. They make a big "THUMP" or "POP" but that's about it. Sort of like a great big party balloon popping in the next room. Afterfiring is when fuel and air get through the cylinders and explode in the exhaust system with a very loud BANG like a shotgun firing. "POW!" Many people mistakenly call this a "backfire" but it is really an AFTERFIRE. Backfiring is through the intake. Afterfiring is out the exhaust. Backfiring is more dangerous than afterfiring because a backfire can set fire to any stray fuel in the carburetor or induction system. Afterfiring might damage a muffler but little else even though it makes a lot more noise. Afterfiring can be caused by a number of problems. Intake or exhaust manifold leaks drawing air in when the throttle is closed can cause popping and banging in the exhaust during deceleration. This can also happen normally on aircraft with very short exhaust stacks. Listen to a P-51 Mustang landing and you'll hear what I'm talking about. The stacks are so short they draw air back in when the throttle is closed. Loss of ignition on one cylinder can result in that cylinder's unburned charge being expelled into the exhaust manifold where it can be ignited by the other cylinders and this makes a big bang. Incorrectly connected spark plug cabling can do this, too.

[@000Trauma]

Damn boi that mixture rich AF!

[@FreakishPower]

After seeing a bunch of your more modern videos, this was a shock to see - a 7 year old video that looks like it was made in 1980. Maybe do a video on how scissors and electric razors work?? hahhah

[@bestmastermind951]

very imformative yet not boring video! short and to the point u should be a teacher at UTI or something

[@EngineeringExplained]

Hmm, perhaps if the mixture changed quick enough, but I don't know if it would.

[@EngineeringExplained]

I should have an N2O video in a few weeks!

[@xheikharslan1275]

Hello ...bro i need your help....em from pakistan ...em modified d16 single v tect engine ..how i do my engine make bake fire every knocking ...plz help

[@benjayfernandez9220]

Please explain how a valve bounce or valve float occur. Got experienced it myself but I don't understand since I'm all pure stock.

[@Papa7Bravo]

Normally pretty simple, you're over revving your valve springs to the point they dont close fully by the time the came rotates back round to open it again, and bounce is a spring I believe too soft which cant keep it shut so when it does close the force of it closing causes it to 'bounce' open again.

[@connivingkhajiit]

@@Papa7Bravo Newton's first law!

[@rx8cosmo]

im a big car enthusiast since i was kid and i love your videos man!keep it up!one question though: so supercars e.g. Lamborghini aventador that we see in videos afterfiring whats the reason behind that?are they runninh rich f/a mix??

[@EngineeringExplained]

Perhaps, yes, if the fuel were to escape through the exhaust.

[@EngineeringExplained]

Well if you have cats (which you probably do) the fuel going through will ruin them over time. It's best to have a proper air/fuel ratio.

[@bimmerlife5452]

Haha my e39 530i spits fire cold intake full exhaust stage one dinan tune I love it pulls hard

[@000Trauma]

This was a neat video I found out what i was looking for, nice job!

[@JHAV86]

A video on N2O systems would be pretty cool. I'm sure they're simple but some of the vocabulary and measurements would be nice to know

[@azndragonx2]

afterfire(fire on the exhaust system) = rich mixture. backfire(back fire into the induction system) = lean mixture. u need to get those to term right

[@KaCaNgGuru]

few mods i have done is. Exhaust Cat-delete Exhaust Center Pipe Straight [no resonator] Exhaust Muffler J's Racing 50rr Hondata Flash Pro..

[@TheSuprasalas]

you can also have back fire by have no exhaust(straight pipe) or having a leak in your exhaust system. Also if your secondary air pump staying on for a long period, it can create a back fire.

[@Xgamer121X]

Engineering Explained, I have a question I have wondered for years now. I know many cars and more commonly motorcycles, use secondary air injection to reduce exhaust emissions witch can cause popping on deceleration. But, on fuel injected engines, wouldn't deceleration fuel cutoff (DFCO) prevent ANY unburned fuel from being in the exhaust in the first place? My 1999 mustang v6 automatic always lightly popped out the exhaust when decelerating, how is this happening if the fuel is supposed to be cut off on deceleration?

[@charlesdowns1691]

not sure but my glass packs do that popping on deaccel also. +i will find out and answer this question since my son would know

[@bruderrudiger9574]

@@charlesdowns1691 and?

[@TarenGarond]

The real reason of "popping" in the exhaust in lean engines is missfires that later is ignited by heat from the exhaust valve, manifold or from the exhaust from another more successfull ignition!

[@carlosduardo2836]

Hey dude, your videos are great and really usefull, i'm not sure that you are in to, but it'll be awesome if you make a video about carburetor picking!!.

[@Amm17ar]

You should explain which of these problems/situations are ok to have and what scenarios are good and or bad.

[@EngineeringExplained]

+Ammar Hafeez well, there's really no form of 'good' backfiring. Ideally all combustion occurs within the cylinder, not before or after entering/exiting the cylinder.

[@Amm17ar]

Oh cool, thanks a lot man! Lol I was just wondering because you see so many videos of Lambos and other high-performance cars after-firing or backfiring.

[@josezapata7596]

Thanks for explaining man 🤠

[@etherealvox2010]

Your videos are awesome . Keep up the good work !

[@hoenderhoender]

Nice explaining thank you very much. I now know why my bike spits fire:)

[@craik7]

Is ignition Delay related to the starter / coil ? i.e. of coil is very old not functioning properly etc ? thanks for sharing this valuable info