Mechanics

NEED HELP

2005 Pontiac Grand Am

Engine Performance problem
2005 Pontiac Grand Am 6 cyl Front Wheel Drive Automatic 109812 miles

ok we have changed the plug, wires, front oxygen sensor, cleaned the mass air flow sensor and changed the fuel filter twice and still over the last year my car keeps getting worse with missing when going under 40mph also had issues wanting to start on first try. At times when I turn it on to warm up I get into it and smell gas inside the car. Its eating through gas now and the missing is getting worse. I used to get like 320 to a tank now I get like 240. We are lost, I have been told it could be the fuel regulator or the cadillac converter. Please help befor it nickle and dimes me playig the guessing game.
thank you
Avatar
Trvsh5
June 10, 2010.



Is the check engine light on? With a idle problem like this it should be on and giving code(s). Otherwise there are too many things that can cause this issue, catalytic converter, bad PCM, vacuum leak etc.

Bluelightnin6
Jun 10, 2010.
The only code it give is the front oxygen sensor. Even after we changed it. Well it just came back on a year later the day after we changed the fuel filter and plugs again. The actual check engine light dont come on the Service engine soon light comes on. It runs good when going over 40mph but under that it missing a lot.

Tiny
Trvsh5
Jun 10, 2010.
Ok, well without that like I said it will be hard. Basically all components will need tested, ignition system, fuel system etc. Start with the fuel system. Test the fuel pressure to make certain it is within specs. If it is, test the fuel injectors to make sure all are pulsing good. Run some fuel injector cleaner through the system. Make sure vacuum hose is connected to fuel pressure regulator and that there is no fuel leaking into that vacuum hose.

Bluelightnin6
Jun 10, 2010.
Ok the error code it is giving is the random misfire code P300. So now Im really lost : (

Tiny
Trvsh5
Jun 11, 2010.
Could be clogged injector(s) as stated before, try the above steps and see if it helps any.

Bluelightnin6
Jun 11, 2010.
Ok thanks for your help

Tiny
Trvsh5
Jun 13, 2010.