I have been trying to fix my 2003 hummer h2 for almost two years now and I really moss being able to drive it. It was my daily for over 8 years. Kind of a long story, sorry. My 2003 hummer h2 has about 185k miles on it. We replaced the transmission about 4 years ago and it did well till about 2 years ago a check engine light came on. The code being p0300. We replaced spark plugs and wires (spark plugs are Delphi as we can not find ac delco.), valve covers, wire harness, had the top end machined, coil packs, fuel injectors, fuel pressure regulator, fuel pump, o2 sensors, cats, mass air flow sensors, lifters, push rods and even a new pcm (had programed). Well none of that fixed the issue but the blimp of misfire had calmed down but engine light comes back on with a few minutes of driving. We saved up for a while and bought a completely rebuilt engine from lkq and had it installed at a shop. Same code P0300 and now P0172 as well. Live data on scanner says mostly in 7 and 8. So the shop has no idea why new engine did not fix whatever is going on and we don't know what else to do? We don't have much money now but really want to get the truck back on the road. Who else can we see? Dealer charged us $250 just to say they don't want to be bothered with the problem on such a older vehicle I can't afford much more and feel so sad about it. Has anyone else had this problem? Has anyone else fixed this or can recommend someone we can have actually fix it? The new motor has a warranty but not for the problem the old one had. We are currently located in las vegas NV if that helps for anyone knowing someone. Thanks for any info! Sorry for long list.

 

I forgot what the codes you mentioned refer to but I saw 7&8 and it made my remember what I went through swapping the engine. For starters, the company that swapped the engine said it would need to be tuned (programmed) and they referred me to a company that does just that. I still had problems after that. Turned out that they left the spark plug heat shields off. Easy to do and an easy fix. I will pull my notes on the swap I did and see what programming needed to be done. Don’t get old, I cant remember what I did yesterday 😀

 

Did they replace the knock sensors , must use GM parts , crankshaft relearn?

 

have they preformed the crank relearn on either engines?

 

I know they did the crank relearn but I'm not sure of anything else program wise? Thanks so much for the info! That's crazy about the heat shields! I'll have my bf double check that for me today! Thanks!

 

Both engines did get the crank relearn

 

Knock sensors were transfered from the old engine. They did fo the crank relearn. I can't for the life of me find ac Delco spark plugs so they did delphi but they said that was a sister of ac Delco? I will definitely see about getting the knock sensors replaced asap! Thanks!

 

how does the truck drive, are there any signs of an issue and if so what are they?

Neal

 

Runs and drives great! Once in a while a little blip here and there at idle only but you have to be really paying attention to notice it. Otherwise she seems strong and fine but the dang light stays on so can't get smog to get plates updated

 

have you replaced the crank or cam sensor?