Howdy and Newbie with a 1996 z28 problem

**screeb** · 02-15-2007, 05:25 PM

Howdy y'all,
I have a 1996 z28 which starts up just fine, but after driving it a bit it starts to idle down and stumble during deceleration, often stalling. I can recrank it OK, but the problem still persists. Any ideas as to what the problem is? It's not throwing any codes, so ODB is no help. No that's not a typo, whoever invented that system is a old dirty b****rd.
Any help is appreciated,
screeb

**DeadZ28** · 02-15-2007, 10:42 PM

Originally Posted by screeb

Howdy y'all,
I have a 1996 z28 which starts up just fine, but after driving it a bit it starts to idle down and stumble during deceleration, often stalling. I can recrank it OK, but the problem still persists. Any ideas as to what the problem is? It's not throwing any codes, so ODB is no help. No that's not a typo, whoever invented that system is a old dirty b****rd.
Any help is appreciated,
screeb

Two things Optispark and/or IAC

**BlackLT1Z28** · 02-16-2007, 07:47 AM

Optispark is such a bad word.

**DeadZ28** · 02-16-2007, 05:04 PM

Originally Posted by BlackLT1Z28

Optispark is such a bad word.

Isnt it..worst ignition system ever

**Chad97z** · 02-17-2007, 10:18 PM

bet ya a dollar the base idle screw is not set properly. read the haynes book.. Should tell ya how to do it. Probably by disconnecting the IAC motor completely and then unscrewing the base idle screw until the rpm reaches like 500 or 600 or 750. Then once the IAC is reconnected it properly adjusts it for cold and warm temps. As it is, probably the base idle screw is shut off completely so only the IAC is being adjusted on the fly and in real time to keep it at idle. If the engine is warm, and if you let off the gas suddenly, then bam there is no air because the base screw is shut, and the ECM tries to catch it from dieing by adjusting the IAC open. Thus causes an unstable idle. Has nothing to do with the optispark.