2009 Avalanche LTZ cylinder 6 misfire

[Holly]

My truck started getting a ticking sound around 145K miles whenever my Rpm's would get around 2500-3200. Computer code reads cylinder 6 misfire. Replaced all plugs and wires. Still throwing code. Switched around coil packs and still received same code for cylinder 6. So ruled out coil pack. I figured I had a lifter issue but wanted to make sure. Took the truck to Chevy and it got diagnosed as bad lifter. Took engine apart until I got down to the lifters. Replaced all lifters. Figured I might as well while I was in there. Also replaced the gaskets. Also Replaced Mass air flow sensor. Put everything back together, reset computer, started the car and I was very relieved that my truck ran perfect! Ha! 2 days later I'm driving the truck and all of a sudden it starts running rough, service stabili track light comes on, traction control and the engine light. When I look under the hood my engine is bouncing up and down. My truck is shaking like a hot rod. My air ride went out right before I changed the lifters. Like literally the day before. I replaced the whole compressor hoping maybe that was throwing off the computer. Nope. Air ride is fixed and I can't even drive my truck because of how the engine is running. The day before I replaced the lifters I took the truck to tire kingdom to have them run their free A/C check because when I accelerated my cold air would get somewhat warm. After they checked it, said everything was fine with my A/C, they pull my truck around and my truck was doing the same thing it is doing now. All same lights were on, engine running rough, shifting a little hard when slowing down from 2nd to 1st. The mechanic could not figure out what happened and I just chopped it up to the bad lifter and changed them the next day. Now I'm ready to pull my hair out! What the hell is going on?!?! Any suggestions??? Hoping to fix this problem because i would like to hold on to this vehicle. I love my truck!

 

[Erik Thoreson]

I would guess that since it happened a second time that the AFM lifters are not getting oiled enough. There is a thread on silveradosierra about the oil pump pick up o-ring being the culprit. What is your oil pressure like? Could also be a passage in your Valve Lifter Oil Manifold (VLOM) is plugged up causing oil to not get to a specific lifter.

Or maybe possibly you didn't get it reassembled correctly after your first rebuild?

Those are just what come to the top of my head. Could be something entirely different.

 

[Holly]

I would guess that since it happened a second time that the AFM lifters are not getting oiled enough. There is a thread on silveradosierra about the oil pump pick up o-ring being the culprit. What is your oil pressure like? Could also be a passage in your Valve Lifter Oil Manifold (VLOM) is plugged up causing oil to not get to a specific lifter.

Or maybe possibly you didn't get it reassembled correctly after your first rebuild?

Those are just what come to the top of my head. Could be something entirely different.

Thank you!