Tuning the IAC Effective Area - MAKE THE SCANNER DO THE WORK!

[@242bleek]

Great video, im gonna try this tomorrow. I have a single plane and 4150 tb. VE tuning is all done and idles fairly steady but the effective area cant be right. My desired idle airflow slowly drops to zero as do the steps when its fully warm and it still holds idle well but if I close tb screw to bring steps back up it will stall. I figured this had to be the issue.

[@GnarlyBlade]

Is this procedure performed after logging Dynamic Airflow vs ECT and making corrections to the BRA table's in Park / In-Gear? Assuming the VE table is within ~5% in idle regions. I appreciate all of the information you shared regarding GEN III tuning. I've been binge watching these videos. Hope all is well.

[@Good-Enuff-Garage]

Doc delivers the goods again!

[@split150]

Could you explain what's in your MPG math calculation? Looked interesting in the background.

[@BearFulmer]

Thanks for helping get my iac inline. Works really slick

[@realbigdady]

Very nice thank you. I have never had to deal with this iac tuning before and this helped a lot.

[@ChopperDoc181]

Thank you. I'm glad it helped. Idle in general with big cams and lots of mods is difficult to say the least. Thank you for the comment.

[@Go69]

My question is.... Is it necessary to adjust the IAC STEPS vs Effective area on a DBW-or drive by wire car? The graphs I set up for my DBC truck DO NOT WORK for DBW cars???? What gives? Is it not necessary to adjust the IAC Effective area on DBW vehicles? This has always puzzled me... Well this and BASE RUNNING AIRFLOW on DBW cars as well.. The RussK idle config does not work on DBW cars because there is no IAC so how do we verify that the throttle body flow area is correct? Or, am I over-thinking this stuff?

[@OgTheRealOne]

Hey Chopper Doc, thanks for this info! I'm trying to figure out why my VCM Scanner is showing 310 for Idle Air Control Position? It has no output, stays on 310.

[@ChopperDoc181]

Have you tried opening the blade up? It could be just maxing out, or you have a bad IAC.

[@OgTheRealOne]

@@ChopperDoc181 I have not tried opening the unit itself, I have cleaned the TB and ensured it has free movement. The Idle Air Control Desired is moving frequently in the scanner, but IAC Position is static on 310. I do have an X link installed if that is pertinent here.

[@ChopperDoc181]

What I meant was opening up the TB blade with the idle set screw and seeing if the IAC closes. If it doesn’t there’s probably something wrong with your IAC or the wiring.

[@OgTheRealOne]

@@ChopperDoc181 I see what you mean here, with that being said let me ask, this process is for both cable and ETC, or just cable? I’m on a ETC setup.

[@ChopperDoc181]

It’s just for cable. If you have a ETC TB the computer opens and closes the blade to control the idle. There’s no need for an IAC motor in that setup.

[@timothymckee7723]

So when I log my iac control position it’s stuck on 310 but the iac control desired position fluctuates as rpm’s raise and lower. So I’m getting no data populating. Is it safe to say my iac has failed? And would that create a surging effect at low idle. I had to raise my idle to 625 just to keep engine from surging.

[@ChopperDoc181]

Have you tried adjusting the blade? Opening it should bring the counts down. I would start with that.

[@bigbert1119]

When you pull up your old graph you have IAC corrected as a number(). How do you go about doing that?

[@ChopperDoc181]

You have to add a user math to the scanner which produces the correction.

[@kaeuh7124]

Phenomenal videos, in my logs the IAC has remained open while on throttle and increases with TPS%. Goes as high as 238 and stays there all the way to 100% throttle. What is commanding this?

[@ChopperDoc181]

A few tables can affect this. First one that comes to mind is the throttle cracker. There is also a throttle follower too, but that’s off throttle decel. All and all though, the IAC really has no affect on anything when the throttle is open. The problems with it are always prevalent when the blade is closed, and you’re having difficulty with cold start, or “cruise control” caused by the throttle cracker. I can’t tell you exactly what is commanding that particular number. Like I said once the throttle is open any IAC formulas from the PCM really are quite irrelevant.

[@Loucfr]

Question; if my VE was spot on before doing this procedure why is it so off now? Do I need to redo my VE?

[@ChopperDoc181]

Yes, because the amount of air being calculated from the IAC table is having an effect. It shouldn’t require a lot of tweaking, and it should only effect a few cells at most at idle. Once out of idle routines VE should remain fairly accurate.

[@Loucfr]

@@ChopperDoc181 The whole table isn’t supposed to be changed right? Just the cells mostly used from a cold start to a hot idle usually 40-200 or so? That may be where I went wrong. I adjusted the cells throughout the entire table. But my VE was drastically off after this procedure.

[@Guiohms.m50]

Hi, I have a 11° Overlap cam, I tuned VE with a Wideband to -5/+5% (and take off 10% at idle for the camshaft), MAF, Spark, EIOT, DFCO, set the Idle in PE for hybrid tune (OL idle and CL part throttle), min transient, crackers, follower and rolling idle. But I still have a dip coming at stop. I noticed my Idle Desired Airflow goes really low when I'm rolling and coming at a stop then the rpm dip and while it reach the target idle it go back to 3-4grs higher. My Dynamic and Idle Desired (while rolling and coming at a stop again) don't match. I don't know if it's supposed to match while rolling but anyway, IAC count are my last hope. Do you think it's that? I use your method, but it seem to lowering the data everytime I log. Is it normal?

[@ChopperDoc181]

The desired and dynamic will almost never match after you tune it. When conditions change so does that number. Try increasing your RAF table in gear. This method is for getting your IAC stable, and so it works for cold starts. It will really only match the day you tune it.

[@Guiohms.m50]

@@ChopperDoc181 Yes but my STIT will bring back the RAF table where it will belong, so it will dip again..

[@ChopperDoc181]

Is the STIT learning maxed out? In reality these are the LTIT’s, but worth a look. It will only go as high as it’s allowed to remember. Stock are set to 2 g/s max trim learning. Worth a look. With bigger numbers in airflow bumping up the max learning isn’t a bad idea. For undershoots, my first correction is actually the spark tables. Have a look at the changeover speed (idle/rolling spark vs mains) and see if the speed corresponds to the dip you are seeing. These are your spark table selection tables. Typically this speed is about 4 mph. Spark changes torque on the next cycle, so it’s much faster than airflow changes. A well mapped spark table that’s blended well between selections (main vs idle) will run pretty smooth without need for playing with the IAC settings. IAC is firmly in the “fine tuning” area of the tune, specifically for better cold start and run behavior. Significant dips or stalls are fairly serious issues that also imply a bad setting elsewhere in the tune. Spark is always how I correct hangs and dips. Air helps, but not as much as spark does. Be accurate and only adjust the area needed and blend. Go a few degrees at a time until it stops doing it. You can use the scanner to play with spark too to dial it in faster.

[@Guiohms.m50]

@@ChopperDoc181 No one are maxed out. The STIT goes a little bit negative and LTIT are disable for now, when LTIT are enable, they make things worse. I took a look at the sparks and it seem to be the culprit. When I clutch in and brake the rpm fall from 2500 with 41° to 25° fast. Than the rpms goes below the Idle rpm. I tried to smooth the no throttle area to idle and now it's 33° to 25. It's less but still too much drop. Tomorrow, I'll try to bump the Idle area to 28/29, smooth and let the Idle sparks to 25° and separate the Idle sparks to main sparks as factory did to see if it's better

[@andygibbonsband]

Could you reduce the decimals of the factory column axis values and then copy and paste those values to build the histogram?

[@ChopperDoc181]

You can, but you will get values in between them because they are pretty far apart. So best if by at least 5, and even less in high traffic areas where it likes to sit at idle, etc...

[@evcass69]

What causes discrepancies between DynAir and Idle Desired Airflow? Right now my DynAir is 3-5g higher at cold start all the way to 235*F even though my VE error shows

[@ChopperDoc181]

Pretty sure I just answered this one on tech. The desired may change based on different conditions. The BRAF defines what the IAC values are, the IAC effective determines what "desired" values actually are, essentially, so really, the BRAF controls that number, or it's range at least. Start with the BRAF, and plot either "desired" or dynamic. Personally I prefer dynamic, but desired works too. Get the idle smooth when it's warm, then adjust the IAC table slowly across to get the range you want. Don't change the limits, as in 0 or 310 areas. Slope should be fairly linear, like the MAF. Other things to look at are the fuel and spark. These things play hell with idle. If you have huge injectors, lower the transient min mg to .010 or .015. That will help big time at idle. Mind you all of this is done to get cold starts to work. It took me a long ass time to get it right the first time, but it actually works now, starts on it's own and idles at 750 warm.

[@evcass69]

@@ChopperDoc181 My MAF is now dialed in from idle (I pushed it down to 600RPM using the special controls) to 8000Hz (clutch problem prevents me going higher), and VE is dialed in through roughly 4000RPM. RAF was dialed in from multiple cold starts using IdleDesAir because DynAir wasn't giving me good manners. DynAir and MAF g/s are now within 5% of each other during RAF calibration logging. I wasn't having problems with cold starts, but I'm OCD, so I changed the IAC table per the video, then had a problem with idle; STIT was now +5-6g/s. I blindly added 6g/s to RAF from 68-284, now it's behaving better but I'm curious about the remaining process. Do I need to re-learn RAF, then re-learn IAC, and keep repeating that process until a certain point?

[@michaelbaskinmichael9862]

Chopper what’s up I’m the guy who was battling the bucking think I got that under control, now we have that dreaded hanging idle it’s so weird just seems more random . I changed idle control and iac motor but did nothing I had the blade open some but it was taching to high so I back it down now I order new throttle body to a 92 mm with adapter plate any tune suggestions ?

[@ChopperDoc181]

Try pulling timing at the hang, and above and below it. Remember to smooth it in, you don’t want to spin it down too fast, otherwise you may set it up for an undershoot and potential stall. I pull 3-5 degrees out at a time when it hangs. This reduces delivered engine TQ.

[@thomasjohnson1142]

So the iac being out will also cause it to gain speed when you put it in gear without pushing the throttle correct? And would have to make the same changes ?

[@ChopperDoc181]

No, this is all done at idle, primarily for cold starts and stability. The problem you are having is an adder like throttle cracker. You can zero the problem areas out on that table and it should fix that “cruise control” effect you are seeing.

[@thomasjohnson1142]

@@ChopperDoc181 thank you I’ll try that the only effect I had on it was the iac changes but I will try the throttle cracker I had to edit I see 0 out the problem areas gotcha

[@Busa0069]

What does it mean when the corrections are in the 500 to 600 correction range ? Does the throttle blade screw need opened up a little ?

[@ChopperDoc181]

It means your dynamic air and desired are very far apart. If it's that far off, it's usually near the ends of the scale. Don't exceed 310 as a number, since the computer doesn't seem to actually recognize anything above this. You may have to revisit you RAF table and VE to get them to line up a bit better. I use dynamic air values for my RAF table instead of desired, which are straight from the VE calcs. Then once it's all good, I correct the IAC table and revisit the RAF as needed. It can be a little tricky, and any blade adjustments are going to mess with everything.

[@storminnorman1932]

How is your method different from the "Russ K" method for example ?. Thanks for the vid

[@ChopperDoc181]

The Russ K method is intended to setup the Base Running Airflow table by plotting "Idle Desired" vs "ECT" on cold starts. Personally, I have stopped using that method. Here's why: The BRAF table essentially defines what the values of the IAC effective area actually ARE in airflow estimates. "Desired Airflow" is actually what the PCM "thinks" the airflow is at "x" IAC number, which is based on the BRAF. So it is kind of a circular problem if you use "desired" to calibrate what is essentially "desired" if that makes sense. Instead of plotting "desired" vs "ECT", I just use my dynamic numbers instead, on the same table. This is provided the VE is solid, and the car is running well at temperature. Once my calibration looks good on VE at temp, I go ahead and plot "dynamic vs ECT" on a cold start and plug those numbers in. Mind you this is BEFORE you start changing the IAC values. Now the PCM has the REAL airflow required to run the car, as in dynamic. After I have the BRAF calibrated using dynamic values, I go ahead and then tell the PCM what the real effective area is using the method in the video. Basically once the "idle desired" and "dynamic" values are the same or close, the IAC is properly calibrated. The rest of the settings are in the blade (mechanically) as I have found further adjustments and tweaks are often needed. I also installed a set screw on my adjuster screw as a sanity check lol. Once it starts and idles on its own without help from the pedal, you're done. Check it on cold days too, as this will change things, but if it passes the cold day test without help, don't make further corrections, since the values for dynamic air have a lot of factors, and there just are not enough tables to account for everything. What that means is these "corrections" can change under different conditions. If it works though, stop messing with it lol.

[@randyw7342]

Great video. I’ve just started tuning my setup. Followed your setup for logging but mine throttle position shows 0.0% while yours is 0.4% don’t know why yet and my readings start at 104 @ 62 then goes up from there. Any help would be appreciated. Thanks Randy

[@ChopperDoc181]

The throttle % just seems like an oddity to me, but I’ve seen it many times. It’s not a serious issue. What readings are you referring to?

[@randyw7342]

ChopperDoc181 Thanks for replying , I was referring to Desired IAC steps vs Desired idle Effective Area. But then you mentioned the VE tables if it’s off then this won’t work out? So guess need to get VE first then come back to this part? I’m a newbie on hp tuner. Thanks Randy

[@randyw7342]

Can I tune VE without a wide band ?

[@ChopperDoc181]

@@randyw7342 I’m really sorry for the late reply... yes you can tune VE up to the PE areas using stock O2’s. Set the closed loop enable back to stock and use the error as your correction. Yes it’s doable, however don’t do anything in PE this way as that’s OL by default, meaning that stock O2’s are disabled in PE.

[@RAWRMotorsports]

Does this still apply to DBW

[@ChopperDoc181]

No, IAC only.

[@michaelbaskinmichael9862]

Don’t believe it’s in timing it’s pretty smooth already but I will try I thought maybe a old throttle body acting up or maybe maf , but I will try the timing curve and see , thanks chopper let you know

[@firebirdtransam17]

great info best i have seen on youtube

[@timvandyke5358]

Thank you so much for this, have learned a lot!

[@carguytim9913]

I’ve done everything in your videos and my car still surges when coming to a stop, can u do a video on adaptive idle ?

[@ChopperDoc181]

Try reducing your min fuel mg under the transient fuel tab down to .010 or so... it will help with idle rich spikes... note that I’m quoting the decimals here from memory, so I may be off a little. Stock it’s something like .046... again, decimal is from memory. Whatever the value is, keep the decimal in the same spot and reduce it to a value of 10 or 15 instead of 46. If that doesn’t work, pull some timing out in the trouble area, as I’ve noticed that also causes surges... bad. Approach number three... lean it out on that area on the VE (especially if you have a cam with overlap) as you may be encountering a false lean. In addition to this, if you are in closed loop, it may be chasing its tail trying to meet stoich with skewed numbers caused by overlap. If this is the case, put it in open loop using PE tables, and simply set the target to 1.0 in these areas. What that does is enable OL through PE, but won’t change the fuel target in the RPMs you don’t want it to, particularly idle. Typically it’s set up to 1200 or 1600 on the table with a correction of 1.0 and a TPS enable of 0, aka, PE enabled at idle. Also note that the MAP enable must also be met, so make sure it’s under your typical average idle MAP numbers.

[@carguytim9913]

@@ChopperDoc181 thanks for the help. Do you have Facebook? Maybe I could send you a couple messages about it, I promise not to bug you too much haha. I’m in open loop speed density only, not using maf or o2s. Also I have my ve set to idle at 15.5-16 afr

[@ChopperDoc181]

I do have Facebook, but I’d rather share that offline in an email or forum. You can find me on LS1 Tech as simply ChopperDoc... I try and get back in timely manners, but sometimes I forget so for that I apologize.

[@carguytim9913]

@@ChopperDoc181 I understand completely, I don’t get on ls1tech, maybe you could send me a message instead? I’m pretty desperate and that’s the fastest way for me to communicate, I don’t check my KZbin notifications often. If you want to, my name is Tim Artrip and I’m in va. Shouldn’t be hard to find and I’d really appreciate it, thank you

[@jjjjjj9284]

Well done mate great bit of info cheers

[@adriancervantes19]

You my man are a god thank you so much for this !!!!

[@hooligans_garage7465]

Very good video thanks!!

[@konkan5728]

Is possible to use this on a Gen 4 ECM?

[@ChopperDoc181]

Gen IV’s are electronic, so not too sure how this would be useful. The final airflow minimum table is exactly how it sounds. If you need more air at idle, simply increase the number and it will open the blade more.

[@konkan5728]

@@ChopperDoc181 Thank you! New to this and found the way you explain things to be very easy to follow. I'm looking forward to whatever else you may have in the works. Hopefully gen 4 stuff!

[@seanpaul8584]

Would have been nice if you saved the values from 1 to 300 or what ever you used paste it in the description.

[@ChopperDoc181]

Haha, that’s actually not a bad idea. If I get a chance later after work maybe I’ll do that.

[@nickoD509]

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[@seanpaul8584]

@@nickoD509 thank you sir

[@916chevyboy]

Awesome

[@RAWRMotorsports]

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