Hesitation/Stall on 16 DMax

2TrakR · February 15, 2016

2016 GMC Denali DMax 2500 HD

Part throttle, like taking off from a driveway or corner to slowly reach road speed, truck will not respond, stutter/sputter/hesitate. Hit the throttle about 3/4-full and it will get going, let off and hit part throttle and usually clears up.

Have 9K miles, have had this happen 4x now. Once we hit three times, I was concerned, 4 times and I've reported it to the dealer. They report no codes. Happened over 2 months. Different fuel, temps, etc.

In all 4 times, the truck was at operating temp, then parked for anywhere from 15 minutes to an hour, then fired back up and taken on the road.

No issues starting or light throttle to leave driveway/parking area.

Once on the road, apply part throttle (say 1/4 to 1/2) and the truck stumbles, does not respond, basically coasts.

Letting off and hitting it again with part throttle does not do anything to correct it. Put it down to 3/4 throttle or closer to WOT and it will take off, not quite as hard/clean as normal, but will go and then clears up. Last time I put it to the floor and held it there for 3-5 seconds (was unhappy with it). It stumbled worse, knocked and would not correct. Let off and reapply part throttle a couple times and it was good to go again.

Dug through here and see similar symptoms but seems like either high miles/dirty filter/tuned or consistently does this. Mine only has done it 4 times. I keep waiting for the next time to be "the end" with a tow truck as the solution....

Any ideas or suggestions?

The truck has had the injector pump replaced (was leaking). Also the turbo inlet gasket was replaced (diesel fumes in cab). I do not recall if the first time the stumble happened was before or after the pump replacement, but I think it was after. A couple of the times was after re-fueling the truck (but only a couple of the times) so I chalked it up to foam/other fueling related problems. Still was concerned since never seen this on my other DMax.

GM Tech/Troubleshooting notes make it sound like bad harness connections can cause this and I would lean towards that given how molested it's been under the hood for various (dealer performed) work.

Since this _seems_ to only be when the truck has gone through a partial cooling stage, is there anything specific or more prone to causing this failure to check?