View Full Version : Weird idle issue and running on half the cylinders...

05-03-2010, 04:35 PM
I just another 89 SC which has about 86k miles on the clock. It runs well, however, it does have a problem or two.

First, on my maiden voyage to work this morning, I was going up a small hill and mashed the throttle down a bit to get the AOD to downshift. Once downshifted, I floored it and the boost cam up to about 8 or 9psi. When it boosted, then engine seemed to stutter and power fall off, then when I let off the gas, it acted like it was running on half its cylinders. So, I nursed it the rest of the way to work. I pull in the parking lot at work, shut the engine off and crank it back up. What do you know, smooth as ice!! ~~~!! I shut it off and back on several times, same result...smooth!

The other issue, and I think I know what this is, is with the IAC. It is only a couple years old, purchased from advance auto. The car will idle ok, but when you start it, when cold, the idle jumps up like it is supposed to, but comes back down way too quick and idle dips down below normal kinda like it is wandering and can't find the correct idle. After the engine warms up, and like I drive to work, it is fine when I come to a stop. If I shut the engine off, then start it right back up, the idle will start to come up, then on its way back down to normal idle, it will suddenly drop to normal, not a smooth transition at all. Do you think the IAC is bad or needs cleaning/lube?

thanks for all the input in advance!!


Tim Groth
05-03-2010, 11:35 PM
With what you've described I would start with plugs and wires. I've had several of these cars run smooth at idol without a miss, then driving and getting into boost fall on its face.

This might have some influence on your bad idol also, but I would tend to agree with the IAC being either bad or out of adjustment based on what you describe.