Daniel1986

Hi all,

I'm new here and just want to introduce myself first.

I'm Daniel and living in Germany and I'm driving an 07 Suburban with an good old 5.3 l flexfuel engine with AFM with already 250000 miles on it.

I'm currently facing issue with some missfiring on cylinder 6, but only in idle. Traction Control lamp pops up and Check engine light blinks as well. It disappears after a few Seconds of driving.

History. I had a ticking noise from the engine in December 2020 together with some small random missfiring and I decided to replace all lifters. So pulled the heads and swapped them all out. Also installed a new VLOM to make sure everything fine. Put also some new O Rings and filters on the Injectors and changed out some other gasket as well.

Everything was fine after that, still some random misfiring but no ticking noise anymore.

Just a few weeks ago one of the lifters on cylinder 6 collapsed. Pulled the head again swapped out all lifters, changes valve stem seals and grinding in the valves. installed new headgasket und intake gasket and so on and Assambeld everything. Then I was facing low oil pressure droping nearly to 0 PSI after a few minutes which was probably my fault as the oil was quit old and oilchange was overdue.

Decided to flush the engine and change the oil. Changed also the oring on the oil suction pipe(is that the correct word? *lol*) Oil presure was just fine after that and steady on 40psi in idle.

Still misfire in idle on number 6... Cross changed the coil, no change. I will try a new spark plug but the old one should be fine as they are pretty as well. Ignition wires are fairly new as well. No Oil consumption at all, no visible damages on the pistons or liner no smoke.

Does any body have an idea what else can cause this propbelm.... Im running out of ideas...

Thank you for your ideas in advance.