how get pcm to use idle under/overspeed instead of cracker airflow while rolling?

[ericwilloughby]

2002 Trans Am, 411 pcm I believe, 6 speed manual 230/235 comp cam with 5 degrees overlap. Is there any way to get the pcm to use idle under/overspeed instead of cracker airflow to actually control the idle speed while the vehicle is still rolling? I don't understand why there wouldn't be any ACTIVE idle control when the car is rolling. The only thing I can do to keep the engine from dieing when I turn into a parking spot quickly is idle the engine up with the cracker airflow settings but idling into my gargage at 5 in the morning at 1100 RPM sucks.

[mecanicman]

http://www.hptuners.com/forum/showth...1-Rolling-Idle

[Mudweizer]

Why do you have your Rolling Idle Speed all at 0 rpms and your rolling idle enable speed at 255 mph?

[ericwilloughby]

Those are factory settings. I tried Setting rolling idle it did nothing. But I wasn't aware of the enable. I'll try that.

[ericwilloughby]

http://www.hptuners.com/forum/showth...1-Rolling-Idle

That didn't help at all

[mecanicman]

if that didn't help maybe you should post your tune again, cause the one you did is all 0s where that data should be.

[mecanicman]

This with info in link should have it working.

[ericwilloughby]

It seems to me that rolling idle doesn't do anything. Except maybe revert to the throttle cracker table. I set the enable, set rolling idle to 1000, and zero'd throttle cracker. No idle control. Certainly didn't try to maintain 1,000 rpm. Died every time I pushed in the clutch. Wouldn't idle well until the car came to a complete stop and then the over/under speed took control and things were great. Why the hell doesn't it use that all the time instead of jerkin with the cracker tables?

This is where the jpg should be. I don't know how to display it with this software.

Damn, I just noticed, maybe I should disable the cracker. I'll try that this afternoon.

[DSteck]

Rolling idle is what gets used when you push the clutch in. Putting the shifter in neutral uses the cracker table.

I've had some vehicles where I could disable throttle cracker completely, and it would use adaptive idle, but I've had better results with properly setting the throttle cracker and rolling idle systems.

[Mudweizer]

Do you have pin 32 of the blue connector hooked up? (CPP Switch Signal) (wire is grounded until you push in the clutch)

[ericwilloughby]

Beats me? It's in the oem configuration. I could check it.
So...I'll disable the cracker table instead of just zeroing it and see...

[ericwilloughby]

well, this is a problem. The explaination of the rolling idle section says, "above this speed the throttle cracker rolling idle mode is enabled in neutral or if the clutch is depressed". I don't want throttle cracker.

I don't understand the relationship between cracker, rolling idle, and adaptive. I want whatever 0 mph is doing but I want it all the time.

[ericwilloughby]

I enabled and disabled both rolling idle and throttle cracker but It never attempts to idle at the 1000 set in the rolling idle table. Best it will do is go to the throttle cracker tables. Damn it.

[cesar]

on enable throttle cracker just set the speed to 33 and 33 for enable and disable and it will idle while coming to a stop from 33 mph and down

[LSxpwrdZ]

On manual cars I don't like setting the enable/disable speed to much over 4-5mph because if you engine brake alot to allow DFCO to enable when you get inside that window of speed with the engine braking in gear the idle adapt will kick in and start pulling idle air and as soon as you stab the clutch in the idle adapt is already negative and usually will cause a stall since it can't react fast enough.

Rolling idle and Cracker are basically the same thing, only rolling idle is adaptive and in a manual car ONLY active when the clutch is pushed in. Be sure to log cracker when you are doing logs so you can determine if/when its active.

[AdsoYo]

I don't understand the relationship between cracker, rolling idle, and adaptive. I want whatever 0 mph is doing but I want it all the time.

x2!

[LSxpwrdZ]

If you want that then simply zero the cracker and follower tables out and then set the enable/disable speed to 250+mph then once tps reaches below idle zone and lower than the TPS setting in the follower table to zero out the follower it'll kick into idle adapt and use spark and PID idle control.

[mowton]

I have mine set to about 10 mph and it works for parking lot driving. I agree that there is a more sophisticated way to fix this but in a pinch it should help. I also know that each OS/year is different (TC/TF disengage clutch in etc.) as well as the particular platform....this is from a 2004 Corvette MN6 with a H/C/I modified LS2. Cam is a just a bit bigger than your setup, DBW and TC/TF disengage when clutch is depressed. Copy over the values you will need and give it a shot.

Hope it helps...

Ed M

Update -- Tune has some strange items...0's in VE table, cylinder volume not correct for 6.0, idle adapt airflow maxed (points to tuning may not be complete to set idle trims, min air etc), may be over fueling at idle/rolling (need to see log to determine if EOIT, transient milligram etc need tuning) etc. Should disable STFT open loop, You may be trying to cover up for other tune issues, sorry.

[ericwilloughby]

I changed from 5.7 to 6.0 3 weeks ago. Forgot to change cyl volume. Does anything actually reference that value?
0 in high vacuum VE section is to stop fueling during shifts. Trying to get rpm to drop more quickly.
I just added 10% to transient to fix a bad lean stumble when engine is cold. U think to much or to little still?
Stft is enabled asap because the o2's can control the afr much better than open loop.
I set idle adapt airflow to a wide range to alow it to adjust to where ever it needed to be when I was tuning idle airflow.

Correct me...but isn't idle airflow adapt nothing more than fuel trims for idle?

[mowton]

Yes, but based on certain conditions, the trims may deviate quite far from normal and when you get back into the car (after a cool down), they will be the starting setting that the pcm will idle with and they could be way off. You wont begin to update this settings until you reach the temp setting to enable adaptive idle learning. You should never have to deviate +/- 8 g/sec for idle air. That is why I said I think you need to "tweak" your idle settings. Russ K has a great .cfg and procedure to accomplish this. A quick search will locate it.

For the fueling during shifts, try cutting the min fuel milligrams in transient fuel section in half to see if that helps.

Ed M