Normally I park the car in the garage over night. The other evening though I didn't and it got down to about -15 C overnight. When I started the car up in the morning the revs went to about 3000 and then down to 1000 then to 3000 then to 1000 and so on and so on...every second or so in cycle time. Each time the revs dropped I thought for sure it was going to stall, but it didn't.
When I pressed the clutch in the RPM fluctuations went away. When I let the clutch out the fluctuations came back and so on and so on.
Finally after about 30 seconds of holding the clutch in and then letting it out the RPM's smoothed out to around 1000. No CEL or further issues.
Now I know it's normal for cold drivetrains to impact the idle of motors but not to this degree.
Anyone got any ideas what the heck is going on, it's never done this before.
Very strange.
Railton

 

Replace your tranny fluid with synthetic and those issues should go away.
I'm not sure if there is anything wrong with your engine control but the tranny drag in cold weather is much reduced by the synthetic fluid. Cold weather shifting is much improved as well. (do the diff fluid at the same time)

 

you have a sticky neutral switch..

beers

 

There are quite a few threads on this forum discussing the weird reving issue. This was my first winter with the car (it was parked the other three winters) so I wasn't used to the car acting like that. I did a quick search on the forum and eased any anxieties that I had since it seemed to be a common occurance.

 

I've had to park outside for most of February so I have had this happen on the days in drops to -15 or colder.
Don't worry, the revs will settle down after a few minutes.....the 8 just doesn't like the extreme cold!

 

Normal I think not. It never did this before. I'm taking it in for a look-see.

BTW, FWIW.
I use to use Oakville Mazda for service but no longer. I drove to Oakville Mazda one Saturday for an oil change and as expected they wouldn't take me. So I phoned Burlington Mazda from their customer lounge and they said no problem, bring it over. They changed the oil, replaced two burned out DRL's, gave me a free wash ticket at the Appleby Auto Spa, drove me home and picked me up. I also asked them to order me one of those new dipsticks with the silicone on them for the car so I could read the oil level. They said sure, no problems. I had previously asked Oakville Mazda to order for me three times and they didn't. Burlington Mazda called my office a day later to tell me the dipstick was in and to bring the car in. I said sure and made an appointment for the Saturday where hey changed it and also changed the disk pads on the car since they were squeeking again. All N/C. I received another wash tcket as well at Auto Spa.
No more Oakville Mazda.
Railton

 

Ooo... Is the Auto Spa that giant car wash on Appleby Line by the highway? I've seen it but I've never been. I work on Burloak so I'll definitely have to go try it some time.

I have to say though, I haven't had any bad experience with Oakville Mazda. As I understand it the ownership recently changed and they've been making many improvements. I've had my car in a couple times and both times they washed my car at no charge.

 

Mine has done this as well, at home it is in the garage, unfortunately at work it is outside.
I have started it as cold as -28C and it did this, seems -15 or so or worse (last time -15 it didnt, seems to be -18 or colder now). Took a few minutes to relax a little but mine did pretty much the same as yours.
I feel its normal, one of those 'quirks' that makes the car more interesting..!

 

Maybe the 'stange' behaviour is attributed to any TSB's done after last winter. That'd explain the difference between last year and this year.

Let us know what the shop tells you.

 

I believe it's caused by very heavy transmission oil.. This puts a lot of load on the engine that the ECU is not prepared to handle when the clutch is released.. It gets into a cycle where the RPM's go lower then what the ECU wants so it feed in gas, then it tries to go back to normal cold idle and the RPM's drop too low again. Mine has not done this in a long time so I had though they fixed this in one of the flashes.