I had a new opti and water pump installed in my 94 Z28 which solved my rough idle/lunging problems for over 8 months. All of a sudden my car is starting to idle rough again and it actually stalled at a stop light this morning.

Has the new opti already gone bad or is it something else that could cause the rough idle. The one thing that is wierd is that the car idles worse when the A/C is on.

Thanks in advance for any helpful info you can share :-D

 

The PCM controls idle using the IAC valve on the bottom plate of the throttle body. Might be worth checking to see if there is dirt/carbon in the valve or the TB passages. If you have access to a scanner, you can check the IAC valve "counts" at idle, to see if it is set in the correct range, and is respoinfding properly to irregular idle.

 

Whats the best way to clean the TB and its passages?

Will cleaning it solve the problem?

 

Does anyone know the best way to clean the Throttle body?

 

Quite a few people seem to like Seafoam's Deep Creep to clean out dirt/carbon buildup in the throttle body.

 

Can the seafoams deep creep be purchased at pepboys or autozone?

 

I know for sure NAPA and O'Reilly carries it but couldn't tell you if Pepboys or Autozone does. You may just want to give them a ring.

 

I just checked and these is a bunch of black grime in the bottom of the TB. I havent had a chance to the stuff at pepe boys or autozone so I scraped alot of it out.

The car idels rough even when its cold and it really gets bad as soon as the AC is turned on.

I remember when the opti was going bad it really didnt get noticable until the engine warmed up.