Pontiac Repair: 2001 grand prix 3.1, mass air flow sensor, mass air flow

Question
hello clint here.... I have a 2001 grand prix 3.1 engine misfire... code shows a p300 which is random cylinder misfire.. i have done everything to this car to fix this problem including computer.. coil pack... ignition control... spark plugs... mass air flow sensor... wires...you name it.. it is has been done... it misses mainly when im cruising at speeds around 50 to 70 also on a side note there is a little sensor on the side of the main pulley... that is suppose to work magnetically... i have switched this out but it is still making a spark like an ark of electricity every so often at... and the faster the motor gets the faster the spark gets... but its new and still doing it... can you help pleaseee... im almost to the point of a scrap yard for this thing

Answer
Hi There:

I assue the sensor your refering to in the crank sensor on the harmonic balancer? There shoul be NO soark there. It' an inductive pick up and it is mainly used to smooth out the idle up to about 1500 RPM's above that it's not used.. I would lean possibly toward either a bad injector or a restricted exhaust. you caqn check the resistance of all the injedtor with a digital ohm meter is any one is drastically higher or lower then the other 5 that is the bad injector. check them on a cold engine.. As for the exhaust if you have access to a back pressure tester the exhaust shouldn't have more then 1.25 LBS of back pressure anymer then that the converter is restricted. If you don;t have acces to to one then drop the exhaust at the rear manifold and drive it and see what ahppens keep in mind it may run wierd due to the fact that the manifold O2 sensor is open to the outside air. those are the 2 places I would start looking at. good luck :)