Which cylinder is the misfire? If 1,3,5 or 7 it could be impending AFM failure, might check compression on all cylinders.

 

[QUOTE=in2pro;448619]Which cylinder is the misfire? If 1,3,5 or 7 it could be impending AFM failure, might check compression on all cylinders.[/QUOTE

The code has been p301, so cylinder #1. I will take that into consideration thank you... i think i will replace the injectors for now. After that inwill definitely check the compression... even if it fixes my misfire.. ill give it a look anyway

 

August 22, 2020:
- after 3 hrs on the highway, CEL blinking.
- Scanned P0301 code at 297050km or thereabouts.
- Changed Coil, spark plug for AFM cylinder 1, no change, still missing.
- Engine very rough due to misfire.
- Repair done at 297131: problem diagnosed as Cylinder 1 AGM lifter collapse. Entire driver side bank lifter and head gasket and other gaskets replacement. Camshaft OK, no wear.

Oct, 24, 2020:
- Tahoe at 298000km or thereabouts.
- No issues, noticed what I think was chevy shake at or above 110kph, but would be on or off.
- Same thing that was the warning sign the first time.
- Truck rested for 2 days before next use.
- On the highway for 1.5 hours going 110kph or so, CEL comes on and blinks, but there is no sign/shake of a misfire.
- Read P0301 code AGAIN (this lifter was replaced), as well as P0521 code (At this point I'm super pissed that the repair didn't change anything)
- Pulled over, stopped the engine.
- Started again, no problems. Then CEL blinks on again, and the Oil Light blinks.
- I notice the oil pressure gauge steadily and quickly falling to 1/4 as I'm driving on the highway.
- OBComputer tells me to immediately stop the engine due to dangerously low oil pressure.
- I check oil levels, all OK. I start driving again, and oil is perfectly within the normal range, then 10 minutes starts steadily falling again, to 1/4 on the gauge, and CEL starts blinking again. I pull over, repeat an engine stop again, get back on the highway, and then go. CEL stays on solid but no longer blinks, oil pressure is fine, but then steadily starts going down again.
- 20 minutes later, the engine starts shaking hard, for a misfire. Then, after getting off the highway, the engine does auto-stop at a light, and then when restarts, no misfire.
- In city driving, no oil pressure issues, CEL light is on but not blinking.
What could this be after the f*****g $3k repair that the same thing happens again?
Is it the AFM system? It's a 6.0l V8 LFA Vortec with AFM on lifters 1, 4, 6, 7 on a 2008 Tahoe Hybrid 4x4.

 

Just got my 2007 Avalanche back from my mechanic as I have encountered the same issues as everyone on here. My mechanic said he has never seen a camshaft so beaten down like this. There has to be some design flaw causing this issue. Needless to say I need camshaft and lifters but have opted to scrap it due to the high mileage and age of my vehicle. Sad because I really loved this truck.

 

The repairs for this motor even with high miles could be worth it. No payments for another truck speaks volumes. You mechanic can replace the lifters and camshaft with LS7 parts and disable the AFM. not super expensive and I think you will be happy. I know if I had your truck and I liked it that would be the route I would take.

 

for about 1k in parts and whatever the mechanic charges for labor you can fix this.
https://www.texas-speed.com/p-7379-t...2-engines.aspx

 

Nah. The body is rusted out, huge hole in one of the rocker panels and tailgate. I may sell it to someone who wants to part it out. I have another vehicle so it is not like I am at a complete loss. Thanks though.

 

I understand. My 2007 Tahoe is in Mint condition. No rust, no dings, paint in real good shape. I have already did the work on mine and with almost 300k miles I will never part with it. no payments so it is something that is good. Even if the motor takes a crap I will get a new/used motor and for under 2k bucks it will be on the road again.

 

Well this is cool.

 

It is however the problem still exist because the AFM lifters are still in place. They are the problem child in these motors. Replacing these lifters with lS7 lifters and the cam fixes everything.