P0301 Cylinder 1 Misfire and rough idle
 

First of all, this is strictly an informational/"thoughts on" post, as I have searched and searched for all of the causes of this issue. My hope is that it helps someone else in the future.

Truck:

2009 Sierra Denali, 6.2L L92, AWD, 6L80E (Mods in SIG)

Symptoms:

Leaving the house for the gym, my truck started dinging and the "Stabilitrak Off" / "Traction Control Off" displayed on my DIC. After this the check engine light was blinking followed by "Service Traction Control" / "Service Stabilitrak". The engine was idleing really rough, and there was a severe loss in power. It would go off momentarily, only to come back on with the same dinging and messages.

Troubleshooting Completed (no fix though:shrug:):

1. Went to O'Reily's and pulled the only code P0301 Cylinder 1 Misfire
2. Swapped 1 & 3 coils, and the problem stayed (P0301 again)
3. Swapped 1 & 3 plug wires and it stayed (P0301 again)
4. Ensured all conections were tight
5. Ensured all hoses were hooked up to rule out vaccuum leaks
6. Pulled #1 spark plug and it looked almost brand new
7. Pulled coil wire, started truck, and let's just say there is voltage
8. All fuses are good to go, verified through multimeter
9. All o2 sensor wires are intact, not frayed
10. All Fuel Injector wires are in good shape


So here I sit, dumbfounded, only to have my truck up at the Chevrolet dealership, feeling like I will have to give them my arm at some point this week as payment. I have looked this up, and the most common is an injector issue, but I don't have the guts to swap injectors. The main tech says that he has seen issues similar to this, where it has been a cam lobe, or a valve issue not letting enough air causing a misfire.

Anyone with any ideas?

Work up some courage and move injectors between 1 and 3.

That was the next step. I will see what they say it is tomorrow, hopefully not anything internal... I had read many places that said to do that, problem is, I did not want to pinch any O-rings and have a bigger mess on my hands. The only things I have never done on a vehicle were transmission, and fuel components, go figure...

Also, the engine sat, long enough for the belt to crack and create squeaks. So a gummed up injector isn't too far-fetched

injectors are super easy, dont sweat it.

you'll get a bit of fuel on you but whatever...

also I always replace the rubber o-rings when i would pull injectors

It most likely isn't the problem, but i would change the plug anyway. Since you have installed headers they have been pulled already, and could have been damaged. I had a plug on my turbo motor that looked good, but was cracked and caused the same issue.

This is so true. I've seen it many times. Plugs looked fine, but they actually got damaged in a header swap.

If it's not that, check the main ground where it bolts into the passenger side cylinder head. Make sure it's really tight. Loose grounds will also trigger the stuff that's happening to you. I have the same truck as you.

Interesting you should say this, as I just added a second battery to my setup. Either way I can assure you all of the ground connections are well made and tight, but I have seen wierder things. As for the spark plug, the headers have been in since I bought the truck, but I guess it is always worth a shot. I will update today when they call me.

I was looking at the process for the injectors. How long would that take usually, seems very involved?

By the way, really appreciate your guys comments.

Called them yesterday at 3pm. They said they were "just about to get to it", HA! They probably didn't even know what vehicle I owned. SO I am waiting another day then pulling it to go to another dealership.

Some dealer service departments just plain suck. :turd:

I hope you find a better one close to you, good luck!

Called them and it turns out there was low compression in cylinder 1. My guess now is that there is a hurt portion of the valve train.