[Harley1408]

Hello! can anyone help me with this?
I have a 2007 Pontiac G6 with code P0303, third cylinder misfire..

Already did the following:
Swapped Plugs
Swapped coils
Cleaned Fuel Injector

*Engine is running fine! no problems running! cant seem to figure this out... The engine light, comes on and off inconsistently once it is reset. Days, weeks... not directly after the light has been reset...


Anyone have any ideas or help!?

 

[waterfowler76]

spark plug wire?

 

[Pr0cl1v1ty]

spark plug wire?

Ditto, this is a more common problem then the others. I had a 97 Cadillac catera as my first car. Within 2 months of putting in a new engine i lost 3/6 cylinders. I did the same exact process as you and it turned out to be the wires.

 

[Coupe_Evo_V]

Already did the following:
Swapped Plugs
Swapped coils
Cleaned Fuel Injector

I too would say check the wires.. Just because they might look good doesn't mean they are...theres different methods to testing them...or just replace them all...

 

[GTPprix]

If you've swapped everything I'd say try a new injector and if that doesn't work possibly a bad ECM or broken valve spring would be me next check

 

[Harley1408]

the engine is running fine!

Hey Guys, Forgive me, this is my car but i am writing to you what my mechanic (father) has tried so far.. sorry if my lingo is offf.

He says that it is not a spark plug wire... he has checked/replaced those!.

any other thoughts,... the engine is running fine which i guess he is saying that is why it cannnot be a spark plug wire.