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2008 Sierra 1500 5.3 AFM cylinders(lifters)LH6

steelcity73
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steelcity73 Enthusiast

steelcity73

Posted
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Driving and sabilitrak/traction control lights came on then truck started running sluggish.  Got a P0304 misfire(Innova 6030p scanner), changed plugs, wires on all cylinders also replaced coil on #4.  Have ticking noise now, loudness increases with revving of engine.  Was going to do compression check next, haven't checked injector yet, I was wanting to know which cylinders are involved with AFM, and if it could be a collapsed lifter which AC Delco lifter I would need?  Thanks for any suggestions.

dsr611 Senior Enthusiast

dsr611

Posted
Posted

Cylinders 1, 7, 4, and 6 are the AFM cylinders, if I'm not mistaken.

 

If it is the lifter, you'll want to check the cam to make sure it wasn't scarred up also.  Are you planning on going back with AFM lifters (no way in hell I would go back with the same lifters that givve me problems to begin with)?  If it was my truck and you plan on keeping it a while, I'd check with Texas Speed and Performance and get an AFM/DOD kit and replace all the lifters (not just AFM lifters) with lifters from the previous gen 5.3 and cam and completely do away with the AFM BS.

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newdude Senior Enthusiast

newdude

Posted
Posted

1, 4, 6 and 7 are the AFM cylinders.  

 

However...

 

If you plan on keeping the AFM system and not deleting it, don't just fix the one cylinder.  Change all of the active lifters on that bank that has the failure so total of 4 AFM lifters and also change out the VLOM in the valley of the engine.  I'd also replace the lifter guides they sit in as well.   

steelcity73 Enthusiast

steelcity73

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Thanks for all the suggestions, I'm self employed and it's a work truck, I've already redone ABS, brakes and a new transmission, so I'll probably be holding on for a while.  I'm just running out of money so I was hoping to fix myself.  I did compression on #2, used Autozone rental, that was beat to hell and missing parts, but got a 90ish PSI on idle and a 150ish on rev.  On cylinder #4 had no compression reading, new plug on #4 had more oil than #2, I knew I should've stayed with my Fords :(

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

Compression tests are done with the engine off and you just crank it, never need to run the engine doing a compression test.

 

But if cylinder 4 has no compression you should pull the valve cover to see what it looks like. Rare chance a valve spring broke but it's likely a failed lifter. Time to pull the cylinder head and replace some parts.

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