This morning when I got into my car to go to work I noticed it was idling at 1500 rpm. After a little bit of driving I put my car into Park and Neutral at a set of lights and it seemed to be idling fine (i.e. around 500 rpm). My boss used to be a mechanic so I ran it past him and he suggested that it may be due to the cold as cars do tend to idle a little higher sometimes during cold weather, although he said 1500 rpm was quite unusual. I then got in my car after work to drive home and once again it was idling at 1500 rpm. After waiting about a minute or so the needle then dropped to about 500 rpm and then slowly went back up to 1500 rpm. This happened a few times and then it seemed to settle around 500 rpm but still rose to around 700 or 800 rpm every 30 seconds or so. It idles fine when it is in gear (tiptronic) - it only seems to idle funny in Park or Neutral.

Does anyone know what could be causing this as I am concerned it may turn into a bigger problem? If so, does anyone know how I can go about fixing it - I'd like to do it myself if possible? I have not had a chance to look under the bonnet yet as it was too dark when I got home.

It would most likely just be a faulty sensor of some description. Get Mitsubishi to check the ECU for error codes.

Try cleaning your Throttle Position Sensor (TPS) connector with an alcohol solution. (ie - meths) It's the little black doobie screwed to the front side of the throttle body. They build up a nasty green gunk inside the plug over time. Your ECU might be getting bad readings from it.

The Idle Stepper Motor might be stuffed. It controlls the idle speed

Try cleaning your Throttle Position Sensor (TPS) connector with an alcohol solution. (ie - meths) It's the little black doobie screwed to the front side of the throttle body. They build up a nasty green gunk inside the plug over time. Your ECU might be getting bad readings from it.

I'll have to check that out as soon as I get a chance. Hopefully that's all it is... :confused:

Just a quick update - I haven't had any problems such as the one above since the incident. It still idles at a stable 1000 RPM when I start the car but I'm putting that down to the cold weather as it only does it when it is not in gear and only when the car has just been started up. I guess I was just being paranoid as I've never noticed it before. :redface: