The ULTIMATE GUIDE to Idle Tuning! (For ECU Upgrades & Engine Swaps)

This video can apply to all sorts of cars so share it with your friend who's got a sick swap that won't idle right! See below for more notes about this video.
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Extra Video Notes:
0) Yes, step zero. MAKE SURE you don't have any vacuum leaks before tuning idle.
1) PID values in the idle settings could have a video of their own, the coverage was very brief here. See tuning manuals for more information.
2) An alternative to unplugging the ISCV valve during idle screw setting is to lower idle to 0% duty in the tuning software.
3) In the MEITE idle settings there's something called "PID Deadband" that can be very useful. If you're using closed loop, and have issue with idle hunting but only by 50-100RPM, try increasing the Deadband to a larger value. This is the amount of error (Target RPM vs Actual RPM) that's allowed by the ECU where it will not attempt to chase the target. So if your target is 850RPM, and your engine is idling at 900RPM, with a Deadband setting of 50RPM, it will not attempt to chase it down to 850.
4) Pertaining to AFR affecting idle: A very common upgrade is larger fuel injectors for boosted applications. The stock ECU can handle about 15% larger injectors, which is around 300cc or maybe slightly larger. Above that (RX7, RX8 injectors or bigger) you need a standalone. But when you upgrade injectors on a standalone you need to input the correct settings for those injectors, rather than just subtracting fuel from the maps and tables. The 2 main settings are injector size and dead time. Dead time should be provided when you buy aftermarket injectors like Injector Dynamics, Deatchwerks, etc. For OE injectors like RX8 you can calculate it (www.miataturbo.net/ecus-tunin...) or if you need to guess you can just use a value like 1.00 and it should be close enough. It's best to get it accurate. Keep in mind your entire fuel tune will be thrown off when you change dead time. (In MEITE: Go to the search box and type "dead time". In Tuner Studio: Fuel Settings - Injector Dead Time). You also need to change the injector size which will also throw off the entire tune, so do that as soon as you install the injectors. (In MEITE: Under "START" Menu in the Injection Driver box, adjust "Pri. Inj Size". In Tuner Studio: Basic/Load Settings - Click "Calculate Required Fuel" and input your data, this will repopulate the Required Fuel value. Double injector size = half the required fuel value.)
5) If you have a 1990-1993 (1.6L) Federal car, or 1990-1992 California car, it runs what's called batch fuel injection. This is where #1/3 and #2/4 fuel injectors fire simultaneously. You may notice, especially with larger injectors, that idle AFR needs to be in the 13's to be stable, this is normal. Alternatively, you can add 2 wires between your fuel rail and ECU to set up sequential injection. You need 1 signal wire per injector to do this (Early cars had 1 signal per 2 injectors.)
6) There is a lot that goes into this simple seeming topic. It can be harder even than cruise tuning or WOT tuning at times. If you guys have any pro tips you've learned from experience, drop them in the comments!
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Additional Info:
ME221/442 Tuning Manual: motorsport-electronics.co.uk/...
ME221/442 Base Maps: motorsport-electronics.co.uk/...
Megasquirt Tuning Manuals: www.msextra.com/manuals/
MS2 Base Maps: www.megasquirtpnp.com/mspnp2_m...
MS3 Base Maps: www.megasquirtpnp.com/mspnpp_m...
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0:00 Intro
0:51 Idle Components
6:27 Base Idle Setting (Stock & Standalone)
10:43 Open vs. Closed Loop Modes
16:30 What Variables Can Affect Idle?
18:59 What If The Car Won't Idle At All?
23:29 Idle Dipping / Stalling
26:26 Spark Scatter / Idle Advance
31:13 Pro Tip & Additional Idle Settings
34:29 Setting Up A/C & Fans
39:18 Outro

[@1knowsnothing1]

A few tips: 1) Before you adjust the idle set screw mark your screwdriver with a marker and count the number of turns to fully close. Then write it down. That way you can always return it to stock 2) In Closed Loop Idle: Bracket your spark map in the idle area. That means set your low rpm to like 700, 900, 1250. I set mine to 14 degrees in the 700 & 900 and then advance it in the 1250 area to a point that keeps it from hunting/surge/ above this area. This will be used in conjunction with other functions below. 3) In closed loop idle set your Idle Cranking Duty/Steps to a Duty % high enough that you don’t need to depress the throttle pedal. 4) In Closed Loop Idle “Closed Loop Initial Values”. I bracket my setting like above starting at 700 rpm. Because I want my car to idle at 850 rpm, if it’s ever below 850 when it first goes into CLI it will ramp up to 850 by adding a higher Duty % at 700. Then as rpm increases on the scale drop the Duty % . This also seems to help steady it. My target rpm values are 700, 850, 950, 1100, 1200. I set the highest value of your IACV’s duty % in the 700 rpm field and taper it off the higher you go in the rpm scale. 5) Play with PWM Idle Voltage Compensation. I set my charging voltage, which is like 13.5 to 0.0 PWM. I put these numbers in the middle of the range. To the left on the scale, the voltage drops (due to load) all the way to 11.0 volts. As load increases the voltage drops and so want to add Duty % to the IAC to compensate. I use 2 % at 11 amps and -3.1 at 14.5 amps. This brackets your idle based off things like the load from lights, radio, AC etc. 6) Idle Load Advance. This can advance timing when load increases similar to above. At low load below 30% I have my advance set to 0. At the highest load setting of 70 my advance is set to 4 degrees. 0-4 degrees from 30-70 Load% 7) PID settings are not that helpful in MS2 but P & I are less effective than the D settings in my experience. I set my Gain to 3200 my P to 20.0, I to 60.0, and D to 200. I don’t have PS or AC but I’m putting it back in. My idle is rock solid in CL at 850 rpm. Good luck everyone!

[@TheCarPassionChannel]

And this is why I love the Miata community. Thanks for taking the time!

[@1knowsnothing1]

We wouldn’t be here if it wasn’t for you Greg! Thanks for everything you do.

[@GuernB2]

I took a screen shot of this for when I get a MS for my Nb. Thanks!

[@mitchgoldfarb5730]

Iv been waiting 2 years for this video… my prayers have been answered. Thank you

[@street_fighter_mx5]

Me too

[@SpeedWhomp420]

I literally just got my car with a new MS to crank over yesterday and was about to start watching idle tuning videos. Holy good timing Batman!

[@TheNightOwl082]

I'm just about to throw my bp5a engine in my 94! Best Miata Dad ever!

[@sugoi4983]

please do acceleration enrichment tuning, its another huge deal with having an actual dailyable setup

[@grahamnelson5376]

Glad to see daddy Greg calling out all the jabronis dropping into neutral at the end of every pull

[@TheCarPassionChannel]

Catch me yelling at my screen watching people do it in videos

[@gm5383]

Imma call it now, pretty sure this is going to become one of Gregs most watched videos

[@FDB77]

Greg: “Oh wow you actually clicked on this video” Me: “What? You didn’t expect me to watch a new CarPassion video??

[@sn302802]

Dude, my name is Zach and that part where you said to pay attention really freaked me out lol. I'm too stoned for this. I should also mention I have a 1.6 and i have some idle issues

[@str8slayn1]

We need more Zach's with Miatas

[@TheCarPassionChannel]

MiataZach1.6 is the real Zach from the video, sorry lolllll

[@CashedOutCars]

Less exciting than big boost but very helpful!

[@evannoriega-thomas371]

This is a video that so many people, including myself, needed. I switched to a standalone a couple months ago and even though my car doesn't run now, I am super excited to get it running so I can fine-tune some of these settings myself instead of going back and forth with my tuner.

[@jessegraas7168]

Thank you so much Greg! I've been wanting to learn idle tuning for so long but haven't been able to find a reputable source of knowledge to do so and I really don't have the time to hunt for information. Keep up the good work! It's much appreciated.

[@EndriuGolara247]

I don't have a miata, neither project car, but I probably will watch entire video because you always mention many interesting things

[@andrewbutcher4343]

I have a ME211, got the tuner to work his magic and never touched it scared of messing it up this gives me way more confidence to play around with it. Cheers greg

[@FredBicho]

One of the most important videos on KZbin about idle. So much information. I love your videos bro. Thank you 🙏

[@0JThomps0]

The algorithm finally blessed me with your channel last night and I've been binging your videos ever since. Mad props on the information you provide. I'm currently building a 08 STI hatchback with a Precision 6466.

[@miokujou]

Getting this channel recommended to me is one of the best things YT ever did! Thanks YT! I love vids like this that goes in depth with the explanation plus actually showing what will happen if do this and that. Cars now a days are an engineering marvel with more than a century of R&D put into them. Being able to explain these kind of things in a way that ordinary people like me can understand shows how good of a teacher you are. Great Job!

[@t32prod.98]

i watch these videos when i work on my own miata. you’re a god send. thank you for everything you do for this community.

[@tylermfdurden]

I set my base RPM (with the idle screw) to the same as regular idle rather than ~100 below. That way I don't get random RPM dips when coming to a stop or turning on the A/C

[@warrendegonzague]

Thank you! You may not remember but I DM'd you about these things and you really set me in the right direction. Now, a video... nd you explain stuff really good. Thanks again big bro

[@Chakotay33.]

This is incredibly helpful. I bought a '94 Miata a couple months ago and installed a Megasquirt to lean it out a bit (was running too rich), and I struggled for so long to get a stable idle. This video is a godsend. I literally have run into a few issues he speaks about and this is awesome to understand how to fix it. Greg is an awesome guy.

[@street_fighter_mx5]

Bro I wasn’t a fan of your page that much but you finally became my Miata Hero!!! Seriously what a a great video for the ME442 guys!!!

[@mattt4706]

I literally just installed my Megasquirt like 2 weeks ago and you post the Holy grail!

[@OGPedXing]

Good tips, keep in mind if adding throttle keeps it running, you might have too much fuel rather than too little air. 👍

[@TheCarPassionChannel]

Yes - which is much easier to figure out once the engine is actually running and you can get an AFR reading :)

[@matthewdrake1434]

FINALLLY OHHHHHHH MY GOD YOU ARE AMAZING CRAIG! Seriously so thankful to be a part of the miata community!

[@niklaslyssi5749]

Bro this video came out with perfect timing. I build me an overhauled motorblock for tuboing my 89 NA and am running into severe Problems. You are helping a lot bro. greets from Germany

[@mannys18s]

Like always THANKS MAN!! Been learning close loop tuning, and found something confusing. The way you explain it.. finally clicked in my head.

[@SuperNarion123]

I just got my car idling a few days ago on open loop but his video gives me way more knowledge !

[@s.willis8426]

I've been watching your vids for a while but this boring technical lame ass idle tuning video has truly given me the confidence to swap out my ECU next spring when the Miata comes out of storage from a (hopefully not too snowy and cold) New England winter and I can't thank you enough for making it. Seriously, a true inspiration, thank you. Keep doin' whatcha' doin' dude.

[@loafdad]

Learned something new !!! you gotta be kidding that was a proper schooling. Thanks so much. Amazing video.

[@tylerreed7385]

Super glad this vid came out, Littlraly wanted to learn this but wanted more mx specific

[@yakhunt9424]

Superb video, and nice to see the ME442 in more detail. Cheers

[@TeddyD802]

Engine idle is critical ! Thanks for doing this, I’m about to install MS on my 94

[@smalltom3373]

spent a day or so on forums trying to find decent information as to how to setup idle, nothing. but 1 cpc video later and im pretty certain my car may idle well-ish tomorrow. unfortunately unlike your basemap mine was pretty pathetic and didnt do much for my car so i have pretty much had to figure out alot on my own and im sure your videos are going to help alot

[@mazboengineer]

Brilliantly informative (as usual) 👌🏼🤓 Many thanks Greg 🤜🏼🤛🏼

[@liorlevi3991]

I must take a few minutes to write this comment. First of all, the video quality is of a high standard. The explanations you give can also be understood by people who do not really understand the subject. Secondly, you mentioned that the original ecu should be respected for all the little details that are controlled by it. And when I think about it it's crazy. There are so many things that need to happen and it is not so simple that it just works in every possible condition. It just makes me think how hard it is to calibrate a computer to an automatic transmission ... and one last thing is to thank you for sharing your extensive knowledge with us. I really appreciate it.

[@fencoflex5089]

bro... you might've saved my life... you make it look so easy and you do a great job on explaining. thanks dad 😅

[@Everydayprojects365]

My car idles perfectly at 10:1 and 12:1 lol but that’s because I raised my idle speed and increased my iac valve duty cycle,this is a great video

[@maxp8892]

Great job of explaining what all is involved. Thank you.

[@Viper70225]

Finally Meite tuning, coool! Thank you Greg!

[@repbegger766]

Thank you so much I had a me442 laying around for a year now never could get it to run right at all ended up going back to oem ecu. hope there will be more vids on how to set this up.

[@ahmadsaadi984]

Great!... I really got a lot of useful information of your video. Thanks MAN!

[@Ooo_dang_jesus]

Super informative video! Thank you for this one

[@umoview]

Awesome content mate! Very informative and useful

[@Lecherous_Rex]

With the stand alone you become the engineer. Someone programed the stock ecu to work with all factory motors with all their manufacturing variances. The setup is daunting, but you can accommodate mods and personalize on another level. I've been researching what can be done with the stock ecu after hearing about Cali wanting to test the ecu at inspection stations. Massachusetts is always a few steps behind but usually follows suit.

[@chickells3192]

Baller video dude, thanks. Only needed to raise my base idle on stock ecu on my 2000 NB. When I shorted the TEN to GRD with a paper clip it killed the engine, so that was weird. But the screwdriver lowering the idle fixed my rough idle.

[@street_fighter_mx5]

I am Loving this video so much! Man!!!!

[@ljamison912]

Dope explanation of everything!

[@HooverTuber]

I’m just excited to be here

[@richcracknell]

One of your best, Thank you! I have an NB engine in an NA, ME442 and idle dip issues only when hot. Bay area tuners maxed out for months, this gives me some options to take a look myself. Immaculate timing!

[@yakhunt9424]

Turboed NA here with an ME442. Was getting issues with idle dip as well as stalling on hot starts if the car had been sitting for 10 -15 mins. Not sure what your set up is, but I found that my GM IAT was getting heat soaked and making the ECU run lean. Log your intake temps and see what you find.

[@richcracknell]

@@yakhunt9424 A thousand thank yous! This fits the symptoms perfectly, will look to relocate the sensor before messing up my tune trying to sort a mechanical issue

[@yakhunt9424]

@@richcracknell I've moved mine from the intercooler pipe inside the engine bay to just after the IC outside the engine bay. It's better but it's still not perfect. The GM IAT sensor has a slow response time (10sec) and I still have to crack the throttle throttle a little to stop it bogging down after a hot start until it adjusts to the real temps. It's a work in progress. Good luck

[@G.J.G.P.]

24:00 thats been done, because thats the method to calculate the drag of the drivetrain to then calculate engine power.

[@street_fighter_mx5]

Best KZbin ME442 video to date

[@shirtz69r]

Thanks Greg. The video I didn't know I need.

[@glenjamindle]

I think you should mention to make you there are ZERO vacuum leaks before tuning idle. I struggled with my idle and turns out my IAT was loose af and I didn't need to tinker in the MS

[@TheCarPassionChannel]

Adding this to the video notes later

[@madspikes205]

Great video, very useful content

[@deathbyglamour4268]

THANK YOU THIS IS THE PERFECT VIDEO

[@miata9916]

Great video. Loved every second of it, and learned so much. The meite software is really messy sometimes, so I really apprechiate the explanations for the idle tuning settings. But I have to say, that I would have loved if you would go a little bit further into PID closed loop tuning. I know its kind of a go-by experience and feeling kind of tuning, but either way. Loved the input!

[@yakhunt9424]

ME442 here and you're right, it can be really daunting

[@EdA-bz3bu]

Excellent bud. Keep it up.

[@laszlototh5956]

Oh, the good habbit of red line clutching mentioned. I did a 250 4 cyl street bike that did not idle. I set the idle mixture and speed great it was a pleasure to hear the bike purring on idle. My test ride was a treat. I gave it back to the happy costumer and he came back from the test lap and complained the bike dies when he clutches after a pull (it red lines above 10k). He asked me to raise a silly high idle to compensate. I could not understand him...

[@TheCarPassionChannel]

That's especially sketchy on a bike, have fun getting wheel lock if you make a mistake

[@38tech]

Crazy informative! Thanks a bunch.

[@honzaskvaril2259]

Awesome man! Thanks so much. 👍

[@knoxsp]

Brilliant video.

[@JohnDoe-je3cr]

hi Peg Greeters, thanks for the video!

[@luismoreno602]

Dude I didn't even know what was a miata until your channel lol now I own one

[@Dawnhun1er]

Great video, as always. Love your content! Can you do anther one on hot restarts and heat soak? Cheers from Germany! 🇩🇪

[@jp2246]

Love this channel!

[@Shiznit304]

Great video miata-dad! My miata idles perfectly with A/C on or off with my SpeedyEFI Speeduino in open loop.

[@WigglingWaffles]

some things I've learned over my 5+ years of self-taught tuning on megasquirt: -keep your VE and spark tables relative to whatever idle controls like when entering/exiting idle. if idle control consistently advances to, persay 20 degrees at 1300 rpm, make sure your spark table reflects that or something close. otherwise you can end up causing the idle to hunt right when it enters closed loop because it has to reference a number that isn't close to what is stable at that RPM. It will cause jerkiness and you will actually feel the car enter idle. This is bad. -learn to tune PID. seriously, learn to tune PID. It will change the ball game as far as idle stability, at least after you discover how to control it with ign advance and it will serve to open up understanding for other features - EGO and boost control are good highlights -stalling - dont lie, that lightweight flywheel and your tune don't agree and you're thinking it's too savage for you. you can tune out stalls...sorta. you can at least make it harder to. See next point. Finally - DATALOG and learn to read logs!!! If you are having consistent issues that you cannot identify, look at the data. What's your idle valve doing? What's ign advance like? Is the engine entering and leaving idle? Why is the idle valve making such huge % steps? What is Graig's real name? It's all in the logs - they are your greatest tool and making adjustments based off those readings will yield better results than random shots in the dark.

[@duske00]

Nice video!, my IAC is just blocked off with a hose end. with idle control off. If u set the idle timing at 1k rpm at ~7deg and 800rpm&1300rpm on 13 it will fall and stay in the 1000/1100 rpm range :) Less parts to break i guess.

[@benthleydorcin6160]

Sooooo much great information

[@travdripdrip382]

I be learning stuff!!!

[@BigBenlolz]

I wont cancel my tuning appointment for next week but I damn well will watch all this. I feel defeated though that this is the only thing I cant do myself on this damn car.

[@BigBenlolz]

Good thing the tuner did a horrible job so here I am again lmao

[@setharcher5869]

The CL RTI (Closed loop Return to Idle) settings in MEITE are key to solving idle dip. I can clutch in at 5k and it settles down perfectly. I still don't make a habit of it, but I can do it.

[@michaelbull6906]

Dear Greg peters of the car passion channel, I love you.

[@TheCarPassionChannel]

😂😘

[@theonlybucko]

I've needed this so bad. I am still having a hard time with my 1.6 turbo idle and startup after driving it when the coolant and iat is higher. Hopefully this helps

[@harleydaun3847]

Damn it greg i just got to bed at 7am... now i have to watch this

[@itchy108]

Just got my turbo nb to idle well during warmup with a megasquirt. I needed a diode on the idle control valve to get it working properly, would hum otherwise.

[@scottmason2245]

As always miata dad comes through. Thanks greg!!

[@acentricity8231]

I don't know if it was mentioned before in the comments, but I've found that batch fire injectors require more fuel than sequential. My car requires an idle AFR around 12.5 because of this. Apparently under high vacuum, when the injector fires a pulse during the combustion stroke, some of the fuel that sits in the port waiting for the valve to open gets sucked into a different cylinder. It causes some ignition events to be richer and others to be leaner which can rough idle even in the high 13's / low 14's.

[@zackdl]

3:49 Zach Hendricks, you better pay attention!

[@str8slayn1]

Yes sir!

[@sebfullick5011]

Hello from the UK! very very good explanation. i was a long term MS3 user and now ive switched to Maxxecu which i find easier to tune with, ive wired and fitted several MS ecus to friends cars and still like the product but i feel the R&D is going down hill, do you prefer ME to MS and why?

[@bvn246]

Thanks Greg for this, my mx5 needed this badly with my me221 😂

[@adrianvalella6854]

awesome video

[@Stranio34]

Took some time before I could watch it. But nice good video !!!

[@paulkimble4548]

great video

[@DJimeku]

Thank you, thank you, thank you

[@sjorsangevare]

Whats the intro music? It gets me vibin everytime! Also, great video! I don't even have a standalone, but this stuff is still very interesting!

[@TheCarPassionChannel]

Marc Torch - Dance To My Tune

[@sjorsangevare]

@@TheCarPassionChannel Thanks! Added it to my playlist to listen to while driving the Miata!

[@street_fighter_mx5]

Please more ME442 tuning videos. Spark advance/VVT tuning/Knock control/Electronic Boost control settings

[@Zesserie]

Greg: Valve, i need you to be this much more open. valve: No.. have some hats and glock skins.

[@spencerlott6729]

Thank you! Miata Dad strikes again

[@little_timgaming617]

Thank you for that intro

[@jeffreylyons1531]

You rock man

[@jarentimmer9226]

Today I learned my car dies after a pull because I drive like a dingus! Any help is good help haha Thanks for another great and well timed video 🤘

[@TheCarPassionChannel]

The motor really shouldn't die if you clutch in from high RPM, but if you specifically do that after a hard pull another contributing factor is that there's a ton of fuel in the motor when you clutch in, so that can lead to idle dipping and motor dying out. But I have found that if I can't quite get the idle right, clutching at the last second is not only an easy bandaid, but it's smooth when you get it just right, and easy on your brakes haha

[@Chimera6297]

I swapped a 1.8 into my 92 miata and kept the 1.6 throttle body. I ended up tightening that idle screw all the way until it won't turn anymore and it idles at about 1000 rpm once it's warmed up. that is the lowest it'll go, and when I put it in gear it goes up to 2000 rpm which I've gotten used to by this point. once I changed the timing belt tho it became more consistent and ran a lot smoother. before it sounded like it was cammed and misfired at idle. but I've messed with the idle so much I've decided to leave it alone lol MY POINT IS a stretched/old timing belt is a very overlooked issue. I removed the valve cover and realized the belt was LOOSE and somehow didn't skip any teeth also if it dies when you give it gas, it could be the AFM (if you have one) it kept dying, so I cut the top open with a knife and soldered the connections back together. after that I moved the wheel in the afm literally one tick mark and it fired right up n ran just fine

[@Nitrocity7151]

How would you proceed if you're having massive idle dip issues when the A.C. is activated on the stock ECU? My 1990 would dip almost 1000rpm and just die whenever I went to a stop or popped it in neutral with the A.C. activated, my temporary solution was raising the idle and adjusting the damper pot. The downside is when the A.C. is off it idles pretty high

[@CasualGearheads]

*squeee* another Pegg Jeters vid, sweet

[@chaniem.5422]

Video on how to regulate engine temperatures with fan switches, thermostat and ecu?

[@234Nick]

Here's something I've learned from owning a Cayman: Sometimes it is nice to have a steep idle drop when the car is fully warmed up instead of a gradual fall. When the cayman switches from warm up mode to ready to party mode I know it's good.

[@TheCarPassionChannel]

I absolutely hate rev hang. Shifts are SO much more fun when the revs drop like a rock.

[@scottbyrd3662]

Incredible, make the confusing easy.

[@denniscarr21]

Future video. What can be removed from the NB engine bay to clean it up a bit if you are on a stand alone and not worried about emissions.

[@grvyrdgang5672]

I would really like your input. I have an idle issue on my 98 e36 it holds idle and runs with the maf unplugged. But when it’s plugged it struggles to hold idle and stalls out. Codes are fuel trim bank 1 and p0101. There are no vacuum leaks, I cleaned the icv and have a oe maf sensor. I honestly think the culprit is that I got a faulty new iat sensor