My ap1 s2k (70xxx miles) is running rich, indicated by the buildup of carbon on the exhaust tips, not the tailpipe. The tips are pretty much covered in black carbon. No engine light so, either it is only running rich slightly (within honda parameters) or a sensor is not functioning (not likely considering there are several different sensors that would detect rich running conditions). Any ideas to make the car run less rich or an actual procedure that will set the original specs on mixing the fuel?

-thanks

 

Check your plugs and plug gap. Your O2 sensor is pretty much the only item that will continue to trim fuel and monitor it all the time. If you have a staright thru exhaust, carbon will be there reagardless due to the nature of the straight thru design. Start with plugs and plug gap.

 

How high do you rev it? s2k's run notoriously rich at high rpm's.

 

Assuming there's no issues, your best option is to get tuned & switch to a baffled muffler. With an open exhaust you'll still build carbon regardless of your tune (race fuel & ethanol excluded obviously).

As a precaution, along with checking the O2 & sparks, be sure your catalytic converter isn't toast.