i have a 1997 pontiac grand am gt 2.4 it was running horrible like it was only hitting on 2 cylinders and threw a p0300 and i figured it would be a coil since that would cause only 2 cylinders to hit... changed the coils and plugs and now it cranks but wont start and its shooting gas and/or exhaust from the throttle body. ive read that the power from new coils could cause a worn timing belt to slip but wasnt quick to believe it. i beleive its only unburned fuel coming from the throttle body. im not that good with a voltmeter so i dont know if i could do those diagnostics myself

Asked by Oct 19, 2013 at 11:18 AM

Question type: Maintenance & Repair

replaced cam housing gasket a while back and had to redo the timing. the car has 207000 miles but maintenance has been kept up

1 Answer


A code P0300 is random/multi cylinder misfire. If raw fuel is spurting out the throttle body I suspect a valve timing issue or stuck open intake valve. Double check the spark plug wires for proper connections to the proper coil pack towers. If that's ok run a compression test. If all cylinders are low it's jumped timing. If one cylinder is low you've got a stuck valve on that cylinder. HTH. -Jim

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