mikeng

This morning I started my car and everything seemed to be going fine. It was around 88 degrees today.
As i drove in traffic with the a/c on, I noticed the car start to hesitate and shake a bit when it hits 500 rpm then it jumps back up to 700-800rpm whenever I stopped at red lights(where it normally idles at). I was scared the car would just die on me in the middle of the road.

Car is at 116K and I've done the timing belt and changed the spark plugs at 105K

There are no codes being thrown by the engine at the moment.

I am wondering if others in the community have experienced this problem, thanks in advance for all your help

Crashmaster

Does it only happen with the A/C on?

mikeng

Yes it does, I forgot to mention that.

MyGuti

its probably got something to do with your radiator fan? cuz I would imagine when your stopped in traffic the fan would turn on....causing the rpms to increase slightly...which is totally normal I believe

csmeance

get the radio codes and navi codes! Undo the negative cable for a few minutes. Turn on the car and let it idle for about 10 minutes (cooling fans need to come on and off 2x). Do not use the A/C, heat, radio, headlights, etc. This will help the ECU relearn the idle. If your battery is on it's way out, it'll cause the ECU to loose idle and cause RPM dips.