DOD and efficiency?
Joined: May 2004
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From: Halfway back on the Highway to Hell...again!
None for the most part unless you're driving long distances, on flat ground 98% of the time. Other than that, it's just a "lifter-waiting-to-fail" scenario.
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From: Central Cal.
My wife's 08 Suburban has it, and there is a display that tells whether it's running on 4 or 8. It is RARELY on 4....
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From: PDX-OR-USA
Anecdotal comment: I had a rental 2019 Tahoe that I drove from Oregon to Georgia and back in 1 week.., On the mid west part of I80 I was getting 25 on this along flat stretches and the engine was staying in 4-cyl mode all the time.. Only bumping down when I'd pass or hit a short hard grade. When the engine was in V8 mode I was getting 18-22.. My overall mileage for the trip was 23.5mpg.. I thought that was kinda cool.. 
I was hauling a engine in the back of it.. About 375 lbs plus camping gear.. prob another 75 lbs.
I was hauling a engine in the back of it.. About 375 lbs plus camping gear.. prob another 75 lbs.
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From: Central Cal.
or Yeah, the newer ones cut out a BUNCH of cylinders at times. I bet it was on only about 2 or 3 cylinders when getting 25mpg. Was it a 6.2 or 5.3?
Anecdotal comment: I had a rental 2019 Tahoe that I drove from Oregon to Georgia and back in 1 week.., On the mid west part of I80 I was getting 25 on this along flat stretches and the engine was staying in 4-cyl mode all the time.. Only bumping down when I'd pass or hit a short hard grade. When the engine was in V8 mode I was getting 18-22.. My overall mileage for the trip was 23.5mpg.. I thought that was kinda cool..
I was hauling a engine in the back of it.. About 375 lbs plus camping gear.. prob another 75 lbs.
I was hauling a engine in the back of it.. About 375 lbs plus camping gear.. prob another 75 lbs.
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Was a 5.3, the dash only said 8 or 4 so no idea if it could do any other combinations, the switchover was totally invisible.. couldn't even feel it.. And I averaged 85 from the rockies to Atlanta.. 
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From: Central Cal.
OK, it might be just the 6.2's that cut out more, and maybe only the last year or two. You did pretty well!
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Yea for a big honking rig like that I thought that was pretty good..
MY 53 swap already has me impressed on my Jeep Wrangler, My first fill-up I'm at 22. < 200 miles on it..
(L33 with L59 flex fuel manifold and external accessories.. )
MY 53 swap already has me impressed on my Jeep Wrangler, My first fill-up I'm at 22. < 200 miles on it..
(L33 with L59 flex fuel manifold and external accessories.. )
Joined: May 2004
Posts: 1,593
Likes: 267
From: Halfway back on the Highway to Hell...again!
The common reason for failure is the VLOM, valve lifter oil manifold. Basically the valley cover on AFM engines. But when a lifter goes down, it'll let you know it.
You keepa knockin but you can't come in......and....knockin on Heavens door
The new 2020+ engines now have all 16 lifters that are AFM. The ECM can choose whatever cylinder it wants to shut down and will continuously alternate cylinders so as not to always using the same 4 cylinders.
These new engines suck. So many different variables with fuel lines, injectors, etc.
You keepa knockin but you can't come in......and....knockin on Heavens door
The new 2020+ engines now have all 16 lifters that are AFM. The ECM can choose whatever cylinder it wants to shut down and will continuously alternate cylinders so as not to always using the same 4 cylinders.
These new engines suck. So many different variables with fuel lines, injectors, etc.
The common reason for failure is the VLOM, valve lifter oil manifold. Basically the valley cover on AFM engines. But when a lifter goes down, it'll let you know it.
You keepa knockin but you can't come in......and....knockin on Heavens door
The new 2020+ engines now have all 16 lifters that are AFM. The ECM can choose whatever cylinder it wants to shut down and will continuously alternate cylinders so as not to always using the same 4 cylinders.
These new engines suck. So many different variables with fuel lines, injectors, etc.
You keepa knockin but you can't come in......and....knockin on Heavens door
The new 2020+ engines now have all 16 lifters that are AFM. The ECM can choose whatever cylinder it wants to shut down and will continuously alternate cylinders so as not to always using the same 4 cylinders.
These new engines suck. So many different variables with fuel lines, injectors, etc.
I lost a DOD lifter in my 07 Yukon. Cost me about 800.00 to convert to non-dod camshaft and programming, and about 40hrs of my time or more. I think I saw about a 1 mpg difference, not to mention increased oil usage while on 4 cylinders. So really how much money did that 1mpg cost me on the back end?
If this was a regular-persons vehicle that has to take to to a shop or dealer - the truck would be pretty much a total loss, over a fu*cking lifter b/c the shop would want to put a reman engine engine which after fixing my truck myself - I kind of u/s why.
If this was a regular-persons vehicle that has to take to to a shop or dealer - the truck would be pretty much a total loss, over a fu*cking lifter b/c the shop would want to put a reman engine engine which after fixing my truck myself - I kind of u/s why.
Joined: May 2004
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From: Halfway back on the Highway to Hell...again!
On my 2013 truck (LC9) I turned AFM off 6 months after I got it. MPG impact was negligible.
Happy to say 8 years later that it burns no oil, no lifters knocking, or any issues.
Regularly tow 5K plus with it. (Very grateful for the 6L80)
Happy to say 8 years later that it burns no oil, no lifters knocking, or any issues.
Regularly tow 5K plus with it. (Very grateful for the 6L80)
