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Code P0300 - Random misfire

08-01-2008, 05:59 PM
Hello everyone. When I got my 00 GTP it had the SES light lit and would stumble under acceleration. It would also occasionally stall. The SES light was the MAF voltage. I got a used MAF sensor from the local junkyard. The idle and stalling are completely fixed now. The car still stumbles though when pushed. The code it throws now is P0300-Random misfire. I figure a good tune up is the next step and am looking for opinions on what type of plugs and wires. Money is very tight right now (got a baby boy coming!) so keep that in mind.

Thanks all

08-01-2008, 08:15 PM
The first place to start are plugs and wires. A bad plug or a bad wire can cause the random misfires. If you had a misfire on one or two cylinders the issue could be a coil but at this point start with the above. If that doesn't eliminate the problem then you may need new coils or a new ignition module. That is where you can go through some money very rapidly so I hope the plugs and wires fix the problem. You may also want to change the PCV valve too. Only costs a couple of dollars and don't forget the fuel filter. Fuel starvation can cause the same issues. Good Luck and let us know how it works out.

08-02-2008, 01:26 AM
I'd rent a fuel pressure guage and check fuel pressure first.

Stick with ac delco plugs and wires. for all 6 plugs and the delco wire set, the total shouldnt be any more than 100 bucks.

08-02-2008, 04:43 PM
Respectfully, have you ever seen a bad PCV valve? I never have.

If the OEM spark plug wire "organizers" are pillaged or not used, it is fairly easy for a wire to start to chafe a little and then develop a "short" which can arc energy to ground. I put that "short" in quotes because it's kind of an "electrical leak" which doesn't force the energy to jump the gap to ground....instead it takes a path of lesser resistance.

08-02-2008, 10:39 PM
I think plugs and wires are probably a good place to start, but if a wire were bad, woundn't he see a PO302 for a single cylinder instead of a PO300? Which is why I tend to lean more towards fuel or air delivery problems.

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