Hello I need advice on my h3 hummer, I’ve gone through 3 delco new injectors and plugs and two coil packs and new injector harness and I’m getting cylinder 1 misfire and cylinder 1 malfunction on the obd2 reader, dealership thought it was the ecm and the replaced it and the issue is still present, smokes a little but dealership said compression was good , it’s back in for service because I think they misdiagnosed something. And also everything looks good too me no broken wires or etc. any advice?

 

Also it is a 3.7L with around 79k miles on motor and body with 142k miles aprox

 

Welcome to HF. You have been throwing way too much stuff & $ at your issue. What spark plugs are you using? The I5s require ACDelco direct replacements, virtually anything else will get eaten quickly and create problems.

Take a look at this, and avoid stealerships, the last place to take an out of warranty vehicle for service. Acts like it wants to stall/rough idle -No CEL -What To Do:

If you have done the full list and get to #7, do an induction cleaning. Search it here if you are not familiar with it.

 

Yes im using Delco spark plugs, and delco coils aswell there all new

 

Also the camshaft actuator solenoid is new, but my concern is how does a cylinder 1 misfire and has a fuel injection malfunction smokes white or blue something like that, compression is actually good thou, you think valve seals could be a issue?

 

Nope, I5 valve seals last forever, never even seen such an issue. I am thinking your valve seats have excessive carbon & crud built up causing inconsistent combustion. Hence, an induction cleaning.

 

The shop figured it out, ECM they replaced couple days ago and programmed, they figure out why it still was misfiring, some harness was rubbing or either melted but they fixed it, ill update the post tomorrow so anyone else w same issue can DIY it.

 

Do you have an update on what the dealer fixed? Or what they said was broken and replaced even though it was probably fine?

 

Issue was the harness to pcm was grounding out on the power steering pump, issue to fix it was repair the wire and tape it up and put heat resistant harness tape found locally or get one off of online

 

Another pcm replaced without failure. Read my previous posts, 99% NOT the pcm.