16’ Silverado - Shudder and misfire

[cs2480]

Truck was running flawlessly before this all started. I put a tank of gas in it because I was on empty. Almost immediately I noticed that when the engine was under a load at low speeds it was jump a little and hesitate to accelerate, however giving it more gas fixed the issue. Didn’t think anything of it and continued driving. Was merging onto the interstate when I lost power and saw the check engine light flashing and the traction control light was on steady. Fast forward to today. Took it for a test drive to see if it was ok. Going up a hill it was still acting up and now has developed a hard downshift from 2-1. Putting it in tow-haul and manual mode will make that issue go away. Anyone have any idea of what it could possible be.  71,7xx miles with a 6spd. 5.3 

 

TLDR; truck has shudder and misfire at low speeds with high engine load. Hard downshifting developed after a day. All started after I filled up. 
 

 

[diyer2]

I would drop the trans pans and change filter and fluid. Try a can of fuel system cleaner. Gumout multi system has PEA or for a stronger mix BG44K. 

[cs2480]

23 hours ago, diyer2 said:

I would drop the trans pans and change filter and fluid. Try a can of fuel system cleaner. Gumout multi system has PEA or for a stronger mix BG44K. 

I wouldn’t hesitate to tackle that project however it has a lifetime powertrain warranty that is offered through the dealership I purchased it from. Earliest they could be able to put hands on the truck is over a week from now. Not sure what to do at this point. Waiting vs trying to fix it myself. I believe it’s a bad gas issue that’s this is all origins from. However the hard downshifting makes me think otherwise. 

[Joseph J Pahler]

On 7/25/2021 at 5:59 AM, cs2480 said:

Truck was running flawlessly before this all started. I put a tank of gas in it because I was on empty. Almost immediately I noticed that when the engine was under a load at low speeds it was jump a little and hesitate to accelerate, however giving it more gas fixed the issue. Didn’t think anything of it and continued driving. Was merging onto the interstate when I lost power and saw the check engine light flashing and the traction control light was on steady. Fast forward to today. Took it for a test drive to see if it was ok. Going up a hill it was still acting up and now has developed a hard downshift from 2-1. Putting it in tow-haul and manual mode will make that issue go away. Anyone have any idea of what it could possible be.  71,7xx miles with a 6spd. 5.3 

 

TLDR; truck has shudder and misfire at low speeds with high engine load. Hard downshifting developed after a day. All started after I filled up. 
 

 

Just wondering if you found out what the issue was? I have a 2015 gmc 6.2 today my truck did the same exact thing. Computer says cylinder 6 misfire? Dealer mechanic said possible bad injector 

[cs2480]

13 hours ago, Joseph J Pahler said:

Just wondering if you found out what the issue was? I have a 2015 gmc 6.2 today my truck did the same exact thing. Computer says cylinder 6 misfire? Dealer mechanic said possible bad injector 

The truck goes in for diag today. I will update with the results. I believe it may be something to do with the K&N cold air intake. Truck runs flawlessly if ambient air temperature is below 72 degrees. Any higher and it develops the shudder. Haven’t had the check engine light come back on since the day I filled up. Nonetheless something is wrong and I’m hoping I get a good tech that knows what he’s doing. I will update accordingly. 

[cs2480]

Just now, cs2480 said:

The truck goes in for diag today. I will update with the results. I believe it may be something to do with the K&N cold air intake. Truck runs flawlessly if ambient air temperature is below 72 degrees. Any higher and it develops the shudder. Haven’t had the check engine light come back on since the day I filled up. Nonetheless something is wrong and I’m hoping I get a good tech that knows what he’s doing. I will update accordingly. 

Also, I had no stored codes of any sort after the check engine light started to flash, which I found odd. 

[cs2480]

Update for those interested. Truck is at the dealership. They checked for codes and found previous history of misfire and lean fuel. 

[cs2480]

Dealer called today. Bad injector in cylinder 3. 

[JimCost2014]

6 hours ago, cs2480 said:

Dealer called today. Bad injector in cylinder 3. 

Probably a long shot, ask them if you can have the injector, and ask what failed.

 

Maybe post some pictures, so future members know what to look for.

 

Happy to hear you now know what the problem was. 

 

 

[cs2480]

On 8/9/2021 at 11:35 PM, JimCost2014 said:

Probably a long shot, ask them if you can have the injector, and ask what failed.

 

Maybe post some pictures, so future members know what to look for.

 

Happy to hear you now know what the problem was. 

 

 

I will definitely call and ask. If anything I’ll make sure they give me a detailed explanation of what happened so I can inform you all.