Predictable engine dying...cause?

[aero]

I'm having an issue with my car dying around idle speed. When I first start it up it sits at around 800rpm and revs itself oddly, just up down up down with small variations in timing.

After driving for a minute or 2, when I slow down to idle speed the rpms just keep dropping and the engine dies. Sometimes it will get to the very brink of dying and then kick back on.

If I hit the throttle at all, I don't have this problem. I've taken to just putting it in neutral and holding the gas and brake at the same time to try and keep the speed up...it's embarassing when you're at an intersection and have to restart the car 3 times in a row.

Anyone know whats causing that? I don't know if I'm explaining the problem very well. My first instinct was the oxygen sensor but I'm not sure.

Any help is appreciated...

87' 325e by the way.

[jlevie]

Could be any or a combination of; intake leak, ICV, AFM, plugs, ignition wires, or misadjusted valves. Misadjusted valves by themselves just result in a rough idle, but if any other faults are present they can push it over the edge.

[aero]

so you dont think it would be the oxygen sensor?

this really happened almost overnight....previously it would do it once every 2 weeks, now i cant go to the corner store without restarting 4 times.

any quick way to check the things you mentioned?

[ivo316]

O2 sensor does not do that even if it fails totally, you may run lean or rich, but if it fails (it did on my Daewoo) it runs pretty normal.

[92 mtechnic cabrio]

It would not be O2 sensor.

Does your car drive normally when you are on throttle? If so, the problem is obviously idle related.

ICV, TPS, or vacumn leak

[kowalski]

don't forget your crank sensor as well. but first
check if you have spark on all cylinders. also clean your ICV and MAF. check all your hoses to make sure they're not cracked and leaking. then start replacing stuff once you'v checked all the cheap and easy things. Then check your resistance on the sensors.

[cobraken]

Try your idle control moduel OR idle control valve. My idle control module shits about once a year.