Started with a slight miss, then DOD lifter failure, now back together and a solid miss that I can't diagnose, need help!

[JD Derryberry]

I'll really try and keep this short, months ago our 2013 Denali 2wd started a slight miss, there was never a CEL on but the stabilitrack and traction control warning came across the little screen and the traction control light came on in the dash. Not sure if it has to do with my actual problem or something unrelated, just wanted to share that part in case. At that time it had 155k miles and still OE everything so I ordered a full tune up kit with plugs, wires and coils. Life got busy then I got sent out of state for 3+ months of work so FWD 6 months and I'm then sitting at 165K miles and I get the knocking and valve train noise common with the DOD lifters. Diagnose and pull valve covers and have a stuck lifter on #6. Pulled the engine down to a short block, video scoped the cam and all lobes looked surprisingly good and had no grooves or pitting so I rolled the dice and only did new DOD lifters. I put it all back together and got it running and sounds smooth and no valve noise but cylinder #4 is missing and a P0300 code popped up. Did diagnosis and have good spark, tried swapping hardware and coil with another cylinder to see if miss followed and it did not, staid with #4. Next was check compression and have great compression, checked injector and had power at the injector but was thinking I know it's getting air and spark so had to be no fuel right so maybe injector was plugged so I replaced that one injector and no change. Someone mentioned to check injector pulse, I have a scanner tool that may do it, but I don't know how to use it well so did the 3/8" extension to the ear trick and #2&6 have an almost muffled tick while it's running, #4 has a very distinct clear tick - not muffled at all and sounds very different to the other 2 I checked. My thought is no injector pulse so went down that rabbit hole and see a bunch of talk about a PCM so thinking that might be a culprit.

After I tried to check the injector pulse, I figured night as well drive it and see what happens so I cleared the codes, opened the misfire graphic app on the scanner tool I have and went on a drive. I back out of the driveway and went about 10 yards and CEL came on along with the stabilitrack and traction control warning on the little screen and the traction control light came on in the dash then something weird that was not happening before, when I started to accelerate hard it fell on it's face and struggled to pick up speed and watching other cylinders on the app, others cylinders started missing as well. I drove 6.4 miles in about 10 minutes, #4 misfired 13,691 times and 6 of the other 7 cylinders misfired between 1 and 14 times. I'm not sure what can cause these type of symptoms.

Anyone have any ideas?

 

[OBSandaNNBS]

This area is not my forte, but I think the ECM sounds like the problem. The HIGH number of misfires on same cylinder after switching hardware indicates an electronics issue.
Also posting to bump this up...

 

[solli5pack]

Double check and make sure the correct wires are connected to the correct injectors...

 

[Dustin Jackson]

While the misfire is more pronounced in one cylinder it seems to be happening across the board which kind of makes me think it's not to do with the cylinder itself but some other part of the system.

Next thing I would do is monitor your fuel trims and report back

 

[j91z28d1]

where did you get the new dod lifters. I've seen more than once if you didn't use oem or millings afm lifters, at least one of the 16 is an out of the box failure and gotta go back in again.

sadly, it was probably time for a full delete kit as a lot of times the mechanical faliues of dod hardware is from a failed electrical parts, or oil supply. from posts here it seems a repaired dod/afm never lasts like the first oem one.