Cold Start Auto Reving
 

:newbie:

The Problem: During very cold startups (listed below) the car starts really slow, has to crank for up to 10 seconds before firing up. Then it revs itself to a constant speed to between 3K and 4K (depending on how cold it is) while I’m depressing the clutch. I make sure it’s in neutral and let the clutch out and the rpms drop 1K and it starts revving itself between 3K and 4K very quickly. As it slowly warms up it always revs 1K at a time but slowly lowers until its revving between 1.5K and 2.5K and then it stops revving itself and levels off at 2K and holds there and as it warms up the revs slowly come down to the normal idle speed. It started when it was this cold but seems to be happening now even as it gets a little warmer (like zero, HEAT WAVE!) Is it really that normal for this car to rev itself? and only rev itself while the clutch is out? When it starts revving itself I depress the clutch and it stops revving and holds a high constant high rev. Just this morning it started revving itself as it usually does but this time as it hit the top of its rev and then as soon as it drops off the peak to come back down it started back firing, not like a serious loud pop snap of a back fire but an obvious pop, just one per rev cycle for about the first 2 or 3 minutes.

The Car: 2004 manual Mazda RX-8 Grand Touring , No mods only Redline oil in the tranny and differential, 33,000 miles, 89 octane fuel, current on all recalls, never been flooded, still under factory warranty.

The Location: Appleton, Wisconsin, USA

The Climate: Freakin COLD!!! -12 Degrees F with a -45 Degrees F wind chill, 74 inches of snow, parked outside occasionally (freakin girlfriend with one car garage)

The Snow Fun: Whoever says to garage an RX-8 for the winter is a fool. Get yourself a good set of snow tires and have fun, toss that rear end out a little around corners. My last front wheel drive car (97 Monte Carlo) sucked in the snow, no traction control, DST, or limited slip differential. My RX-8 is so fun to drive in the snow. Wheels spin TC kicks in and backs it down. Too fast around the corners DST kicks in and somehow no matter how bad you screw up (within reason! DST will not cure stupidity) you always end up pointing the hood in the intended direction. OOPS! going the wrong direction, no need for a Y turn, turn the TC and DST off, downshift, plant gas pedal, steer hard left or right and in about one second poof your pointing in the opposite direction :rofl: .

Zero is still cold man. That warmup must be running super rich, your popping proves it. It's a known design hiccup they fixed with later pcm flashes in the end of 04', before it used to just stall and flood.

Just to test, try switching to 92 octane fuel at a place that has the fuel cleaning addative like Techron/Shells similar for the next 2 gas ups. That should help your startups in the morning, higher octane rating will help engine warmup, since a lower rating will be prone to pre-detonation (fuel burning up completely before rotor cycle) which engine knock is a byproduct. the ECU will automatically retard the ignition timing, but with that cold weather better gas will help the warmups for sure.

I have a little less than half a tank of gas which I should burn off today. Ill fill up with 91 octane for a couple fills and see if theres a difference. Thanks for the suggestion I'll let you know how it turns out. I’m also going to shoot the local dealership an email to see if they will take a look at it.

Thanks

sounds like a quirk caused by a bad neutral position switch... you will get a cel from it after while..

beers :beer: