So ever since I got my mini it gets a little strang at start up. If i haven't driven all day (so first start up for the day) the engine seems to go up and down from 600-1000 rpm as if i was rapidly pressing and depressing the throttle. It doesnt happen for long, but it does happen. I was wondering if this is just what happenes because the engine is not hot? Does anyone else have this happen?

 

Yeah, it's not that weird. Mine does this on cold days especially if i place a big load on it.

 

Mine does it sometimes as well in cooler weather....once she warms up it levels off smoothly.

 

yup mine does the same just let it warm up a bit... It just bad programing on minis part... but guess what you take it to the dealer and they find nothing wrong and magically they can not reproduce the problem... Who would have guessed.

 

Well, I dont think that is a programming error. As far as I know this should not happen with brand new cars. It might if your car has around or more than 50,000mi on it. One reason for this might be a faulty IAC valve(Idle Air Controller). This controls the idle speed of the engine. Unusual revs occur when this doesn't close properly. This doesn't affect the car in anyway but mileage goes down and that up and down becomes irritating some times. Usually the car heats up by the time we get to dealer's. So they can not reproduce the problem. I had this problem on my old Ford Probe. Well there might be other reasons too...

 

yeah the only time i notice it is directly after a cold start. Once i drive away and stop it goes away completety. The only thing that changes as it warms up is it idles at lower rpm (which is good and normal). The throbing rpm at cold start is just a really short thing, i just didnt want it to be something that would be a sign for a problem a couple years down the road.

Thank you

 

Well it could be because the car is too lean, that would explain the lack of power at the first jump of the day.

BTW the dealer had the car for almost a week... and was explained to let the car sit over night before checking it.

 

Mine did the same thing, for a time, then it completely stopped. It hasn't gotten any warmer here in Missouri either. I did notice the weird idle when it first got cold in September, but like I said above it has ceased and the days are much colder now then they were in Sep.

 

Just FYI, my Mazda6 does this as well. I think it may be common on manual cars. It only does this when the engine is cold and it is cold outside.

 

I had a similar idle problem. Mine was not at cold, but engine warm from running errands. The idle would get so bad the engine would cut out. Cutting the car off and taking the key out and restarting it would clear the problem.

 

Is your auto-climate control on? Try shutting it off prior to shutting the engine off the evening before and see if it makes any difference. (just a suggestion - I haven't tried it, but know that compressor cycling is often a reason for idle speed jumping around on certain vehicles).