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2002 Monte Carlo SS P0300 Code: Engine Stalls at Wide Open Throttle, Fuel Pressure Normal

Model: 2002 Monte Carlo Fault Code: P0300 Posted: 2011-06-02 07:03

I own a 2002 Monte Carlo SS with a 3.8L V6 and automatic transmission. I'm currently receiving a P0300 random misfire code. When the vehicle is in park, pushing the gas pedal to the floor causes the engine to bog down and only reaches around 3500 RPM—after which RPMs steadily decline as I hold the throttle. Fuel pressure remains consistently at 48 psi under both idle and load conditions with no drop. I've already replaced the spark plugs, ignition wires, coil packs, ignition control module, MAF sensor, and air filter. Despite these repairs, the issue persists. My current suspicions point toward either a faulty crankshaft position sensor or a clogged catalytic converter. Are there any other potential causes or diagnostic steps I should consider? Any advice would be greatly appreciated. Thanks for your help!

Related fault codes
P0300
Comments (4)
Anonymous 2011-06-02 07:12

Could a plugged exhaust system be causing the misfire? This might reduce engine vacuum and affect combustion efficiency.

Anonymous 2011-06-02 07:33

How can I check for exhaust blockage? I’ve tried covering the tailpipe with my hand and feeling for airflow, but I’m not sure if that’s a reliable indicator.

Anonymous 2011-06-02 19:29

go down to your local auto parts store and get a vacum gauge,the read the instructions and hook it up to your car.that is the easiest and cheapest way for a diyer to do it.you could drop the exhaust or drill a 1/2 inch hole before the cat and see if that helps.it's up to you.

Anonymous 2011-06-02 19:56

I suspect the EGR tube may have melted due to overheating, causing a significant vacuum leak. This would lead to over-fueling and poor combustion. The catalytic converter might also be completely clogged as a result of this issue.