2002 buick century 3.1 with code 0p300

02-07-2012, 06:24 PM
My 2002 Buick Century 3.1 with 150000 miles and code 0p300 (random missfire) stumbles some when slowly pressing the accelerator. I changed the plugs (which were badly burned). The problem was there before and after I changed plugs. The wires were last changed at 75000 miles. The last major tuneup I had done was at about 50000 miles, including a changed converter. The engine idles smoothly and accelerates correctly except at low speeds with part throttle. I read the code and it seems many things can cause this problem. I'm hoping someone can help me narrow this list of possibilitys down some. Thanks for any help, 831johnc

02-07-2012, 06:41 PM
Change the wires again with new ones. If the plugs were that bad then there is a good possibility that the wires are bad too. The other possible issue could be bad coils. Start with the wires and then if the problem continues the coils would be next. I would also suggest a new fuel filter and some injector cleaner.

02-08-2012, 09:17 PM
Thanks GTP Dad. I'll just go ahead and change the wires when I check the sensor you suggested. 831johnc

I went ahead and changed the plug wires. This cleared the code and the car now runs fine. Thank you

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