Twice in the past two days has my car randomly stoppe while I was sitting at a red light. Idle is normal, car starts up right away after it stalls (luckily), power remains to the car since the check engine light turns on when it dies. There were no warning signs and it has been completely dry so its not water splashing around. My car has been running at 13V rather than 13.5V lately, but I don't know if that's related. Any sensors to check? This thing had a tune up when I bought it 10K miles ago (about 1.5 years), oil changed consistantly, not overheating, etc. Thanks.

 

Could be an Idle Air Control valve issue.... Might wanna try removing it and cleaning it. Of course it could also be an intermittent hard misfire...hard enough to shut the car off. Or it could be some faulty wiring or a bad ignition switch. My sister's car has a faulty ignition tumbler and it will rock back on its own and shut the car off. Just throwing ideas out there. How's the car run the rest of the time..good? Down on power?

Might check your MAF sensor also....MAF's have been known to cause stalling. You can clean it with some electrical parts cleaner....just dont touch it or anything, just lightly spray the elements down several times and let them dry thoroughly before putting the MAF back in. The electrical parts cleaner dries fast and leaves no residue, and is non-conductive. :lala:

 

Thanks alot. Where can I find more info on the Idle Air Control valve? I'm an electrical engineer, not a mechanic. FOr the record my car has always had a very odd idle. It was always around 600 rpms, then would drop to 400 and catch itself then shoot to 900, then drop back to about 600.

 

my v-6 does the same thing actually . . . sometimes it catches the idle, and occasionally it just dies. The "hard misfire" seems plausible, what might cause that?

 

IAC valve location: follow the air intake hose to the throttle body (where the rubber meets metal) then on the metal part (throttle body), at the top is a big round spark plug looking thing. That is the IAC.

Ah its easier w/ a pic.

 

double post

 

What you guys are talking about is surging...and is usually caused by some kind of sensor problem or a misfire in the engine....

A "hard misfire"...I call it hard because it's not a little burble, it's a severe incident... Most misfires that I've seen are in the ignition system. Check all spark plugs, ensure theyre the proper heat range and theyre gapped properly....make sure your plugwires are in good shape and undamaged. Ohm test them with a multimeter if you have to. Make sure your cap and rotor is in decent shape. Lots of corrosion on the rotor tip and on the terminals can cause poor performance. If that's the case, either buy a new set, or if you're tight on cash, get a file or a wire brush and gently scrape the corrosion off. Just don't go eating at the metal now.....you mess up those tolerances and your car will run crappy. Also the ignition coil being weak is a possibility...they sell ignition coil testers at a lot of auto parts stores. You just pull a spark plug wire off of a plug, connect the tester to it, and have someone crank the motor while you look at the spark. (And make sure the tester is set to your factory spark plug gap.) Blue or white is good. Orange, yellow, red, etc. is weak or unacceptable. You can also do this test with a screwdriver by shoving the end into the plugwire, and holding the shaft close to a fender.....but if youre not careful you can give yourself a nice shock. The tester is more reliable and safer, it's worth the $10 IMO.

 

ok, good. ignition was kinda where i was heading in solving this problem. Some of my plugs/wires seemed a little sketchy, haven't looked at the distributor yet though, damn rain wont stop for long enough.

I'll take a look at those sensors too i guess. thanks.