1994 Mazda Protege



January, 21, 2013 AT 7:41 PM

So I am at work right now and on my lunch break I went out to grab a smoke and sit in my car with the heat on. As soon as my engine started up, the RPMs started going crazy. My car revved up to over 2000 RPMs and was attempting to go higher. I turned it off completely and started it up again, this time it went to 2000 RPMs and was looping? Where it would go up and down around the 2000 RPM range up to about 2300 RPMs. I turned it off and tried again, this time like the first it just held at high RPMs. When I pressed the gas once, the RPMs went up as expected and attempted to maintain that RPM, about 2300.

Switching to any gear other than park sent the RPMs to a normal level around 1000 RPMs and under. However, when switched back to park from another gear, such as Drive, the engine starts revving up again to around 2000 RPMs

I am worried about driving home now after work, as an engine revving itself up scares me the death. This is the first time this has happened to me and I was wondering what may be causing this, and if I should drive home or have my car towed?

If it helps any, my car is an automatic transmission with a rebuilt transmission in it (placed in last year). I also recently had the rear O2 sensor replaced, as it was causing me problems as well. The transmission has already been having problems with getting into first gear, it does that very rough and jerks a bit nearly every time, though most of the other gears shift pretty smooth. I tried taking it to the shop that rebuilt the transmission and they wouldn't repair what was wrong with it without me paying full price, which I can't afford. I was told the transmission cable was slightly loose and that some of the "connectors"? Were slightly misaligned.


3 Answers



January, 21, 2013 AT 7:52 PM

It sounds like a faulty IAC or idle control motor, I would be wary of driving as it may act up when you start to slow down at lights and leap off into the car in front, I would get it towed and looked at asap.



January, 21, 2013 AT 11:47 PM

Thanks so much, I did make it home fine and it didn't rev up while driving at all thankfully. I'll get the IAC checked out first.



January, 29, 2013 AT 3:27 AM

It turns out I was 2 quarts low on coolant. That and letting the engine warm up first to normal operating temperature has made it drive totally fine. It still revs up a bit in park when its cold out but now it stabilizes out in about 5 minutes. If I have any more issues idling the IAC will be my first check! Thanks again.

Please login or register to post a reply.

Vacuum Leak Test and Repair - All Cars
Code Read Retrieval/Clear Honda Civic
Read Codes Like a Pro
Code Read Retrieval/Clear Mercedes Benz
Code Read Retrieval/Clear