Author Topic: Runs rough when cold until engine is warm. (Read 3671 times)

timc1018 · « **on:** December 18, 2009, 07:33:03 PM »

1991 318is, car starts up cold perfect, and idles perfect, but will not take any gas (engine spits, misfires, backfires in intake and exhaust when I try to give it gas when cold) until engine is warm. Once it's warm, runs perfect. I've replaced all vacum lines, plugs, temp sensor, cam sensor, cleaned throttle body. Have not checked or replaced ICV....

DesktopDave · « **Reply #1 on:** December 18, 2009, 07:48:11 PM »

Check the TPS or the temp sensor in the AFM? I didn't see those in your list. You took all the good answers already! I don't think it's the ICV, doesn't sound right.

timc1018 · « **Reply #2 on:** December 18, 2009, 07:51:40 PM »

Thx Dave, how do I ck these two parts?

I was thinking the problem would be in some part that is sending an incorrect temp reading to the brain, or the ICV not opening, or staying open.

fiftytakedowns · « **Reply #3 on:** December 18, 2009, 08:15:13 PM »

multimeter to the some of the pins in the AFm usually telss if the intake temp is right, I can bust out my graph and let you know the specifications.

I think the ICv has to be buzzing, and mine never buzzed :/

DesktopDave · « **Reply #4 on:** December 18, 2009, 08:18:52 PM »

Yeah, what he said....I don't have the specs, but the pins in the AFM are paired from the flap resistor and a thermisor temp sensor. It should be in the elec troubleshooting manual. It's a long shot, though.

The ICV def buzzes. You can test it with a 9v battery or a 12v jumper. I cut the end off a 9v wall wart to test mine.

richbarn2 · « **Reply #5 on:** December 26, 2009, 11:03:53 AM »

If it turns out you need an AFM, PM me. I picked up a spare.