Cannock

I have a 86 911 that I think is running rich. You can smell the exhaust well driving and it smells rich. I pulled a couple of plugs and they look gray in color with a little black at the tips. I would expect a brown color if the fuel/air mixture was correct. What is the best way to fix this issue? Replace the O2 sensor? Replace the DME relay?


Thanks for your advice.

Rick Lee

I just had this problem. It turned out I had a leak at my intake manifold on cylinder #5. I replaced the gaskets and then had the mixture reset. I still think it's running rich, so I replaced the O2 sensor. I haven't gotten to drive it enough yet (just did it Sunday) to see if the the new O2 sensor makes a difference.

Steve W

If the O2 sensor is disconnected, or no longer works, a 3.2 Carrera will run very rich, so much so that you will smell it and probably see it. I would try and replace that first, or at least test
the output voltage to verify that it is functioning. If it puts out over 0.8 to 0.9 volts while running rich, then it is working.

Cannock

Thanks for the advice Rick and Steve.

Rick how did you know your intake was leaking?

Rick Lee

I broke down and took my car to a pro wrench and he tracked down the leak. It really crushed me to have to pay someone to work on my car, but $530 on diagnostics and small repairs was well spent before I spend 10x that much dealing with a rebuild or an engine swap.