1999 Honda Prelude Black Exhaust Smoke

Suggested Repair

Black exhaust smoke indicates a rich mixture. Inspect the spark plugs, then check base ignition timing with a timing light after disabling the computer as required. Correct timing if it is off. Timing adjustment is not guaranteed to fix the smoke or poor mileage.

Conversation Summary

A 1999 Honda Prelude SH has black exhaust smoke and reduced fuel mileage. The owner was told it could be the throttle body, computer, or piston rings. The expert explained black smoke means too much fuel, white is water, and bluish is oil, and recommended checking the plugs and ignition timing. The plugs were black on the rim with a reddish-brown tip. The expert said a timing light is needed and the computer must be disabled to set base timing, but correcting timing may not fix the problem. Any ordinary timing light from a parts store is sufficient.