I'm having problems starting my 2002 pontiac grand prix se 3.1L. I just bought it from a private owner back in Oct. Of 2012. I plugged in a scanner into the OBD-II and got a PO300 reading for mutiple/random cylinder misfire. Initially the problem began when I cleaned the carbon from the intake behind the throttle body because of a previous reading of inefficient EGR flow. After finishing and I tried to start the car again but couldn't without pressing in the gas halfway to start it. It had a very rough idle and I had to keep pressing the gas to keep the car running. I drove about a mile away to get new spark plugs and on my way home the entire car just stalled out and stopped running on me. Usually happened when I came to a stop. I made it home and shut the car down. I installed new plugs and soon after new wires and tried to start it again but it wouldn't start. Then I bought a OBD-II scanner and got the PO300 code. Since then I've replace the catalytic converter, fuel PSI regulator, battery (because of draining), alternator, and fuel filter. Fuel pump sounds like its working because I can hear it engage, although I know that may not necessarily means it's operating properly, but in replacing the fuel filter I discovered that it had been a long time since its last replacement and the nut was rusted on. I put the new filter on and it was leaking fuel at the outlet side of the filter which also told me the pump was working. I repaired the line with a fuel line repair kit. No leaks and the car still won't fire up. I used an extension and hammer to tap onto the injectors to free up any debris just in case they were clogged. Also, when I went to relieve the fuel PSI from the fuel rail, when changing the fuel filter, there was close to no PSI released when I depressed the schrader valve. When I try to start the car it cranks maybe twice and then goes quiet with the exception that it sounds like something is still spinning. I don't know if its the sound of all the components the serpentine belt is wrapped around, alternator, compressor, etc. Or if it's the starter because of a weird grinding screech I hear on what sounds like the driver's side when I try to start the car, which I know is where the starter is located. I also have an idea it may be the GM TDM security that reads the chip key. I am so lost with this and at the end of my wits. I cannot afford to take my car to a professional mechanic who's more than likely going to try to sell me $1000's in parts before the problem actually gets fixed. Some one please help me.
Wednesday, February 6th, 2013 AT 7:57 AM