idle problem
 

Hello, my 85 325E is blowing fuse #9 frequently, I have run diagnostics on all related sensors and wiring, installed spare ECU , cleaned out idle valve on engine, and adjusted the TPS. all check fine.
the idle is running about 2500 rpm until I replace the fuse, then back to normal. standing alone at idle it will run for about 4 minutes until the fuse blows, or about 30 sec. if driving. Please help.
Mike

ok, replaced the o2 HEGO relay, seems to have worked. Checked wiring dia. from dealer as Bently doesnt have fuel sys diag.

I was going to post that you should try replacing the relay, but looks like you figured it out before I could post.

Yes, when looking at the diagram from bmw of Ann Arbor, i realized that on ly adirect short / load over 15a could blow the fuse, so checked all direct loads on that circuit. ( elect. 101 ) i believe.

Surging problem now, 2days fine, weather is about 30-40 deg F. I thing something may be overloading a relay?? is this possible?

This sounds weird, but today I unplugged the O2 sensor, no more problem......idle is fine except a little rough from rich condition. possibly a bad replacement sensor? it was bosch 3 wire universal type.
???

I have heard of rare cases where a bad o2 sensor can cause a bad idle...