Idle tuning question.. Idle Desired AF vs. MAF

[mowton]

Dennis,

The rolling idle/clutch in has definitely gotten alot better by using the Dynamic airflow as the tune model. IAC counts are much closer now (+/- 4 counts). The only unknown at this point is why I needed to move the idle scalar from the conventional (mathematical) value of .0192 for a 90 mm TB vs the current .0285 which seems to work much better.

My initial approach was to use the MAF values, but Scott's is to use the Dynamic (VE only) which can be a frustrating trying to get the 3 amego's (fuel, timing and air) to line up after each change

As Scott said, I will get her on the dyno to tweak in the VE (street tuning VE compounds the frustration for me ), tweak out the rich decel (still have a bit of oscillation in the rolling/clutch depressed idle, and dial in the cold start/warmup open loop tables on the street. With the holidays and all, I haven't had time to tweak.

Thanks Scott for your help. Dennis, give it a shot and let us follow your progress.

Ed M

[Google]

Ed,

might try using the airflow error and changing the effective area with the scalar at 0.0192 untill iac is closer.. for some reason I am thinking it won't work on yours the same as an iac car but worth a shot.. if I remember correct the pcm will just change effective area cells and make it worse.. worth a shot though.

[DrLoch]

Ed,

I'm just at the very very beginning of the tuning process and have a lot to learn. This is an LT with a 24x EFI conversion to 411. 383 forged bottom end, trick flow 195 heads, comp HR, shaft rockers, CIA headers 3" exhaust and a F1 Supercharger..... to throw out a few items I've added to the mix. I just got it fired up between thanksgiving and Christmas. While it is running and idling I have a long way to go in the tuning process. The first issue was getting through the case learn process, I was having issues and Google was the person who gave me the answer I needed to get through that process. The initial idle was to high and I was using the beta version. Scott suggested getting the idle as low as I could get it and use the non beta version, that worked. Right now VE is the major area that needs addressing right now but I don't have wheels on the car right now to get the street tuning of the table done. I may be able to get some of it done as it sits but will need to get wheels and tires on it to do the most good.

I found your post doing a search and was trying to understand the information Google was providing on Idle Desired/Dynamic and airflow error....... I shot him an e-mail asking a few questions to which he answered. I'm not afraid to ask questions if a search doesn't give me the answers I'm looking for or I don't understand the data or results I'm seeing but as I've said I have a long way to go on this.

This forum has a lot of information available if you can structure the question correctly when doing a search.

Dennis

[ctd]

"The only unknown at this point is why I needed to move the idle scalar from the conventional (mathematical) value of .0192 for a 90 mm TB vs the current .0285 which seems to work much better."

I think part of the answer to this question is the idle air demand due to the large cam & cylinder heads. The math does not account for an engine that demands more air, the math is based on the stock motor idle air demand. I'm hoping I'm a least partially correct with this assumption.

I have a question.

How do the IAC counts come into play with the C5 Throttle Body? I understand with the cable TB & IAC, not with the DBW.

Then there is even mention of desired IAC? Yikes! mowtown's car is an ETC which I thought did not use IAC.

Would somebody please explain what the IAC does with the DBW & what I should look for?

I have a 102 mm TB for my new 416, previous threads & posts indicates this TB can be a bit nasty to get running nicely.

Thanks

[greenfrog]

Hi Google, your interchange with Ed, re scalar ,idle airflow, maf,hz, ect is really intense, really need to get my head around it. The issue in my vehicle 01 c5 427 m6, is idle/rolling idle flare.Although I run efi live, it seems many senior/advanced tuners run both hpt & efilive. Can I send you a copy of my tune, perhaps with a log or two, that you specify the pid list. Even a log file of your stats would be very apprecative. Also any other posts that may help me. Have tried to get assistance from the efi live tuners/posters,they do not offer the help like I see in this forum, cheers, greenfrog.

[ctd]

greenfrog, this thread is from 2011 my 416 stroker with a 102mm TB is running very well. No issue that you mention, following some of Google's theories helped to settle it down.

Ed's contact information is in his post's, maybe give him a try.

[kingtal0n]

I have a question that this thread seems like it pertains to...

I am running NO MAF. When I first start the engine, it looks for the maf initially, and wants to die right away. After about 3 seconds it "fails the maf" and runs perfectly fine in SD mode. It does this every time I Upload a new tune so it is really annoying.

Where/what table do I adjust so that, while the ECU is "looking for a maf", it gets enough fuel to run normally for that 3 second window? I thought it was the primary maf table but I tried adjusting the first couple cells up (more airflow) to no avail. Help please!

[07GTS]

I have a question that this thread seems like it pertains to...

I am running NO MAF. When I first start the engine, it looks for the maf initially, and wants to die right away. After about 3 seconds it "fails the maf" and runs perfectly fine in SD mode. It does this every time I Upload a new tune so it is really annoying.

Where/what table do I adjust so that, while the ECU is "looking for a maf", it gets enough fuel to run normally for that 3 second window? I thought it was the primary maf table but I tried adjusting the first couple cells up (more airflow) to no avail. Help please!

look at the maf tests sometimes it can be looking for a set time before it fails it just lower them so it fails quicker, or fill in more of the maf table up to idle airflow