What Would Cause High HC 1992 Cadillac

I just purchased a 92 Cadillac and while I passed the smog check the HC both on the low test and the high test were almost at the limit. The smog tech thought that the car might need a new set of plugs wires cap and rotor, but in looking through the service records this was all done about 6,000 miles ago and they used OEM parts. what other areas should I check? the records indicate that all of the previous emission testing has passed with flying colors and I would like to maintain the car in a top running form.

Answer:

You do not mention your Cadillac's CO results so we'll assume they are low... perhaps even 0.00, leading you to believe your Cadillac does not have CO problems.

If this is the case you'll need to check your Cadillac fuel feedback system. Low CO (lean fuel condition) would cause high HC as well. Things to check for would be vacuum leaks, dirty fuel filter, possible faulty MAF (Mass Air Flow) sensor, dirty fuel injectors, and the like. Basically faults which would cause less fuel than needed fuel entering the combustion chambers, or faults which would allow "unmetered" air to enter the combustion chambers. Unmetered air would be any air source (leak) after the MAF.

Follow this link for What Causes High HC Faults.

posted by SmogTips Support