MI6

Brought my car to the shop with idle problems last week, and so far the OBD has come back with no problems whatsoever. Ridiculous, because there certainly is a problem, but which may point to a mechanical/electrical problem. To get to the point, I lucked out because my technician so happens to have a 1988 90 Quattro as well. Because the OBD didn't work out so well (the only thing he found was that there was no "signal" going to the ISV...let me point this out that there was power, but no signal going to the ISV...), so he thought maybe the ECM was dead. So he put my ECM in his car and it worked perfectly, ruling out any problems with the ECM in my car. Put it back in my car, major idle problems. He checked the Tach sensor and said that was ok before he ran out of time, but from here on out he's going on intuition from what he knows about his audi experience with his car since the OBD isn't helping out too much. From what he tells me, since the ECM is fine, it is sensors that are sending the wrong information to the ECM, which in turn is sending a screwball (if any) signal to the ISV. Does anybody have any ideas before I go spend another $400 for him to tinker around with my engine next Wednesday? Your help is SINCERELY appreciated.

Nkugs90

if that is dead it would definitely cause your car to idle rough.

MI6

Brand new factory Audi replacement one month ago