My wife's 2008 GMC Sierra 1500 developed a misfire on cylinder #1 which was accompanied by a strange chirping sound. I set up a dial indicator on the rockers to check the lift and sure enough the intake on cylinder #1 was about half of what it should be. This is what I found after tearing the engine down.

 

   

 

 

There were no spun bearings so the only machine work needed is to have the crank journals ground and the heads resurfaced. I am deleting the AFM/DOD garbage from this engine. I already have a new non-afm cam, lifters, lifter trays, valley plate, various bolts and gaskets, and the ECM has been flashed with the correct factory tune so I won't have any dtc codes to deal with. The pistons and rods are still fine so I'm just going to replace the rings and lightly hone the cylinders. There is no discernible wear in the cylinders and the compression was 145-160 across all cylinders. For those who have dealt with this I can now say.....

 

 

Had the same thing happen on a 1997 Pontiac Grand Prix GTP. Engine had about 180k miles at the time so I scoured the junk yard for a cam and lifters and happened to find a wrecked well cared for Camaro as the donor vehicle. Probably should have tore the GP engine down then and freshened it up but I hate working on my own crap so I just did the minimum for it to run. About 30k miles later it threw cylinder 2 rod and knocked a hole in the block. I put a $400 Series 3 3800 Craigslist find in it and traded it in on the 01 Dodge I have now.

@04Mach1 It's a known issue with the AFM (Active Fuel Management) lifters. This engine would still be running strong if not for that garbage. 

  my wife’s 2004 Tahoe with the 5.3 and no AFM is pushing 300k , had it since practically new and engine still going strong. 

 

now I just wished I could say the same for daughters 2013 Hyundai, it’s barely got a 100k and smoking like a freight train, might be replacing that engine for her, she is not to blame though she been away at college for 3 years and left her car home for me and the wife to use.  

Edited November 11, 20186 yr by 01cummins4ever

54,5xx miles on my '16 Silverado bought new.  AFM has been deleted on my truck via running in M5 or by using the Range AFM delete module.  In all the miles on my truck.............I'll bet less than 10 miles have been in V4 mode.

 

Still pull 20+mpg on the highway running 70mph+.

Have there been a lot of issues caused by the AFM on the new gen 14+ 5.3's?

 

I have heard of many with the earlier AFM engines but havent heard of issues yet with the new gen engines.

 

My parts runner ("15 1500) I also utilize M5 when possible just to disable that dang AFM.  The AFM is annoying to me as well and with the Hi Flow muff is certainly audible when it changes. The wifes classic body style 1500 with no afm on the 5.3 with over 200k still runs sweet and my old 2001 Tahoe with 300k did as well before I sold it. Thankfully no AFM on our 15 Camaro.

 

So @dorkweed , the Range box simply plugs into the OBD connector? When removed, Undetectable if the GM warranty is needed? I had considered a tune but the only thing that truck needs imo is to disable the AFM.

On 1/25/2019 at 9:51 AM, BrianAtSmarty said:

Have there been a lot of issues caused by the AFM on the new gen 14+ 5.3's?

 

I have heard of many with the earlier AFM engines but havent heard of issues yet with the new gen engines.

 

My parts runner ("15 1500) I also utilize M5 when possible just to disable that dang AFM.  The AFM is annoying to me as well and with the Hi Flow muff is certainly audible when it changes. The wifes classic body style 1500 with no afm on the 5.3 with over 200k still runs sweet and my old 2001 Tahoe with 300k did as well before I sold it. Thankfully no AFM on our 15 Camaro.

 

So @dorkweed , the Range box simply plugs into the OBD connector? When removed, Undetectable if the GM warranty is needed? I had considered a tune but the only thing that truck needs imo is to disable the AFM.

 

 

They claim that the Range AFM delete module is undetectable.  I would think that if they want to dig deep they could find out how many times that AFM is active per key start ups or something like that.