fun car guy Posted May 14, 2023 Share Posted May 14, 2023 My '89 coupe starts and runs well but, upon inspection, the plugs are black with carbon and the dash display just says zero MPG and there's no smoke from the exhaust. Is this normal and if not, how do I lean out the mixture? Thanks Link to comment Share on other sites More sharing options...
2seater Posted May 15, 2023 Share Posted May 15, 2023 Are the plugs checked after being driven for a period of time? For fuel/air mixture control the MAF does the gross calculation of the demand, the O2 sensor fine tunes the running system. The only time the exhaust should be readily visible is in cool/cold weather from condensing water vapor. Beyond that, the exhaust should be pretty much invisible. Link to comment Share on other sites More sharing options...
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