2016 Silverado 3500HD violent miss under load 6.0L Gas

[agrasys]

My 2016 Silverado 3500HD misses violently when under load pulling a 10000 lb trailer up a slight grade. All engine parameters are in center of range when diagnosed by the dealer. They can't determine what is wrong. The miss is violent and gas consumption has to be in 7 miles per gallon or less for symptoms  to occur. Its been like this for 10000 miles beginning at 48000 miles. Changed to recommended top tier gas, 7500 miles ago and no change.  Engine rpm is at or above 2000 RPM when it occurs. Graphing fuel flow shows some noise in the flow reported. Have used GM fuel treatment,  Have not started throwing parts at it. Is it possible to fix? 

[davester]

maybe log fuel trims, knock sensor readings, spark advance while this is happening.  And are you using a tune?

[agrasys]

No tune, all stock. Have been using Shell mid grade, for the cleaning and the possibility of knock, with regular. dealer service manager rode with me and described the power loss violent, all his readings he said were in the middle of the range with his unit in the ODBII port. Its been a real stumper. I have odbii-Pro app and Bluetooth interface, but it doesn't read the timing advance. That is a very good suggestion, where as the timing isn't backing off far enough could cause knock sensor to ****** and maybe not at specs,  I'll talk to him and find out if he has that test in his unit. Don't see why he wouldn't but in all our conversations I never mentioned the timing. 

 

Thanks 

[truckguy82]

2 hours ago, agrasys said:

No tune, all stock. Have been using Shell mid grade, for the cleaning and the possibility of knock, with regular. dealer service manager rode with me and described the power loss violent, all his readings he said were in the middle of the range with his unit in the ODBII port. Its been a real stumper. I have odbii-Pro app and Bluetooth interface, but it doesn't read the timing advance. That is a very good suggestion, where as the timing isn't backing off far enough could cause knock sensor to ****** and maybe not at specs,  I'll talk to him and find out if he has that test in his unit. Don't see why he wouldn't but in all our conversations I never mentioned the timing. 

 

Thanks 

If you have bluetooth interface just use the torque app

 

also I chased something similar to this for awhile in my turbo civic when I was in my 20’s. I was fairly tech savy and built my own motors.

 

i took it to a mechanic, he had no idea

 

took it to a honda mechanic, he immediately goes “spark plugs”

 

i stupidly never checked my plugs

[agrasys]

Yes I have the blue tooth interface, thanks for the heads up on the Torque app. .. I hadn't heard of it, Was using ODBII-Pro And the spark plugs, yes a possibility and I just bought a set, so time to pull the fender wells and do the plugs. Tthanks to all for the second opinion.