A few months ago I bought a 2007 GMC Sierra (new body) with 150,000 miles on the clock. It has the LH6 in it. It has since gotten cold outside and when I start it in the mornings It has what I am sure is a rod knock. It goes away after the engine warms up. It has good oil pressure. I have always been a ford guy and wasn't too familiar with these engines otherwise I would have avoided these early AFM engines like the plague. It sounds a lot "deeper" than a lifter click. I have removed the valve covers and confirmed that I don't have a collapsed lifter or flattened cam. The thing consumed over a quart of oil in the last 2,000 miles. I had a cylinder 1 misfire and when I pulled the plug it was pitted and the porcelain was cracked showing tons of detonation. I replaced the plug and that fixed the misfire. All the other plugs look great.
Onto my question. With all these issues an the reputation of these AFM lifters and oil consumption I kinda want to get ahead of it and plan on putting an engine in it. This is my daily driver so i need to minimize down time. I was looking to get a block and get it ready to go in the truck (as money permits) so there is no huge rush or surprises. The problem is these specific LH6 Aluminum blocks were only used from 2005-2009 and are not the easiest/cheapest to find. The LY5 however is the iron counterpart to it and cheap and easy to find since they produced them 2007-2014 and were more common. I don't care about the 100lbs. Does everything bolt up? And would the computer freak out? I plan on eliminating the AFM and putting some trustworthy lifters and a cam in it so I will need some computer work done anyways hopefully it can be programmed enough to handle a different block? Would someone with HP Tuners be able to do the computer work or does the whole thing need to be sent off/replaced?. I've rebuilt a few engines It's just this computer stuff that gets kinda hayzey. If I am deleting the AMF is there another Gen IV block that would work for this application? Screw it and get a 6.0 and stroke it?
I have a 2016 Crew Cab Silverado 4x4 that I bought new last summer. I have noticed that recently when the active fuel management switches from 4 to 8 cylinders that there is a loud (loud enough to hear it with the windows up, A/C and radio on) squeak like noise that comes from the truck. It makes this noise every time it switches from 4 to 8, no matter what the speed.
I don't remember it doing this until recently. I've googled active fuel management noise, active fuel management squeak and tons on other combinations, but haven't gotten any results.
I wanted to check on here and see what you guys thought before looking like a dumb ass and taking it back to the dealership.
I have a 2007 Tahoe 5.3L LMG (AFM) 4x4 LTZ. Truck has 190k on it. The other day it developed a very rough idle and flashing CEL. Prior to this there was no indication of a problem. Scanner says misfire cylinder 1. I do all of my testing that I can do such as spark plugs, wires, verify injector signal with noid light etc. End up using compression tester to find 0 PSI on #1 and other cylinders at 110-120 PSI. During one of the compression test on #1 the gauge jumped to 60 PSI then next cycle dropped to 0 (unsure how to interpret that). Took truck to local shop and despite my efforts to inform them of the AFM lifter issues that could be causing this loss of compression they basically said that based on the 190k mileage i should only consider replacing with long block rather than repair the heads. They then quote $6600 for Jasper reman and install.
So to my question... Are they right the I should do a reman long block or consider repairing heads? I know I have been lucky to get that kind of mileage without issue but just wondering what others would do. Truck is in great condition otherwise and I plan to keep for the foreseeable future. Thanks for your help.
I have a 2010 Chevrolet Tahoe PPV with a 5.3L LMG and a 6L80 Trans (MYC) looking to drop in a 6.2L L9H. As far as I understand it is a direct swap. Would I run in to any issues or codes as far as the L9H not having AFM/DOD? I plan on using the 5.3L PCM and having it re flashed to work with the 6.2
Or do I look for a L94 that has FlexFuel, VVT, AFM like the LMG does?
For the LTZ 5.3 vs 6.2...looking at the 4dr 6.5bed...the mpg it shows on the window seems a little low for using AFM...what are your actual numbers you get? We'll say without towing, and with if ya got it...say you just bought it and went on the freeway for a few hundred miles and AFM was on, theres no way to get 18-20mpg, is there?
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