Near Stall at Idle, "Revving" While Driving

[mkuehn]

Last week, my car began to idle really low while cold, almost to the point of stalling. Once I got out on the freeway and the engine had warmed up, this didn't happen any longer, and it would idle normally while I was stopped in traffic. Then, after it had been parked at work all day, the same thing happened on the way home. Again the next morning, I almost stalled at a couple of stoplights, and this time, the check engine light came on. But again, after it had warmed up, it was fine. So the next morning, when I started the car up, the check engine light went off, just as I was leaving to take the car to the mechanic, and instead of almost stalling at idle, the car instead revved while driving, bouncing between about 1000 and 2000 RPM. When I got to the shop, of course, it was running normally, and since the check engine light wasn't on either, they couldn't read any current or history codes, and said there was nothing they could do unless I could bring the car in again when it was exhibiting these symptoms.

Now I don't really want to drive the car back and forth to work in this condition, but unless I luck out, I'll never get to the shop at the exact time my car is acting up.

Any ideas from anyone? Is there something simple I can try myself to fix this? I don't have a lot of tools or repair experience, but if there are some cheap possible solutions, I'm willing to try them. I thought maybe I had a bad tank of gas, but I filled it again last week, and that didn't seem to change anything.

The last repair on the car, in March, they had to put a helicoil in one of the spark plug ports, and they told me to "keep an eye on it" whatever that means. I don't know if that's at all related or not; I'm just putting it out there.

Thanks for any pointers.

My current solution is to keep driving and see how it goes, since I don't really have any other options, short of trading it in for a newer car, which is a real possibility, if this is a sign of things to come.

123K miles

 

[concept]

I had a strange problem with my MX6 GT, a couple of years ago. No one could figure it out. I took the car to a dealership that employed a mechanic with over 20 years of experience with Mazdas and he told me that in order for him to "catch" the intermittent problem, he would have to keep the car for a couple of days. This is especially critical if the problem occurs when the engine is cold.

So I left the car there for two days and sure enough, he was able to nail the problem down. It was a bad distributor - something I never would've guessed.

The moral of this story? You should leave the car at a shop or dealership that employs a seasoned Mazda mechanic or maybe even just a seasoned mechanic.

Good luck.