Ok ive got an 2001 blazer and it gives me the p0300 code witch is multiple cylinder misfire. Ive changed the spark plugs, wires, distributor cap, rotor,coil, and the the fuel pressure is good no problems the misfire got better but is still there can only feel it when you do like 65 70 or 55 sometimes. Im out of ideas i even pulled all the plugs and wires off twice to see if something wasn't right.

 

*Moving to 2nd Gen Tech* - Gen Chat is for those topics that don't really fit into the other more specific sections.

What brand of parts did you use? These trucks are VERY particular when it comes to ignition components. Many aftermarket brands can have the same problem as the old, worn out parts that you took off to a certain degree.

 

All parts I used are AC delco and plugs were auto light.

 

I too reacently had the same problem and come to find out it was my o2 sensors, replaced them both and shes been fine ever since. This even suprised my dad who is a mechanic with 30+ yrs experience, they didnt throw any codes and i never had any signs of them being the culprate. So id consider them and thier age if they havnt been replaced.

 

so it doesnt show any signs of a missfire at idle? or does it

 

no it used too but after changing plugs and wires it stopped that it only does it at like passing speed now it doesnt even throw a light it just blinks a bit and then turns back off.

 

Blinking SES light indicates a misfire. If it continues, it will damage the catalytic converter. Toss the Autolite plugs or see if the parts store will upgrade to AC Delco 41-993 plugs for you. Those are the correct plugs for your engine, with a gap of .060"

 

sounds like its your o2 i had one go out and if i kicked it or gave it more gas it would almost lay down on me spitting and missing new o2 and everything was cleaned right up maybe thats your problem at whar rpm does the missfire happen if you have an auto trans keep it in first or second and slowly bring it up to the rpm at witch the engings missfire happens if its your o2 it shouldnt matter the speed your traviling but the rpm of the engine test this out and let me know what happens