2016 Duramax (horrific vibration)

Brad Clayton · July 20, 2022

Been a long time since I have posted, but I have head scratcher here.

2016 Chevy 3500 HD vin# 1GC4KYC80GF236554 MILES= 124,000

The truck has a tune on it and things weren't monitored as well as they should and it blew a hole in a piston. The owner drove it to the shop I work at instead of towing it. My man was dead set on gettin her there under her own power, (smokin like a freight train, about to shake the dash out the passenger window, top speed of 35 mph, you know) :rolleyes:

The engine was replaced with a long block and all was right with the world. Customer picks up and comes right back, says it has a vibration that will chatter your teeth. This is verified at 65 to 75 mph under light accel.

Lots of chassis stuff has been checked and found ok, the usual wheels, driveshaft, ect.

I noticed that if the RPM deviates too much, then the vibration goes way, like down shifting, or unlocking the torque converter.

When the truck is acting up, the fuel trims for 3 and 8 max out at 25.

Here is the kicker: if you do a crank relearn, it takes about 70 miles of driving to get the problem to reoccur. Hence the reason the truck was given to the customer the first time with no issues.

I appreciate you guys reading this and any thoughts would be super! I am not a Chevy guy but I am convinced that GM hates their techs.

jimmy57 · July 28, 2022

Are the injectors re-used and in the same holes so the quantity codes are correct? I am always irritable as hell when I work on LMLs. A little less so for the other versions but still angry. From too little engine bay space to things that don't have to be stacked, being stacked in the way to fan stator in the way of alt. bolts when it just didn't have to be that way. This is a far from complete list. PStroke 6.7 is certainly not without some offenses but I don't find many that seem like purposeful abuse like on Dmax.

Brad Clayton · July 31, 2022

Oh, I agree with you whole heartedly on that sentiment. The injectors are in the same spots and 3 and 8 were replaced and IQA's imputed accordingly.

forddieseldoctor · July 31, 2022

It’s got a program in it…. But can it run without it? Or is it modified to the point of running stock is not an option?

Brad Clayton · September 20, 2022

Sorry for the late update, customer is driving the truck and it's been "out of sight out of mind". So the programmer can be removed and the truck runs, it just says it will derate in "x" number of miles. Concern is still present. The biggest issue I have is you can't get the thing to do a crank relearn. I don't know. I'll post an update if I get something. I have basically washed my hands of it now.