Well my rough idle/high idle has finally gotten to me. It'* annoying and I know it'* not supposed to be this high. In all the time I have owned the car, it has never, ever idled below 1000. Before anyone asks, yes the TPS is at the correct voltage, no I do not believe it'* a vacuum leak, as it was idling like this when the previous owner bought it (petraman), and I do have a light dimming problem (voltage on scantool is average). What can it be? It has me stumped, I cannot figure it out, but most problems point to my harmonic balancer. It'* not really making noise, but it does have alot of cracks in the rubber. So, throw some ideas at me and I'll check them out. Thanks!

IAC solenoid needing cleaned, Throttle body cleaned, Throttle body gasket bad, valve dirt / crud (seafoam treatment)

Not 100% on your year. But the balancer shouldn't be able to create any timing issues if that is what you mean by saying it might be the balancer. The interupter rings on all the balancers I've seen are fastened to the inside of the hub and not the rubberized balancing area of it.

Have you scanned it to ensure the Tachometer isn't off? I know most that i've seen are off 200ish rpm typically.

You know what, now I feel stupid. It just might be off. Because when I shut it off, it stays at 1000, and also at WOT, it shifts at 5500, which I know isn't right. Nonetheless, I still have a unusually rough idle.

Myfirstbonnie, everything has been cleaned when I put the supercharger back on.

Bump, any tips? I'd like to track this down before it gets too cold. It'* still rough nonetheless, and it'* getting kinda annoying. I'd like to get a idle reading on the scantool, but on my year, the RPMs don't show up on the scantool. I did notice in Don'* one video, he has the engine RPMs coming up, would it be ok for me to switch to the '95 year selection to check my idle RPMs?

Darn... switched the scantool to '95 L67, and the engine RPM shows 0. Oh well, I did get some other numbers -

Spark Advance - 24 @ around 1250rpms (idle I have)

ST fuel trim - 128

LT fuel trim - 133

I wish I knew how to check this stuff or had the tools to do it as mine always idles rough also @ about 900 on the tac .... :?


Good luck...

not trying to jack your thread, but is 1000 unusually high? Mine idles at 1000 but it'* not rough.

i think your tach is probably off, even tho you cant figure it out...my '88 idled at 1000-1100 at the tach but realistically it was like 800 rpms. and same with my grandpa'* bonneville and alot of cars of the era that ive seen

UPDATE -

It'* getting rougher. I let my Dad drive it today, and he made a note that it feels like the brake pedal is sinking when sitting at a light/stop sign. I never really noticed it, but it DOES feel like its slowly sinking. I have confirmed that it is in fact idling at 1000, and the tach is not off. I cannot hear any vacuum leaks. I guess it'* just one of those things that are hard to track down. :(