2008 GM 5.3 with AFM

Jeff NWOH · Feb 29, 2016

Just bought an 08 GMC with a 5.3 with active fuel management. It has a bad lifter which doesn't seem to be terribly uncommon.

My question is whether or not to leave the afm in it. Cost is probably $100 more to just replace the cam and a few other misc parts and pay someone to turn off the afm in the pcm.

Seems to be a lot of discussion online about issues with the early afm trucks including lifters and oil consumption. It would obviously be easier to just drop a new set of lifters in and go, but I'm wondering if that's the best course of action.

Any experience or opinions?

Thanks, Jeff.

IAtractorKid · Feb 29, 2016

If it were mine, I would spend the $1000 to replace the cam and lifters and have the trucked tuned. Getting rid of the AFM, especially if you already have a bad lifter, is a no brainier to me. I haven't personally done it, but a few of the guys I work with have and are very happy with the results.

Ron-MO · Feb 29, 2016

I have not had any engine issues, but my truck is a 2011, and I believe most of the issues were with early versions. I did purchase the Range AFM disable and like it simply because it disables the AFM, preventing the engine from ever going into 4 cylinder mode. No real difference in fuel mileage at all, and drives much better since it was always short on power when it was in 4 cyl mode, and in 6th gear (my truck is a 6 speed auto).

Jim in rush co · Feb 29, 2016

I had a 2009 and no problems but traded at 49K miles have a friend that had a 2009 also and GM replaced the engine in it, oil use and lifters,I think there was a recall.

engineoops · Mar 1, 2016

Don't have answer to all your questions , but the lifters are roller lifters and very seldom hurt the camshaft . just put the AFM lifters in daughters 07 GMC AFM , and they were 54.00 each (8 AFM lifters and 8 regular lifters in this engine) . rock auto had the AFM lifters for 22.00 each but we were in a hurry. Problem started when they put 10w30 and Lucas oil stabilizer in the engine and it went haywire .ran bad ,shifted bad and lost 1 lifter . so proper viscosity is important 5w30. with the thick oil the pressure went up to 40 then slowly down to zero .proper oil and it's back to normal . seems there are some fine screen in the AFM solenoids and one under the oil pressure sending unit . I hope someone chimes in to tell if you could put all non AFM lifters in and disable AFM with device or reprogram . some guys disable AFM by removing sensor wire on brake booster or plug in device found on the net , but have not heard if all non AFM lifters can be used . hope this info helps someone . most people just get the lifters replaced and drive on. Eo

2008 GM 5.3 with AFM

Jeff NWOH

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IAtractorKid

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Ron-MO

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Jim in rush co

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engineoops

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