tornado_735 Posted March 2, 2010 Report Share Posted March 2, 2010 Things have been going pretty well with the GP lately, other than this one issue. It seems to pop up randomly. At very low RPM, such as when coming up to a stop light, or driving very slowly (such as in a funeral procession, or through a school zone) the engine tends to surge. The RPM will drop very low, then pick up on it's own. Some times, it will cycle like this a couple of times, and will just stall. It drops so low that when the RPM comes back up, it will sort of thump against the transmission, kind of like the same feeling as dropping it into gear with your foot on the gas. At WOT it runs great, on the highway, it runs great. I almost want to say it acts like some sort of vacuum leak, but to say it's that doesn't entirely make sense to me since the problem is erratic, and can happen 3 or 4 times over a span of a couple of days, or can go a month without showing up. Sometimes when I have to drive very slowly, such as in heavy traffic, I will keep it in second gear to keep the RPM up. Then it acts fine. I have no SES light, and no other drivability issues that I know of. Any ideas? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 2, 2010 Report Share Posted March 2, 2010 Maybe a sticking IAC? Usually, vacuum leaks manifest themselves by high RPM, you have exactly the opposite. Had a similar issue with my LeBaron a few years ago. Took the IAC off, cleaned it thoroughly with throttle body cleaner, and haven't had a problem since. I'm not saying it's the ONLY possible cause, but something to think about. Quote Link to comment Share on other sites More sharing options...
1990lumina Posted March 2, 2010 Report Share Posted March 2, 2010 The IAC on my Lumina took a shit one night and resulted in either 2200rpm idle, or 300rpm idle.. no in between. Quote Link to comment Share on other sites More sharing options...
Regal_GS_1989 Posted March 2, 2010 Report Share Posted March 2, 2010 x2 on the IAC. My cutlass used to randomly stall, and cleaning the IAC eliminated 99% of the issues I was having. The idle would still occasionally be sporadic, but no where near what it originally was. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted March 2, 2010 Author Report Share Posted March 2, 2010 I will give that a shot, and see what that does. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 2, 2010 Report Share Posted March 2, 2010 One thing to keep in mind...keep the pintle pointed down while you're spraying the IAC. It will keep an excess of solvent from finding it's way deep into the guts of the solenoid...seen a few accidently killed this way. I will give that a shot, and see what that does. Quote Link to comment Share on other sites More sharing options...
tornado_735 Posted March 3, 2010 Author Report Share Posted March 3, 2010 I was thinking that i could just replace the iac but they are like $50 so i think i will just take my chances with cleaning it. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted March 3, 2010 Report Share Posted March 3, 2010 Be sure to clean out the housing the IAC fits into as well...I usually use rags, and a few q-tips, the ones with the plastic sticks. The paper ones usually fall apart the moment the solvent hits them. Quote Link to comment Share on other sites More sharing options...
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