P0507 CHEVROLET -

Question

My 1998 Che Silerado pickup 5.7 engine idles irratic...It goes up to 1200 to1500 rpm and when you are driing and apply the brake after a few seconds idles normal...Sometimes going down the road the idle goes up to 1500 rpm een at low speeds,,,hold the brake and bring to a stop and in a few seconds the idle returns to normal.. I hae cleaned the egr... replaced the tps and the idle air control sensor motor...It helped but did not fix the crazy idle...Is this a common feature and is there a fix??I don't mind replacing parts if I know the problem...Can you please help......

Answer 1

P0507 Idle control higher than expected. Smell the oil after you warmed up the truck. If it smell like gas then the pressure regulator is leaking,and that inside the intake manifold, you have the famous popet injector, its nickname spider injector sometimes these hoses ruputure .Other than that look for a vacuum leak especially at the intake plenum and the intake manifold itself.use the cleaner you used to clean the EGR,also use it for the MAF (mass air flow) check also the MAP sensor area, By the way if you dont mind replacing part sometimes the IAC is just too old to carry out its duty.