Please help! 2015 GMC Sierra slt 6.2 misfire

[Joseph J Pahler]

2015 GMC Sierra slt all terrain w/ 6.2. Engine was running fine then service engine started flashing and traction dash light came on. Engine started misfiring on cylinder 6 swapped coil with cylinder 4 computer still says 6 misfire. I replaced all injectors and spark plug with wire and started engine with same results…I’m going to do a compression test on it tomorrow but is there anything else I could be missing? Thanks 

[rlcole321]

Do you feel the misfire, or are you going by the CEL P0306 code?

[truckguy82]

I’m Assuming you are doing the obvious and resetting the codes each time.

[CamGTP]

Cylinder 6 is a AFM cylinder, could be that.

[JONBLARC7]

Pull the valve covers on that side and see if it's a broken valve spring.  Mine broke on number 5 at 105K miles.  It didn't drop or bend the valve.  So it was a quick and easy fix.  It's pretty common with 6.2's.  They have since updated the design of the valve springs.

[Joseph J Pahler]

So I removed valve cover and found a bent pushrod?? This explains the misfire

[Joseph J Pahler]

Just frustrated. took really good care of truck don’t beat it, always did oil changes every 3000

[JONBLARC7]

I happens but along as it didn't mess anything else up.  It's a pretty easy fix.  Still sucks I have a love hate relationship with my truck.

 

Mine broke a valve spring at 105K miles and it was cheap and easy fix.  Then at 125K miles it stuck a lifter.  So I pulled it apart and put a TSP 218/226 in it.  Now I enjoy messing with SS camaro's and mustangs 

[Joseph J Pahler]

On 8/23/2021 at 11:18 AM, rlcole321 said:

Do you feel the misfire, or are you going by the CEL P0306 code?

I was able to feel misfire it was shaking the truck when you gave it gas

[2018GMC]

Fixed? How many miles? Why did it bend pushrod? Mistimed AFM? 

[2018GMC]

On 8/24/2021 at 3:07 PM, Joseph J Pahler said:

I was able to feel misfire it was shaking the truck when you gave it gas

Fixed? How many miles? Why did it bend pushrod? Mistimed AFM event? 

Edited September 1, 2021 by 2018GMC

[CamGTP]

Maybe not beating on it was the problem lol.

 

I floor it in mine every single day.

[The Pig Dusters]

My truck is misfiring at idle and I have a code P0308. Did your truck make a noise with that push rod being bent??