Strange random vibration at idle
Just purchased a 1993 318is as a weekend car. It is an automatic, about 200,000 mile.
Anyways, everything works great on the car (for 200,000 it has some personality traits) but my mechanic inspected it and it gets the ok.
However, I noticed something new yesterday.
The engine is strong and idles wonderfully. However, sometimes when I stop and an idling in drive, a random vibration and loss of power will come over the car. It only happens when in idle.
It almost sounds like something is blocking the exhaust. I don't think it is a fuel pump, since I had those problems before and it doesn't seem like it.
This one is completely random. It will last for 3-4 seconds and then disappear, only to reappear later.
I tried to diagnose a pattern of when it happens, and can't pinpoint one single factor.
It will be maybe 6-10 pretty good vibrations, the tach will go down a bit, and then it will be fine.