Cold weather = can't go over 20 mph!

[AV325i]

My 89 325iX has always had problems with reving up and down when I start in cold weather. It also idles high (1200rpm).

However, this week when it got down to 3 degrees, I could start OK, but after the reving stopped, I could not not get it to drive over 20mph until I drove about 3 miles. Then it just kicked in and it was fine.

The engine would start to kill as pressed the gas pedal and then the engine light would come on. When I let up on the gas, the engine light went out and the car ran better, but still only going about 10 mph. I could repeat this over and over again.

Any ideas? Throttle position senosr? Idle control? I have an extra parts car, so I could start swapping things out. Which first?

[TurboJake]

Possibly the AFM flap sticking.

I had this problem last year. When cold, it would stick. It took about 20 minutes of driving for it to warm up and the flap to move freely again, then it was fine.

Check to see if that flap is sticking. The cheap and dirty solution I did for a while was to bring the AFM in with me for the night, and reinstall when going out (Which meant a crappy short filter directly on the end of the AFM, but it worked)

[dnguyen1963]

Possibly the AFM flap sticking.

I had this problem last year. When cold, it would stick. It took about 20 minutes of driving for it to warm up and the flap to move freely again, then it was fine.

Check to see if that flap is sticking. The cheap and dirty solution I did for a while was to bring the AFM in with me for the night, and reinstall when going out (Which meant a crappy short filter directly on the end of the AFM, but it worked)

You can also buy an engine block heater (@ $20 Amazon) and place it near the AFM to keep it warm.