I don't drive my rx8 in the winter but I do start it up and let it warm up in the garage about once a week. Due to the relatively extreme winter temperatures here in Indiana I've been starting it up every day and letting it warm up along side my winter car before I go to school/work. The last couple of times I've started it up the car has started and idled fine, right up to the point where I take my foot off the clutch. If I release the clutch the engine will begin to continuously climb the revs to about 3500-4k and suddenly drop back into the 1-2k normal warm up range. This will continue until the temp gauge gets half way to normal operating temp. Just wondering if this is normal rotary behavior when the temperature is -10 F, or is something broken and about to explode? No check engine lights or misfires but exhaust smells richer than it has in the past.

2004 manual trans Rx8 GT
-BHR ignition upgrade
-Re-Medy water pump upgrade
-Agency power catback exhaust
(oil metering pump failed/was replaced within last 500 miles)

 

For that cold of temps its normal

 

Normal. The ECU has alternate idling profiles for really cold temps.

 

I was not aware of that, thank you!

 

I agree with with above suggestions, also, avoid leaving your car in gear overnight.. I had this happened twice, I started my car in -40 while in gear, after starting, I shift to neutral and released the clutch the revs started dancing arround from 1-4k back and forth. So Leave your in neutral and yes the first few seconds the rev may stay arround 2.5k but will come down.

I hope this helps.

 

Mine did the rev from 1-4k for like 5 min when it was reaaaaaaally cold. Why do you think it only does that when it's left in gear?