Hesitation issue, car running poorly P0300, random misfire

Yes I have checked res. On injectors. All the same.I was told to replace pigtail on #2 injector and had a spare new injector. So just went ahead and replaced #2 injector also. Still no change.

02 grandprix. I put intake gaskets on after the car had been overheated and it skips while pulling a random multiple cylinder misfire and I think heads are warped is problem but wanted another opinion, please and thanks.

I think you are on the right track with the heads

Well I really thank you for your advice and maybe next time I will have account set up and will gladly donate to those who help. Thanks again!

Engine Mechanical problem
2002 Pontiac Grand Prix 6 cyl Front Wheel Drive

computer code is saying multipel cylinder missfire what do you think it could be and how can I fix it

I have checked the coil pack by takeing off the plug wires and it sparks between the 2 posts on each coil pack. Could it be the ignition control moduel?

2001 Pontiac Grand Prix GT 3800. Check engine light came on two weeks ago. It was a EGR valve problem. The vehicle was also missing with heavy acceleration. Changed the EGR valve and the error code disappeared but the problem continued. I found the wire to the 2 cylinder was chewed on by a mouse. Replaced the wire with no success. I decided to replace all the plugs and wires. Still had the acceleration problem. My mechanic hooked it up on his computer and it was showing a misfire on cylinder 2. The vehicle acts like it is not getting any gas. Mechanic checked fuel pressure but he only checked it at idle. He checked the spark and it was fine. Fuel filter was also fine. He checked the ingiters with a light tester and they were fine. Any ideas would be great. Also does the fuel pressure test have to also be done while moving?

I took it to a Pontiac dealer and they found out that it is a plugged catalytic converter.

Hi. My car, which I bought in May 2008, misfires when I accelerate it and hesitates to accelerate. I know that this indicates that one of the cylinders is not working, and may be the effect of a loose wire, broken spark plug, or an engine leak. I have no leak. The engine light started to blink. I turned off the car, restarted it, and the engine light came on again. What is wrong with my car, how can I fix it, and how much will the repairs cost? Thank you.

I have a 99 grand prix gt 3.8 non-supercharged. It has a misfire on cylinder 6 according to a scan tool. But the misfire is bad enough to throw the serpentine belt off. I have replaced the following trying to fix the misfire: plugs, plug wires, fuel injectors, coil packs, ignition control module, good compression with 108 on cyl 6, and no valve leakage, new fuel pump, fuel filter and relay, also has an aftermarket exhaust with a high flow cat converter done about a year before the misfire as well as new heads and gaskets that go with also done about a year before misfire. I am almost giving up on it please help.

Yes, hooked shop air to it and no leakage, I only tested three cylinders including #6 and they read around 106, and 105 then the 108 for #6.

I was wondering if you found out what was causing the issue you was having, because I'm having the same exact problem with my car. Dont think anything else can be replaced we have replaced everything. Ours is misfire on cylinder 2.

The car has developed misfires that occur at random and tend to go away on their own. I've checked the plugs, and plug wires and they're fine. The MAF sensor is new, and I cant hear a difference in the injectors using a steathoscope. Any help would be greatly appreciated.