Getting a P0302 DTC

Well got all the plugs, wires and the coil packs replaced. Getting a P0302 misfire. This is only under hard acceleration. Like passing a slow moving truck on the expressway. I am thinking that the injector for cylinder 2 is having a problem. Should I move the injector for cylinder 2 to another cylinder, or should I just replace the injector? It is a 97 ponitac grand prix the engine has about 115K miles.

You had a prior post on a similar issue so I am referencing the thread so it minimizes redundant replies and possible confusion.

http://www.automotiveforums.com/vbulletin/showthread.php?t=922488

Prior to swapping out the fuel injectors you can run a noid light test to make sure the pulse width modulation from the PCM module is correct. Also, ohm out injector coil resistance. You should see around 11-12 ohms. Have you run any fuel injector cleaner additive through via the gas tank yet? Also, what is the fuel pressure reading?

Last couple of days, have not gotten much sleep. So I was not thinking about the other thread. Sorry about that BNaylor. I beleive that I have used seafoam in the tank, since I am not sure I will put another can in the tank, to see if that will fix the problem. I will measure the injector coil resistance to see if it is good.

I have put a can of seafoam in the tank of gas. Still getting a random misfire on cylinder 2. With the colder weather I have not pulled the injector and have not measured the resistance or swapped the injector to another cylinder. The cold reeks havoc on my lower back.

I missed it, do you have a 3100 or 3800? If the 3800, its really easy to measure injector resistance. I would start there.

Also bad, arching out plug wires could give you a random single cylinder missfire. As you accellerate, the pressures in the combustion chamber are higher making it harder for the spark to jump the gap at the spark plug. And since you know electricity takes the path of least resistance, the spark can arc right out of a bad boot or wire, or possibly you plug is "carbon tracked".

You could just buy a cheapo autolite plat plug and swap it in number two temporarily to see if the missfire goes away.

Have you tried switching coils around on the ignition module to see if the missfire follows a faulty coil?

Tim,

BTW it is a 3800. I have already replaced the plugs and the wires. Although it is possible, I do not think that is the real problem. The weathermen are saying that tomorrow the weather it is going to be much warmer and on Thursday it will be in the 70's. This is my chance to check the injector resistance. If that checks good. I am going to swap the cylinder 2 injector to cylinder 1 and see if the problem follows the injector. I will update as soon as I finish and figure what the problem.

Good idea! Sorry I missed the initial post. Gotta read before I open my big mouth sometimes. Oops

No problem, your up late.