Rendom misfire

[kbuskill]

Ok, so I have good news and bad news.
Goods news, it's a very nice truck. Even AC works. Got lots of blows and whistles.
I ran Toque on it and shows that all sensors, it had access to, check out fine.
Here's the bad news:
1. Service stabilitrack is on all the time. Now, truck had brakes damaged during towing, apparently, driver hooked up chain across the brake line or bleeder valve. Allegedly, guy that was "working" on it fixed it, but light is still here
2. Misfire cylinder 6. That's one and only error code. Truck idles very rough but, if given gas, stabilizes. There is brief mechanical noise when gently pressing gas pedal. 3. It SMOKES. grey, oil burning type smoke. So I am not even going to try to move ignition coils from cylinder 6 to another one - it clearly is blowing oil into combustion chamber.
3. Tailgate does not open. Neither from the inside button, nor from the one on the handle. Guy told me, it's bad handle button, "typical" for Tahoes.
Outside of the normal after auction dirtiness, it is in very good shape. No rips, tears, comfy seats, warmers work fine. Push buttons emblems worn out on driver side but I already have new decals and 2 new keys/fobs.
Driver side door previously was stuck shut too but, given a nudge from the inside, now works fine. Maybe same needs to be done to the tailgate.

Ignore the Stabilitrac light until after you resolve the misfire.

It is standard operating procedure for the ECM to disable Traction control and Stabilitrac when there is a misfire to eliminate those systems as a potential cause of the misfire.

Also cylinder 6 is an AFM cylinder. I would pull the passenger side valve cover and watch the rocker arms on cylinder 6 while rotating engine.

 

[ukrkoz]

Yeah, I figured that much about Stabilitrack.
Another good news - tailgate opens and closes from the inside button and remote. Handle buttons don't work or, I am not doing it right.
Found milkshake in oil cap.
Will have new mechanic come and do diagnostics at my place, with me present, in few days. He'll determine, if it's head job or engine swap.
So far, we are leaning towards blown head gasket, with milkshake being present.
I, also, swapped #1 and #6 coil packs and it didn't change anything. So it's definitely #6. I'll sit tight for the next few days.

 

[kbuskill]

Yeah, I figured that much about Stabilitrack.
Another good news - tailgate opens and closes from the inside button and remote. Handle buttons don't work or, I am not doing it right.
Found milkshake in oil cap.
Will have new mechanic come and do diagnostics at my place, with me present, in few days. He'll determine, if it's head job or engine swap.
So far, we are leaning towards blown head gasket, with milkshake being present.
I, also, swapped #1 and #6 coil packs and it didn't change anything. So it's definitely #6. I'll sit tight for the next few days.

What does your oil on the dipstick look like?

Milkshake in the oil cap doesn't mean a whole lot, especially in colder climates with short trips that don't allow the oil to get up to temperature to boil off the condensation.

You could also swap the #6 fuel injector to see if that makes any difference but in reality pulling the valve cover is much quicker and easier to determine if it is a collapsed lifter.