About to throw in the towel nailing down idle

[Michael_D]

I just review actual idle spark in my chart view and compare that to the idle spark table. If you have min air set too high, you will see the actual spark value lower than what's in your idle spark table. Play with this, and you'll see.

I have not looked for a PID.

[gmtech16450yz]

Idle Adapt Advance is the PID you want to log and put in your chart display. It will show you exactly how much timing it's adding or taking away to maintain the desired idle. Obviously 0 is the desired goal but realize that it will fluctuate normally. You just don't want it oscillating between large numbers like -10 then +10. Mine doesn't go much beyond -2 to +2 normally. Watching this value is VITAL to tuning any of this idle stuff.

[5_Liter_Eater]

That's what histo 11 is set up for in my config.

[rio95]

Yeah but I haven't got airflow changes to affect idle rpm or actual timing yet. Every aiflow change I've made has given me an average idle adapt within 0.4deg of zero. I guess I'll give it another try tonight....

[5_Liter_Eater]

Don't do anything with forcing the spark idle on or off in the VCM controls this time. For reference I was playing with that the other day and it's still backwards. Turning spark idle ON in VCM controls turns it off.

[5_Liter_Eater]

What I would expect to see (while not moving), is the idle adaptive spark to be pretty negative if you've doubled the airflow final minimum.

[rio95]

I will try it with and without adapt and report back tonight. This has really been annoying me so I want to try this again asap. Been on vacation for five days.

[5_Liter_Eater]

I mean don't do anything with VCM Controls.

[rio95]

I mean don't do anything with VCM Controls.

Yeah I know what you meant. I shouldn't have said that.

This time I left adapt on and didn't command idle or do anything in VCM controls. This still makes no sense!! What the heck is my problem?



LOGS:

idle - current tune.hpl
idle - double aiflow.hpl
idle - triple aiflow.hpl

[rio95]

Tunes:

15-8-3 Justins corvette - current tune.hpt
15-8-3 Justins corvette - double airflow.hpt
15-8-3 Justins corvette - triple airflow.hpt

[5_Liter_Eater]

Well looking at the logs it wants to take 4-6 degrees out of the 1000 RPM cell and the 800 RPM cell looks perfect. Doesn't make sense. I haven't looked deep into the tune but are the other settings in engine/idle/rpm/adaptive idle ~stock? The only thing I can think is something else is able to correct for the incorrect airflow final table entries that the adaptive idle spark isn't needing to. Regardless you can see that the numbers in histogram 10 are relatively the same in all three logs and those numbers (minus 20%) are correct.

[rio95]

I meant to also say that when I doubled the airflow the idle would hang pretty bad and even worse when I tripled the whole table. The idle was nice and steady with all airflow settings though but it seemed to dip still at all airflows when I would drive the car so I'm probably going to have to adjust some other tables, but I need to figure out the airflow table first....

All the logs were in neutral with e brake on.

[rio95]

Well looking at the logs it wants to take 4-6 degrees out of the 1000 RPM cell and the 800 RPM cell looks perfect. Doesn't make sense. I haven't looked deep into the tune but are the other settings in engine/idle/rpm/adaptive idle ~stock? The only thing I can think is something else is able to correct for the incorrect airflow final table entries that the adaptive idle spark isn't needing to. Regardless you can see that the numbers in histogram 10 are relatively the same in all three logs and those numbers (minus 20%) are correct.

I don't really think the 1000rpm cell is accurate though because that's well above my target idle. It probably just got a few counts from minor surging. Definitely not steady state data. Adaptive idle tables are all stock. The only changes I've made for idle are target rpm, timing, and airflow.

[5_Liter_Eater]

I meant to also say that when I doubled the airflow the idle would hang pretty bad and even worse when I tripled the whole table....
All the logs were in neutral with e brake on.

Well I don't know why the second part of the process isn't working for you, although I've never tried doubling or tripling the numbers I got from the first step. The 1000 cell makes sense if it was just due to it not being able to get down to 800. But the hanging idle when you raise the min airflow show that the numbers from the first step are reasonably right.

So this is on an automatic? Again, I've never tried this process on an auto.

[rio95]

Well I don't know why the second part of the process isn't working for you, although I've never tried doubling or tripling the numbers I got from the first step. The 1000 cell makes sense if it was just due to it not being able to get down to 800. But the hanging idle when you raise the min airflow show that the numbers from the first step are reasonably right.

So this is on an automatic? Again, I've never tried this process on an auto.

2007 z06 manual

I have no idea how I'm the only one having this issue. I agree my first numbers are probably close due to the way it behaves but i doubt its optimized. I'd like to come up with numbers using some methodical approach rather than just trial and error and using judgment but I just might have to do that if no one else can explain this mystery.

[rio95]

Could it be fueling affecting things? Am I supposed to do this in open loop or something?

[5_Liter_Eater]

It should be done however the car will be run. I've always done mine in closed loop. Do you get any hanging, dipping or surging with the derived numbers?

[Michael_D]

How long are you letting the engine idle in each rpm cell? It takes mine about five minutes per cell to really find stable average values after trims settle.

Do this in CL, AC on. After you flash a new cal, make sure the car is not in its"lean after flash" mode. And yes, it happens even doing min air table adjustment.

[edge04]

I got my A/F all dialed in running MAF and VE. This is a E38 computer. I've been going through this procedure and it does seem as though I am making progress as the idle is getting smoother and I also noticed that my TPS% has come down. Any way here we go

1. First. My Final Airflow minimum looks to be in lb/min so I changed histogram 10 Idle Airflow to lb/min as well. See pics. Is that set up correctly?

2. I noticed that when logging histo 11 Idle adaptive spark I always come up with about the same positive number under 800 rpm as I do in a negative number under 1000 rpm. So does that mean that 900, where I have my idle set at, is close to zero and I should stop? Because the 800 is always positive and 1000 negative the table doesn't flow. Also see pic

3. I have my idle spark set at 26. Too much or too little or good for a cam with these specs ADV DUR INT 279 EXH 297 DUR @ .050 INT 227 EXH 243 LOBE 114. Seems to be good and guess I can experiment with lowering and see what kind of effect it has.

Airflow Final Minimum.png

Idle Adaptive spark.png

Idle Airflow histo.png

[edge04]

Well hopefully can still get some answers to above but I haven't been letting the "rich after flash" go away so I guess I'll start over. Man this can take awhile as its usually 15 mins of driving or so before the trims settle.

How long are you letting the engine idle in each rpm cell? It takes mine about five minutes per cell to really find stable average values after trims settle.

Do this in CL, AC on. After you flash a new cal, make sure the car is not in its"lean after flash" mode. And yes, it happens even doing min air table adjustment.