My 3.1 Olds emits a black cloud of smoke out of the exhaust randomly while driving. Let off and it clears up for a while but it returns. Floor it and it gets much worse.I had the fuel pressure regulator tested with a gauge connected to the fuel rail while running and revving.
It showed steady pressure. We checked the computer under history codes and found only 1 - the O2 sensor. After making some inquiries the consensus was not the O2 sensor. We cleaned the intake plenum while running it (man was it dirty) and there was no change.
I'm gonna change the plugs this weekend and see if there is any difference. I soaked all around the intake and plug wires with water ( to check for an intake leak or bad wires) while it was running and it never noticed or coughed.
Anyone out there have any ideas as to what this could be?
Stumped! Maybe a throttle position sensor?
How do you test it without replacing it?
What now?