True- everything happens for a reason. Sometimes I need to hear it from others also- assume something you replaced is bad - or possibly bad connection(s) at the coils, wires or injectors? That's the bummer with doing a few things at once- is it fuel or electrical? Possibly bad plug wires or not seated enough? I'm also guilty of fixing what's not broke- cannot tell you how many times it has come back to haunt me....(last to come to mind of fixing "what's not broke" was the knock sensors - took a non-issue at the time & ended up doing twice)...

 

I'm not sure at this point, I'm going to assume it's electrical... because of the way it is responding... I'm waiting for the new heater core connection so I can't run it for the time being... I also upgraded to a stainless connection so that won't happen again haha... once I get those on I will swap out the Coils and harness and see if anything changes... 😔

 

look for G103 and G104 ground point locations. it is not just the firewall to engine strap. G103 and G104 are engine harness ground points. it includes the injector and coil ground points if i recall correctly.
oceanbrave had posted this pdf in another thread https://www.hummerforums.com/forum/a...745d1705190223

 

I'll check that out, thank you

 

You have a ground point on the left side of the engine block, just above the lip of the oil pan. You can reach it bending over the driver side. Should be two connections there, the smaller ring terminal is for your harness.

 

Recently rebuilt my engine in my 09 H2 and after putting it back in I had to fix a host of wiring issues. The backup light didn’t work cause the relay in the fuse box was fried. The power train relay connection in the fuse box also intermittently doesn’t work so that passenger side power to coils isn’t reliable.Of course GM discontinued the fuse box so I had to add some relays and do a work around from a good key on power source. Grounds going bad for the previous owner were the cause of the power problems and replacing the ground connection points fixed the issue. Now my dash lights are bright and not flickering any and everything works. Putting a fresh engine together really pointed out how bad the electronics had gotten. If the grounds were good to begin with the electronics would probably still be in great shape. The connection for the battery ground and coils ground are on the same place on my 6.2, drivers side behind power steering pump on the block. The connectors were really badly corroded and fragile. Those are the first grounds I would check out. Best of luck!