teasdam Posted October 19, 2004 Share Posted October 19, 2004 Why did my stupid car just start idling funny?! It's not so much idling rough, but more loping, low RPM, like it's about to stall causing the whole car to shake. Just watching the engine you can see it rocking/shaking as it idles, but smooths out with gas. Idle RPM (in gear) hangs out around 500, within the range from about 400-600. I've also noticed that when I first start the car, the engine will rev up to about 2000 RPM, then after a few seconds it drops to 1200, then revs back up to 2000, and does this a few times before finally deciding on a cold idle speed...don't know if that's related or not. I've checked the plugs, wires, cap and rotor...the ignition side of things seems to be OK. Timing is right where it should be as well. Then I thought it might be a fuel problem, but the engine runs great any time I give it any gas at all...acceleration and cruising with no problem. IAC is the only thing I can think of that would affect idle performance when the engine runs fine at all other times. I blasted some WD-40 down the top of the IAC to see if that would loosen things up or something, but that had no effect. Also checked all the vacuum lines and blasted them with brake cleaner to clear any blockage. No codes to speak of from the computer, but could this be a sensor problem? What kind of things besides IAC affect idle performance but not driving? Quote Link to comment Share on other sites More sharing options...
MorganM Posted October 19, 2004 Share Posted October 19, 2004 Check (again) for a large vacume leak. Make sure all hoses are free of cracks and are securely pluged in with clamps. Swap out the IAC with another one. Swap out the TPS with another one. Some places to start based off your symtoms descirbed. Quote Link to comment Share on other sites More sharing options...
canajun2eh Posted October 19, 2004 Share Posted October 19, 2004 A vacuum leak can do that. When checking for leaks, don't forget that the purge solenoid valve, stuck open, is also a vacuum leak. This problem won't show up in the computer trouble codes. Quote Link to comment Share on other sites More sharing options...
teasdam Posted October 19, 2004 Author Share Posted October 19, 2004 hmmmm.... so where is the purge solenoid? and how can I tell if it's stuck open? Quote Link to comment Share on other sites More sharing options...
canajun2eh Posted October 19, 2004 Share Posted October 19, 2004 It's bolted to the top of the intake manifold, on the right side. Follow the hoses from the charcoal canister. One of them will lead to a cube that has a second hose going to the intake manifold. There's also an electrical connection. Make sure that the hoses are properly installed and are flexible. Sometimes the heat in the engine compartment will "cure" the rubber and make the hoses stiff and brittle. Sometimes, also, the plastic of the valve body will get brittle and the nipples that the hoses push onto break. If that happens, you have to replace the valve. To check for a stuck-open purge solenoid, blow air through the hose from the charcoal canister while the engine is off. If you can blow air through, the valve is stuck open. Quote Link to comment Share on other sites More sharing options...
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