Unstable Idle

[kmidkiff]

Hey i have a 2002 Z06 with a large cam and exhaust. When you crank the vehicle the rpm jumps up to about 2000 rpm then falls to about 500 rpm and almost dies. It will then surge a couple of times then stabailize a 1000 rpm which is where the base idle is set at. what can i adjust to stabilize the idle, ive been racking my brain. It also sets bank 1 and 2 lean codes but runs a 12.8: 1 when on the throttle and about 14.8 to 15.2 a/f when crusing. and should i disable the rear o2 sensors before tuning. any suggestions would be greatly appreciated.

[SOMhaveit]

You've probably found it by now, but if you haven't, there is a tutorial for idle adjustments here on the forum.

[drdarthinvader]

wow dude sounds like you should start from scratch. go to the tuitorals section in the forum and STUDY all . im still learning,it takes months even for a mechanic like myself .

http://forum.efilive.com/showthread.php?t=4661
http://forum.efilive.com/showthread.php?t=4504
http://forum.efilive.com/showthread.php?t=2990

[The Alchemist]

To limit the startup flare of 2000rpm go to Idle step parked settings and knock 1 to 2 g/s out at the appropriate temps where the problem is that will sort that little problem. Next check IAC counts once the idle is stable at 1000rpm so see if the throttle blade needs adjustment, aim for 30 to 50 counts. Also please check what your vacuum is in KPA (thats what my brain uses ) once your idle is "stablised". If its more than 55-60KPA expect your idle to be a pain in the arse. You may need to raise the target idle to get more vacuum. Also use bi directional control to fix spark at 20 to 24 degs to see what timing suits your engine at idle then put this figure into your base spark maps.....
Hope this helps,
Mike.

Hey i have a 2002 Z06 with a large cam and exhaust. When you crank the vehicle the rpm jumps up to about 2000 rpm then falls to about 500 rpm and almost dies. It will then surge a couple of times then stabailize a 1000 rpm which is where the base idle is set at. what can i adjust to stabilize the idle, ive been racking my brain. It also sets bank 1 and 2 lean codes but runs a 12.8: 1 when on the throttle and about 14.8 to 15.2 a/f when crusing. and should i disable the rear o2 sensors before tuning. any suggestions would be greatly appreciated.