carlf

My '97 f150 with 4.6 l, 110Kmiles started knocking and backfiring 2 tanks of gass ago. Runs rough, in gear at a stop idles at 400 rpm. light acceleration produces backfire. Hard acceleration gets up and goes with no backfire. added gas treatment to 2 tanks of gas - no help. I removed and cleaned K&N air filter. no help. Gas milage in town is down, but on road is fine (12/17). 90% of miles are in city.

f1fiddys

could be a few things really.. intake gaskets feul pressure regulator or timing of the engine could also be the cause

torkum

Spend the money for a diagnostic scan and then decide if you can fix it yourself. The extra money you spend on gas will be more than getting the diagnoses.