I got me a Tahoe!

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21highcountry

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I did it! I got her home. My first Tahoe, a PPV. She's a 2014 with 150K on it. Ice cold AC BUUUT it has a Cyl #4 misfire. I swapped coils, new spark plug and wire on that cyl and no change.
When it was idling today, I can smell raw fuel and it had a little white smoke, but smelled no coolant or oil. I looked and noticed the air filter was FILTHY and the MAF wire inside was black. I pulled it and cleaned it, put a new air filter in. Still smells a little like raw fuel but not really smoking now. I'm wondering if the MAF sensor is bad. I'm guessing the #4 lifter is bad and thats why the code is there. I'm debating just putting in an LH9 6.2L non AFM and having it tuned instead of doing the AFM delete etc.

This thing was stationed in West Texas its whole life so it was disgusting dirty. I got the rear cop box removed, started cleaning everything real well.
Stuck open injector, I’d bet if you pulled the plug and put a camera into the cylinder that the injector is just dumping fuel, smell your oil to make sure there is no gas in it from the fuel getting past the cylinder rings, good luck.
 
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Nutro

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Already swapped to a good injector on that cyl and still have misfire on #4
 

Fless

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I'd suggest a test for exhaust gas in the coolant. Kits available to use on the coolant surge tank.
 
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Nutro

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Yeah I'm going to try that next but wasn't sure if they had a kit to use on vehicles without a radiator car
 

j91z28d1

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Well I finally pulled the valve cover and actually started it and let it idle. All rockers moved up and down EXCEPT intake on #4. It didn't move at all. Sad day.


so moves while cranking over like doing the compression test but when it runs it doesn't?

I feel like I've read that somewhere before


if so, i believe it's a vlom solenoid issue. the afm lifters are activated by oil pressure. the oil pressure unlocka them and the valves don't move. you might try blocking that oil supply off to the solenoids. then venting the pressure at the afm oil galleys and tune it off in the tune. might save you pulling the heads and doing a full delete.

a delete is still better long term but would be interesting.
 
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Nutro

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I hate to admit it but I think I'm going to have to pull the head SO, I am tempted to just toss in 2 new AFM lifters, delete the VLOM completely (Using an LS3 valley cover) and have it turned off in the ECM. If thats even possible while leaving the timing cover etc still installed.
 

j91z28d1

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if you use a non afm lifter Valley with afm lifters installed.. you'll have nothing but trouble. the lifters will collapse from built up pressure. it's been done here before. and guy that did it got unlucky and the lifter didn't pop back up. he was also working in a parking garage doing it. sounded miserable trying to bang on the lifter hoping it would pop back up so he didn't have to pull the head and replace. it finally did for him.


you gotta vent that oil pressure if you run afm lifters. any pressure in the ports that activate them, even if it's a small amount that makes it around the lifter from the hydraulic side is enough to release the pins and the lifter collapses.

best to block the oil supply with the plug kit and then cut the gaskets on the afm ports so no pressure can build up. this doesn't require you to pull the heads.
 

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