Hey guys,

When I start up my TJ Sports in the morning it is sitting on around 1800RPM. It will then drop to around 1100RPM (not my normal 800RPM idle) after around 10 seconds, but once i reverse out of the driveway and put the clutch back in to change into first it will go back up to 1800 again, and drop back to 1100 if i leave the clutch in for a while. For the first km or two of driving it will continue to hit 1500-1600 whenever I put the clutch in, then settle back to the customary 800RPM idle speed. Any idea what this could be? I'm going to give the throttle body a clean tomorrow and see if that helps, I also have a spare TPS laying around somewhere.

Cheers, Tim.
P.S - I have done a search, but as the search function isn't fully functioning at the moment due to the forum upgrade (or because there isn't a thread covering this), I haven't found anything helpful.

Uuummmmm. Every car I've owned has done this on start-up, it gets more obvious as it gets colder. Have you had the car long?

Unless I'm reading this wrong it sounds completely normal.

I've had the car for a year now, for the first 9 months i'd start it up, it'd rev to 1800, drop back to 800-1100 idle over a few seconds and then settle out at around 800 idle after a few seconds and then would stay at 800 idle. But now it drops back to 1100 idle, and then rises back up to 1800 idle after reversing back out of the driveway or even just revving it for a few seconds.

I've started a similar thread before and the consensus from everyone was, "expected" / "they all do it" .. some kind of anti-stall measure I guess.

There is a wax pellet in the throttle body that when cold allows more air passed closed butterfly via a chamber, and as the coolant flowing past it heats up it closes, letting it drop to normal idle setting. Its normal, but if it is worrying you then you could get TPS, checked out. The throttle body clean is always a good thing!