UPDATE:

He's gone through everything on the truck 3 times now. They have checked every sensor on the truck for bad wires, grounds, corrosions etc. On Wednesday night he and a friend of his narrowed it down to Cylinder #3. They learned that the compression in that one cylinder is different than the others, it's having a "breathing problem" in lay persons terms. The recorded the data and he sent it to a buddy of his who analyzes the data in engines to help detect the problem. The only code is a random misfire. Today he's going to pull the valve covers again and check each cylinder one by one. I'll keep you posted.

 

He'll find it just may take some time, sounds like he is getting closer.

There is a long list of GM test procedures for the P03000 and it takes a while to work through them

Make sure to let us know what it is when he locates the issue,

Neal

 

Here's a thought that might save you some cash, you can swap the coil pack and wire with the adjacent bank cylinder and see if the misfire moves. You had mentioned a compression difference, how much? Also, you may want to consider a seafoam spray treatment into the throttle body to remove carbon buildups. Glad to here you are making headway.

Dan

 

sounds like it narrowing down to a lifter...

 

forgot to ask if your model has cylinder deactivation. sometimes a damaged cam and lifters will cause miss fires. common on all make cylinder deactivation engines. super common on dodge hemi as well as gm and ford

 

None of the H2's (LQ4, LQ9 or L92) had cylinder deactivation or AFM. GM didn't start that crap until the release of the L-94 in the other brands. (Thank goodness for that, lol)

 

The data came back that he sent off to a guy who looks at engine/compression readings and he wants him to take some measurements on the camshaft. Sounds like we're getting closer each day. I'll keep checking back.

 

Reality check:
Your mechanic has been monkeying with this H2 for 7 weeks now.
Can you trust the conclusion that he comes up with, and are you willing to throw more $$ at that experiment?

A worthy GM dealer would have had this diagnosed in a few hours tops.

I understand that you have loyalty to your mechanic. Nothing wrong with that.
But sometimes you just have to move on and fire your mechanic.

Friend, just trying to save you more weeks of time and bunch of money..
You bought an H2 more than 2 months ago. Most of that time it has sat with some mechanic dude who can't figure it out.
To put it into perspective, that is 90% of the time.

YOU should be having fun it it instead of your mechanic.
Unless you enjoy pain?

 

First I can't agree with you more. But here is my dilemma. I now know he's going to have to go back into the engine. Since he's already been in there once, he's not going to charge me to do it again. If I pull it now and bring it to the dealership, I'm going to have to pay for them to go back into the engine and I'll be out more money. It sucks it's been there for 2 months now, but it will cost me way more money to have GM look at it and make the repairs with the information I have now. I'm also hoping that any parts related to the small compression issue it's having will be covered under the POS warranty the dealership sent with it.

 

so what did they find?