forum.audiv8.com Foren English Audi V8 Forum Nothing Much

Just wanted to be the first to post on the english forums.

Looking forward to seeing the english version of the website up and running.

Joe Dawber
1990 3.6 V8

This new board is the first step for the international version of audiv8.com. The translation of the site-layout is done. I'll activate the english version when the bigger articles are translated. The user interface of this forum will also be available in English. Before the login and new user subscription.

Sincerely,
Maik

Hi Joe,
and I want to be the first to start a technical discussion.
I am driving the same model as you, 1990 3.6 V8,with manual gear.
With no problems for years, but now at 130000km my engine seems to
refuse its job. It is shaking and stammering in the full range of revolutions, with
post ignitition at the front part of the exhaust system. Looks like unburned fuel.
Had already checked ignition and injection system as far as you can do it without
error-reading equipment, but found nothing up to now. Did you ever experience
such a failure ?
Greetings from Germany, Manfred

Manfred,
The description of your problem sounds like the O2 sensor has failed. When my 90 3.6 auto failed at 111k miles the fuel mileage dropped in half, the engine shook at all speeds, the idle would fluctuate 400+ rpm, and would vent black smoke from the exhaust. A key clue is that the car feels fine at full throttle. The test is to unplug the sensor and if it runs fine you have found your problem.

Keith
1990 V8q #527

Thats interesting. My V8Q only does about 12-15mpg no matter how carefully I drive it. Also it stinks of fumes when you are stood next to it, and on start-up coughs a load of soot out onto the road. I wonder if my O2 sensor is knackered.
Does the V8 have 2 separate O2 sensors?

The 12-15 mpg certainly fits with the symptoms of a failed O2 sensor. The black smoke on startup does also but usually it will also blow black under medium acceleration. Other symptoms are a "surging" feeling under medium acceleration, and surging unsteady idle. One easy test is to find a lightly travelled road and do a full throttle run. If the car seems to run fine at full throttle then the O2 is probably to blame. Another test is to unplug the O2 sensor from the wiring harness and if the car runs better then the sensor has failed. Of course if you know how you can always check the Motronic fault codes.

The V8 only uses one O2 sensor, dead center in the exhaust crossover on the 3.6 cars, and on the left side of the crossover of the 4.2 cars.

Keith