I noticed that sometimes when I start the car, it idles at about 750-800rpms. Other times though it is closer to 1100-1200rpms. Haven't found any predictable factor, like weather or temp. Any ideas?

Erik

 

>>I noticed that sometimes when I start the car, it idles at about 750-800rpms. Other times though it is closer to 1100-1200rpms. Haven't found any predictable factor, like weather or temp. Any ideas?
>>
>>Erik

My Nov '02 build Cooper had a "fluctuating idel" that may be what you are seeing. At start up it would move up and down within the ranges that you are experiencing. An ECU upgrade seems to have taken care of the problem.

 

another factor is the A/C being on!
it will idle higher with it on!

 

>>another factor is the A/C being on!
>>it will idle higher with it on!

Good call! I'll have to pay attention to that and see if that's whats causing it.

The idle doesnt fluxuate, its either stays in the 750-800 range, or its in the 1100-1200 range and is consistant...so I don't think it would be the ECU like edlfrey mentioned.

Thanks,
Erik

 

my March '03 build MCS has "normal" idle I'd say, it's about 1k RPM during warmup, and about 700 RPM when it's warm. No weirdness, and always predictable.

You may have a sensor gone bad, and be mindfull of your accessories, and also perhaps a fresh ECU update is in order.
Good luck!
Cheers,
Ryan