P0302 Engine Code

[H2Much]

So, started up my ride yesterday and got the check engine light. Pulled the code and it looks like the P0302 2nd cylinder misfire. So, mechanics out there, I run Chevron premium all the time. I had the plugs changed about 10,000 miles ago and I am pretty sure the wires at the same time. What else should I look at doing? I know that it could be several other things, but I am wondering what I should trouble shoot first based on the fact that I already run awesome gas.

Thanks in advance for any input.

[jsbihn]

Could you explain to me how you pulled your code?
I havent found anything on the web to explain how to pull and rest codes on my '03 H2

BTW,
If I am wrong, I am sorry, but I believe these engines are very similar to the engines in my Vette, so if thats the case, I would check the ignitor / ignition coil pack.

[H2Much]

I have a handheld code reader that I pull them with. Thanks for the tip too!

[HUMTECH]

swap ignition coil with another cylinder and see if misfire follows coil. Make sure plug wire is fully seated on plug have seen them come loose after plug replacement as much as 20000km after they were done

[H2Much]

Thanks as always for the good info Humtech. Yah, this thing has been on and off for the last few weeks, comes on, goes off. I have checked wires, plug, etc., so I am thinking I may need to replace the ignition coil on this thing. Another $100, down the drain!!!

Question for all of the smart people out there: Why did Hummer decide to go with cheap stuff on their what used to be $70,000.00 trucks? WTF?

[H2Much]

Still having the P0302 code firing. Tried several things thus far: swapping plugs, swapping wires, replaced the coil on Cyl 2, still popping the code!! On top of this, not feeling any knocking at all or misfire while driving. Getting fed up, sick of this- Could this be a sensor? What else could it be?

Any help anyone can provide me on this would be great as my mechanic is out of ideas too - thanks.

[H2Much]

Bump... still getting the code popping. Thought I would bump the thread again, see if anyone else can give me a direction on this since my mechanic is unable to troubleshoot any further. Any other sensors that I could be missing here that maybe need to be replaced?

[HUMTECH]

Next thing i would try would be swapping an injector from another cylinder to see if the misfire follows the injector.

[HUMTECH]

Does the code set when the engine is hot? Cold? Dont matter on temp?

[H2Much]

Usually pops when I have been driving for just a few minutes, so I wouldn't say its hot. Already tried swapping the injectors as well. What is weird is that I do not feel anything different at all about how the engine runs when it pops or doesn't, engine seems to run the same. No apparent misfiring going on, no recognizable loss in power; I would assume that the 8 cylinders would be quite obvious if there was a misfire from driving it.

[[__--MUD--__]]

Question what is telling you there is a problem first....maybe there really isn't.

Knock sensors starting to flake out? Been a number of people posting some nasty looking sensors from water and mud sitting on them. Poor job sealing up that cavity from the factory.

[H2Much]

That's what I'm thinking when I say "other sensors" as I am not feeling running or idling issues, so I want to say that there is a sensor issue going on.

Also, one more detail - This code didn't start to pop until after I installed my CAI; would there be anything there that could be causing the issue? I would go back to stock except my stock intake was muffed up and mashed into the throttle body to where part of the opening of the tube was bent inward closing off some of the open circled area of the throttle body - freakin' idiot whoever owned this before I bought it. Anyways, I didn't find this out until I had to take off my intake to do plugs; figured it was a good time to upgrade to CAI.

[[__--MUD--__]]

Sure there are no loose wires, connectors, plugs, wrenches, screwdrivers sitting on top the motor somewhere?

[H2Much]

Nope, double checked everything when I did the headers. just to make sure. Must be a damn ghost living in there or something.

[HUMTECH]

Low compression, sunk valve seat, carbon build up on valves, excessive leak down in that cylinder, weak lifter

[HMH2SUT]

I had the same issue few years back turned out to be dirty injectors on numbers 2 and 7. I Replaced those 2 injectors cleaned a bunch of sand and debris from the fuel rail and all was well.