Rotary Titus

I was parking my car in the garage today when I shifted into neutral, let go of the clutch and pulled the hand brake. But when I was about to turn the car off, I heard it surging and then quieting down, and it kept on going from 700rpm to 2000rpm and then back down and back up. I was going like WTH?? and I pressed on the clutch pedal and as soon as I did, it idled back down to 700 rpm. But when I let the clutch go again, it did the surging again! So I jabbed the clutch up and down for a bit and then after a few jabs the surging stopped when I let go of the clutch.
What do you guys think the diagnosis is? Is the clutch not like aligned so it doesn't completely disengages when clutch is released? Or does this mean my clutch about to bite the dust???? thanks for any input, I might bring it in for a service if this happens again tm morning

bigblockbeater

the best advise i could tell you, if it does it again, its under warranty!

Rotary Titus

thanks, but I just hate bringing it in for them and they'll probably keep it for a while if there is some clutch problems covered under warrenty

Sociopath

Hrmm, doesn't sound like a clutch problem, since your engine surge happened when you're idling. How many miles do you have on your car?

KKMmaniac

I had the same weird idle thing last winter a couple times when starting the car cold, in extremely cold (below -10 F) temperatures. Pushing in the clutch would stop it from oscillating. (and after about 5 minutes of idle up and down and puffing smoke rings, the idle stabilized)

I thought it had something to do with the electronic throttle sensing drag from the transmission internals and the cold, thick tranny lube, and confusing itself trying to compensate for it.

It sounds like another PCM programming "intricacy", and not a clutch problem. I too have little faith in The Dealer to solve such a problem, unless a later PCM flash has a fix for this. (or do you have the latest flash?)

I guess, wait and see if the engine does this again; it doesn't sound too serious. (I didn't like my dry-ice cold engine zinging up to 3200 RPM immediately though!)

samsonite1

check your floor mat pushing up on the gas pedal

Rotary Titus

I have 29,000kms or about 20,000miles on it right now but yea like KKMmaniac says it stops surging when I press on the clutch!
And yea I have the latest flash (had it done like a month ago), but I never had this problem before.
Could it be that the clutch hose or something is loose and that it's not completely disengaging the clutch when the transmission is cold and causing the drag? Could they "tighten" the clutch? Do they do that at each service? Because I remember each time I bring my car home from service I would notice a slightly different clutch effort and even my shift gates seems a little bit different (or is this just placebo?)?
Yea I checked but I don't think it's my floormat, though I plan to put back the thicker winter mats soon..

SilverStreak

One suggestion from my experience with my wife's Miata. There is a clutch switch on the Miata (at the top of the clutch lever inside the cabin) that links to the ECM, tells the computer to adjust idle when the clutch is engaged/disengaged. Her Miata was cycling RPMs up and down, drove me crazy until I found out about this $14.00 switch that went bad. Haven't looked at my 8 clutch pedal, but this may be a simple fix under warranty. Good luck.

Rotary Titus

Thanks, I'm sitting at the dealership right now, I'll see how it goes, if it comes back I'll try out your fix SilverStreak!

Rotary Titus

ok so they just did a test run around the block and couldn't notice the same problem.....
I guess I'll just have to cross my finger it doesn't come back again

Slims8

This is better than listening to a football game on the radio... Play by Play Action!

Rotary Titus

"AND the Rotary Titus tries to go for a slam dunk engine/tranny warrenty replacement... BUT... HE GETS SHUT DOWN BY THE MAZDA TECH WITH THE CLASSIC BLAME IT ON THE ROTARY UNIQUNESS MOVE!!! OOOH... that's gonna leave a mark until the next game... I mean... service.."

LOL :p

SilverStreak

Sorry they couldn't reproduce the problem... isn't it always that way? There is a clutch switch on the RX-8 that sends a signal to the PCM module. It was the source of my wife's Miata idle cycling up and down. One quick way to check that clutch switch is to pump the switch (or clutch pedal) if it settles the idle, it may just be an intermittent problem that the switch isn't always making contact. The switch is a sealed unit, can't take it apart to clean or check.

If the switch is entirely bad (as in our Miata) the only solution was to order the new part and replace it to see if it takes care of the problem. I figured it was a $14 part so it was worth checking the cheap stuff first. It was simple to remove, one plug and one bolt. I found out about the switch on Miatanet. If the problem happens again for you it may be worth investigating.