Lately, all of a sudden, I have noticed my car running rich, very rich. The bumper on the driver's side gets a black mark every day now after 60 miles of driving (true duals with crossover would send the exhaust from cylinder 6 to the driver's side, correct?). I decided to change the spark plugs out. All the plugs looked fine except for cylinder 6 which was completely gunked up and was causing a hesitation under loaded (not firing I assume). I replaced all of them for giggles, and came to find that only two weeks later, cylinder 6 was yet again gunked up like before, even with the brand new spark plug. I am using AC Delco R44T's. I ran these for a year previous to this with no problems. What's going on in cylinder 6? Is this the reason the car has decided to run rich all of a sudden? Thanks.

 

is it a fuel injected car? If so test the injector.... Are you sure its even firing on that cyl. at all? Check for spark.

 

Good idea, I never even thought to check for spark, haha... Will do that tonight and get back to you.

Carb'd, Edelbrock 1406, 600CFM.

 

All cylinders have spark.

 

ok, you could do a compression test to try and determin a bad piston ring (does it smoke all the time or just on start-up) As long as all the cylinders are within about 10 percent of each other its most likely not a ring.

Really sounds like a valve seal though. Start it up and see what color the smoke is and if it only smokes on start-up or all the time.

What do you mean the plugs are gunked up. Is it globs of black carbon or what. Is it wet with oil or gas???

 

Looks like black, wet rtv (same consistency). A small dab of it on the end of the plug between the head and contact. It's wet and oily. It releases a pretty good cloud of smoke at startup, smells like rich gas and is mostly white. My friend has told me that under heavy acceleration between shifts he sees some white smoke come out as well. The engine is coming out in a few weeks time and being replaced, so I'm not too worried about it, however I don't want to keep replacing sparkplugs to keep it running well. I'll see what I can do about a compression test. Thanks for your help, I'll report back.

 

good luck man....really sounds like a valve seal went though.