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Stalling Troubles

Hi all,

I have a 2003 Mazdaspeed Protege that is having a stalling problem. I’ve talked with people on other forums, tried what they suggested, and have had no luck. The motor has about 30k miles on the block with around 3k miles on the internal components (rods, pistons, cams, etc.). Cylinders were bored 20 over and head was machined.

This stalling, or almost stalling, problem occurs when I start the car after it’s been warm for awhile. For example, if I were to drive for an hour, park it for 45 minutes, and then come back out to start it up. It’ll fire up, drop to idle, and then the idle will dip, stalling 50% of the time. The rough idle lasts anywhere from 5 to 20 seconds, and then usually fixes itself. Giving it some gas does nothing to alleviate the problem; sometimes making it worse. Cleaning the idle air control valve solved this for a few days, and then it was back to its old ways. These symptoms do not occur on cold starts or if I restart the car after 5 or 10 minutes of it sitting. We couldn’t find any vacuum leaks and there are no codes being displayed.

Any thoughts?

The first thing that I would do is to check the fuel pump pressure. If that’s within limits then I would replace the idle air control valve with a new one.

Another item to check is the fuel pressure regulator. Remove the vacuum hose and check for fuel/ fuel vapors. There should be none.

@MattsMSP I would replace the idle air control valve. The fact that cleaning it helped for a few days leads me to believe that it’s gummed up.

By the way, why has your engine already been overhauled?
Did you run out of oil or overheat the engine?

Thanks for the advice. I’ll look into this stuff.

@db4690: Short story (sorry). I bought this car as I needed something small/fun and having owned one before with zero problems, I figured I’d try it again. This time, however, the individual who owned it before me must have really beat the crap out of it as when I got it home, I discovered the head had been chewed up and he had spun a rod bearing, among other things. He had the motor replaced under warranty about 30k ago for a spun rod bearing and must have learned nothing from it. I have a feeling the kid cranked the boost up from the turbo without doing any additional tuning. I’ve definitely learned my lesson…