5 months ago I bought a 07 Avalanche with the 5.3L Flex Fuel engine. While driving to work 5 days later after the purchase the truck went into V4 mode from V8, and started showing a service Stabilitrak / Check Engine / traction control off / and Low engine oil warning lights (even though there was plenty of oil on the dip stick). When cranking the truck it would shake badly but not produce a lifter tick sound, and exhaust produces a lightly visible smoke and smelled that's terrible, like unburnt fuel. I started doing research on what the problem could be and how to diagnose it when I came across Crazed Performance Repair's YouTube channel.
I then took off the valve covers to see if I could diagnose the problem. That's when I discovered that Cylinder #6 rocker arm and push rod both were not moving at all when turning over the engine by closing the loop on the starter relay. All other Cylinders were performing normal, but I noticed that it was extremely dirty and the port where the valve can be seen was cleaner and looked dry while the other ports look wet.
I replaced the valve spring for #6 (AutoZone Code reader said to replace the valve spring) and took the push rod out to example it for any defects. I also replaced the oil pressure sensor that is located on the VLOM. After putting the truck back together and starting it up I still had the same problems. Before I purchase the complete AFM / DOD lifter replacement kit I wanted to make sure that I am headed down the right path. I don't want to buy the replacement kit when I should have just deleted the entire AFM / DOD system because of a wiped cam lobe.
In my opinion, since the push rod will not move nor compress, the lifter might be rotated out of the groove its supposed to sit in. If that is correct, could it have wiped out the lobe on the cam shaft, or could it not be toughing the lobe at all?
any information, knowledge, or experience of this problem will be GREATLY appreciated. I can do the work my self but I am trying to not spend a ton of money on this older / high mileage truck. I was above to purchase the lifter replacement kit for $700 that includes the VLOM and the Range Technology AFM disable device to turn off the AFM/DOD system. What do you guys recommend me purchase? I promise to pay it forward and help out the next person that needs help. Thank you'll again for reading this post!