Misfire on DOD cylinders

[j91z28d1]

if the trims lock to zero when it starts missing badly. it might be dropping out of closed loop.

 

[Ceejkay]

if the trims lock to zero when it starts missing badly. it might be dropping out of closed loop.

I figured that out shortly after posting. So right now I only get 2mins to look at stuff before it zeros out.
@swathdiver so next steps I was going to do was pull the injectors, do a bench test of #4. Then put it in the #2 hole and vise versa. Also make sure all the connectors are correct and plugged in. If that doesn't seem to rectify it or if it doesn't follow, I'll pull the pass side valve cover and see if the lifters are working as they are supposed to.

Also have a full BTR vvt/DOD delete with truck Norris cam on the way. I'd like to get this fixed so I can get a decent data log to black bear, but if the lifters are the problem it won't matter either way.

 

[Ceejkay]

So did some more troubleshooting I guess you would say. Ran a compression test, probably should have started there. All the afm cylinders were low like 125-140 low while the other 4 were about 180-185. Pulled the valve covers and rocker arms were not sloppy and moved as they should while running. Plus side I have the pre tsb driver valve cover and will address that once the engine comes apart.

I'm thinking the afm switch or sensor what ever it is that controls that system, is failing or the valves have some serious build up. None the less ran some seafoam in the vacuum line and now letting it sit for a bit. Doubt that will clear anything up but you never know.

 

[Fless]

Is that PCV hose cracked or just an illusion?

 

[Ceejkay]

@Fless i think it's an illusion. It's pretty caked.

 

[donjetman]

You might want to do a piston/combustion chamber soak. The bad pcv in the driver side valve cover can stick the piston rings in their groove. Doing this and a new rear main seal cured my oil consumption 6+ yrs and 68k miles ago. Today it has 198k miles and never needs any makeup oil between 5k mile changes.
https://www.tahoeyukonforum.com/threads/2007-denali-cylinder-6-oil-foul.115601/page-2#post-1394161