continued carbon fouling

[Pillarian]

I thought the top maintenance (plugs,wires, gapping valves) would've cured the overly rich running condition, but NOOOOOO.

I pulled #4 plug to check afterward and there was already carbon buildup (only 1,000 miles following). The cars mileage increased about 10%, but not what I was expecting. The CEL came on again (on for a couple of seconds; off; then on again). I probably need to replace the O2 sensors again. They only lasted 10K. I had the codes run some time ago; it showed the O2 sensors as faulty. They were replaced and now I'm back to square one. They're friggin' expensive. Any further suggestions?

 

[Ishodu]

Run them codes again and see whats up. Did you clear the codes last time? Maybe you want to do that then drive for a while and try again.

 

[sdpatt]

How's your engine's oil consumption? The carbon fouling may be due to oil inleakage into the cylinder and the work you described would not have any effect on that.

You have codes so check them. Why are you guessing that it is the O2 sensors? If both sensors were showing the same error then the problem is probably not with the sensors.

If they both show lean then the engine is lean. If rich, well then, it must be rich. Please check the codes and let the Forum know what hard faults and memory codes you find for the KOEO test and the KOER test results.

 

[SHOtimer]

Their have been cases of people using 'cheap' O2 sensors which do no operate very well for very long. The Bosch O2 sensors work very well for these cars and should be used. You should also, inspect for vaccum leaks that the computer is trying to compensate for, and consider replacing the ECT, incorrect signals from this can cause the computer to run the car rich. Also, does the car run cold? A stuck thermostat will cause the motor to run rich longer than what is needed.

Doug