For those of you who like diagnosing strange problems I have a doozy for you.
The symptoms are as follows: Very rich smelling exhaust, inside of tailpipe VERY thickly coated with soot, badly carboned plugs.
I have checked the following: Manifold vacuum (20 ish in/Hg at idle in gear), done an aceytelene test around the intake and throttle-body gaskets/assemblys. The OBD system reports NO PROBLEMS, the mpg figures are all over the map over the past 2 months I have gotten from 14 to
33! mpg using the same brand/grade of fuel driving the same routes every week. I have made NO changes to the vehicle WHAT SO EVER.
This has me stumped.
How about you.