Rough Idle No Stalling



I have a 2001 Toyota celica GT auto. It has 120k miles. I seem to have an issue that really is not causing a problem except for annoyance. After coming to a stop the car seems to exhibit the signs of stalling (car idles rough, shakes a bit) however the car never stalls. Once I start driving all is well. Now I took it to the dealer and they replaced the Idle Air Control Valve which is under the throttle body. They said it was getting stuck and due to the higher mileage possible. It was replaced and the problem is still there. The funny thing is even though the car exhibits these stalling symptoms the idle does not drop below 500 rpm (both dealer and I have verified this). Anyone have any suggestions? Thanks.


Unfortunately it sounds like they replaced the IAC valve on a guess. Is the check engine light on? If so it means that there are error codes stored in the computer. The dealer would have read these codes - or many auto parts stores will read them for free. They look like “P1234.” So if relevant, get the codes and post them.

Other than that the first thing to look for would be a vacuum leak. There are various ways of doing that and most any decent mechanic can check it out. You don’t need to take the car to a dealer. Just find a reputable, local, independent shop.

It is also important to make sure that all of your basic maintenance is up to date - spark plugs, wires, filters at the very least.


Thanks for the response. No, the check engine light is not on. I have run a diagnostic on the car and there are no current or pending codes. The maintenance is also up to date, spark plugs are good (another 20K - 30K left on them), no wires it is direct fire, and just changed the air filter and cleaned the MAF sensor. However the idea of a vacuum leak sounds interesting so I will look into that.


If it only happens while the brakes are depressed look at a vacuum leak on the line to the master cylinder.