H/C Z06 has trouble finding idle coasting to a stop

[Scooter70]

I just bought a new car (2001 Z06) and it's having an issue finding idle when coasting (clutch in) to a stop. It drops to 500rpm, blips to 1500, back down to 700, up to 1200, .... , until it settles back at 1000. It usually doesn't stall but it's irritating. The car has heads/cam/headers/FAST92/ported LS2 throttle body. The car runs well and doesn't surge other than this one idle condition even though it has an almost stock VE table.

Anyway, attached is a log that shows the issue. I'm hoping that there's an idle related table that I just need to tweak to fix the idle hunting so that I can then do proper MAF and VE tuning. It's been a few years since I've done any real tuning on a modified car so I'm trying to get back up to speed.



Any tips would be greatly appreciated.

Thanks.
-Matt

[printmanjackson]

sounds like it wants more air. these drive by wire cars are a bitch ... just saying

[Scooter70]

I noticed how Dynamic Cylinder Air was an inverse wave of the rpm but wasn't sure which one drove which. I was planning to try RussK's Idle Scan next to see if that helped out.

[mrvedit]

I had a similar problem and solved it this way:
1. I reduced my Idle advance to 24 degrees
2. I increased the "Idle Adaptive Spark Control" both Overspeed and Underspeed tables to reach +/- 8 degrees.
3. Under Engine->Idle->Idle Airflow, I increased all the "Adaptive Idle Airflow" values.
The quickest way for the ECU to stabilize the Idle is change the amount of ignition advance. However if the advance at Idle defaults to e.g. 30 degrees, increasing it won't speed up the engine any. Therefore decreasing it to e.g. 24 will help as the ECU can then add more advance.
I know that I probably changed more things than I needed to, but the car wasn't drivable with the idle wandering between 500 and 1500.
(I'm just a novice taking a stab at this.)

[detroit]

I had a similar problem and solved it this way:
1. I reduced my Idle advance to 24 degrees
2. I increased the "Idle Adaptive Spark Control" both Overspeed and Underspeed tables to reach +/- 8 degrees.
3. Under Engine->Idle->Idle Airflow, I increased all the "Adaptive Idle Airflow" values.
The quickest way for the ECU to stabilize the Idle is change the amount of ignition advance. However if the advance at Idle defaults to e.g. 30 degrees, increasing it won't speed up the engine any. Therefore decreasing it to e.g. 24 will help as the ECU can then add more advance.
I know that I probably changed more things than I needed to, but the car wasn't drivable with the idle wandering between 500 and 1500.
(I'm just a novice taking a stab at this.)

sounds like a few stabs at it...I would try RussK's idle stuff it might be alot simpler like it just needing more idle air in gear, but with a stock VE you might just go ahead and bump the idle and go thru the VE table THEN do the idle stuff.

[edcmat-l1]

How big of a cam? Getting the VE dialed in will help alot. You've got other issues, but I'd start there.

[ultimate3800]

Also you can play with throttle follower. I did that after all of my other tables were in order and it fixed it for me. The real time tuning really comes in handy for this

[detroit]

Also you can play with throttle follower. I did that after all of my other tables were in order and it fixed it for me. The real time tuning really comes in handy for this

before he starts any of the fine tuning he needs to model the air...tune the VE.

[Scooter70]

How big of a cam? Getting the VE dialed in will help alot. You've got other issues, but I'd start there.

236/238 .601/.605

before he starts any of the fine tuning he needs to model the air...tune the VE.

That's what I'm going to do. I'm in the process of putting together a file to start from fresh and properly dial in the VE and MAF.