AFM / DOD Delete

[2001 TX Tahoe]

I’ve read some about this topic but need some educating. I understand there are components (lifters?) that are responsible for switching between V4 and V8 modes. I've also read there is an OBD II module to override this so that it stays in V8 mode. Also read this is just a band-aid. So, am I understanding this correctly? Is there one or are there more modules? Is there is specific one that is recommended? Or big picture, is this recommended at all? And if it the lifters are no longer functioning, how can they still fail, i.e. how is it just a band-aid fix? Or is something else failing? For reference, I have a 2016 Yukon, 5.3L, 99,000 miles, no motor issues. Just trying to get in front of a potential problem.

 

[Marky Dissod]

Merely disabling cylinder deactivation / V4 mode ...
You can buy a glaiyd plug in type thingy that just plugs into your OBD2 port.
So long as it stays plugged in, permanent V8 mode. Pull it off, V4 mode becomes available again til plugged back in.

A far better method of disabling V4 mode - worth every extra penny - is to get the ecm tuned.
Besides disabling V4 mode, several other things get addressed.
The end result can include more MpG, more smiles per gallon, more durability / longevity, additional functionality ...
Ask the tuner what they can and cannot do, then check back with us to see if our bs detectors go off.
BlackBear tuning is highly recommended here.
There are several other highly respected tuners who have maintained stellar reputations for many years (see my sig).

However ...

 

[Marky Dissod]

Physically deleting cylinder deactivation hardware ... (We are NOT discussing Cadillac's V8-6-4!)
Before V4 mode, hydraulic lifters simply did their simple job, well, for 250,000 miles or more in many cases.
In other words, they were very well designed to reliably do one thing.

Then came V4 mode in the late naughties.
8 of the simple one-mode lifters (out of 16 total) had to be replaced with two-mode lifters.
These lifters respond to changes in oil pressure directed by a Variable Oil Lifter Manifold Assembly.
In V8 mode, they are swollen. In V4 mode they go flaccid.
The extra hardware that allows this variable modality was neither designed nor materially specified to be as robust as the one-mode lifter.
After about 15 years, V4 mode lifters have earned (?) notoriety for failing far more often than one-mode lifters.
(They also don't like excessively leadfooted drivers who spend too much time at very high RpMs.)
Changing oil and filter more often than GM recommends helps them last longer, but they'll just never last as long as their simpler ancestors.

Simply put, the long-term solution is to remove & replace the dual-mode lifters with one mode lifters.
A few other things need replacing as well, like that Variable Oil Lifter Manifold Assembly; it gets replaced by something far simpler as well.
The end result is a V8 that will never physically impersonate a V4 ever again.

 

[Marky Dissod]

For reference, I have a 2016 Yukon, 5.3L, 99,000 miles, no motor issues ... YET ...
Just trying to get in front of a potential problem.

Disabling Engine Half@$$ (plug-in or tune) will delay the failure of the two-mode lifters.
It also helps to change your oil more often than GM recommends, and to use a larger oil filter.
Same goes for your air filter. Keeping things clean is CRUCIAL.
However, the two-mode lifters can still eventually fail, even with Engine Half@$$ disabled.

That's THE major reason why people do lazy cylinder hardware deletes.
To be clear: there have been enough two-mode lifter failures in engines with Engine Half@$$ disabled,
that a preemptive lazy cylinder hardware delete is strongly recommended for anyone with long-term plans.

Long story short:
everyone should disable Engine Half@$$ (or Cylinder Confusion) at first opportunity to lower the odds of a lazy cylinder hardware failure.
To permanently avoid any possible failure, delete lazy cylinder hardware at first convenience.

 

[2001 TX Tahoe]

Disabling V4 mode (plug-in or tune) will delay the failure of the two-mode lifters.
It also helps to change your oil more often than GM recommends, and to use a larger oil filter.
Same goes for your air filter. Keeping things clean is CRUCIAL.
However, the two-mode lifters can still eventually fail, even with V4 mode disabled.

That's THE major reason why people do V4 mode hardware deletes.
To be clear: there have been enough two-mode lifter failures in engines with V4 mode disabled,
that a preemptive V4 mode hardware delete is strongly recommended for anyone with long-term plans to keep it.

Long story short:
everyone should disable cylinder deactivation at their first opportunity to lower the odds of a V4 mode hardware failure.
To permanently avoid any possible failure, delete V4 mode hardware at first convenience.

This is all very helpful. Thank you.

Ballpark, what should an ECM tune cost from a reputable tuner?

Deleting the hardware... is this a "tear the engine down" type of mod? How expensive and complex?

Finally, what happens when the dual mode lifters fail?

 

[SpyShops212]

Just drive in manual 9

 

[Marky Dissod]

Ballpark, what should an ECM tune cost from a reputable tuner?
Deleting the hardware ... is this a "tear the engine down" type of mod?
How expensive and complex?
Finally, what happens when the dual mode lifters fail?

Someone needs to answer these questions in better detail than I.
I don't know as much about Gen 5 direct injection V8s as I do about Gen 3 & Gen 4 V8s.

 

[tom3]

One of these springs lets go and it all gets bad real quick.

 

[tom3]

As opposed to a standard hydraulic lifter:

 

[Marky Dissod]

If I'd seen pics like these in '05, I'd've been looking for how to defeat this folly in '06.

 

[clogan2]

Just drive in manual 9

Or, for a '16 model, use M5.

 

[MobileHomie]

This is all very helpful. Thank you.

Ballpark, what should an ECM tune cost from a reputable tuner?

Deleting the hardware... is this a "tear the engine down" type of mod? How expensive and complex?

Finally, what happens when the dual mode lifters fail?

OP, I have a 2017 Yukon Denali with 6.2L and an 8 speed.
I am going to answer your last question first. What happens when a lifter fails? Within moments the pushrod will bend. If the engine continues to run it will destroy the cam shaft very quickly putting metal shavings in the crank case requiring a complete tear down and rebuild of the engine IMHO.

In my opinion the tune or dongle disabler is a stop gap measure. I did install a Range dongle when I bought the rig with 32K miles on it and have no idea what a tune would cost.

At 62K miles a light tick made itself known of a morning, I believe this was the lifter failure, moments later the tick got louder, bent pushrod. I drove it two miles home and shut it off.

I made the decision to delete the AFM cam and lifters, I called them "tender bits", and a high performance engine needs a solid valvetrain.

Anyway I contacted a speed shop in the nearest city to me, Reno, trailered it there and had them do the deed. The list of parts is quite extensive including stage I BTR cam/lifters VLOM, and oil pump. They pulled the engine from the chassis for this job. Dyno graph says 352 HP at the back tires. The whole thing was about $6,200.

Come to think of it, the lifter failure was Feb 19 last year. It took till April to get it in the shop and I have been very happy with the results, sill puts a smile on my face a year later. MPG wise, it gets 19.5 with the cruise set at 87 mph, not bad for a full size SUV.

 

[Marky Dissod]

MpG wise, it gets 19.5 with the cruise set at 87MpH, not bad for a full size SUV.

19.5MpG, after deleting Engine Half@$$.
What MpG did it get when it had Engine Half@$$?

 

[MrMonte]

I had my AFM tuned out for 30K+ miles & still had an AFM lifter failure on my 2018 Yukon Denali. I have 6k miles on my AFM delete & went from 20 to 21+ mpg with mixed driving. My 50 mile round trip to work nets me 25-27mpg depending on how may lights I hit. The extra power thru the whole rpm range is a big plus. I did the AFM delete cam swap myself.

 

[MobileHomie]

19.5MpG, after deleting the DOD. What MpG did it get when it had DOD?

There was no noticeable difference. Bear in mind, I have a lead foot and like fast cars and guns.
My cite of 19.5 mpg is for a port to port trip to Reno and back, cruise set at 87 mph, 320 miles, no idle time or stop and go traffic.
One of the computer generated "trip meters" was set in January of 2022 and shows an overall mileage of 11,318, 15.4 mpg and average speed of 29 mph.

 

[Marky Dissod]

That's the other problem with Engine Half@$$.
The amount of fuel Engine Half@$$ saves does not justify its existence, even before it fails.

Plus Engine Half@$$ can increase oil consumption, and make it happen sooner.

 

[jets]

16 Denali 6.2 8-Speed. I had a tune and AFM disabled recently. It went from 290HP/308TQ to 328HP/339TQ at the wheels. I had them tune it with a more aggressive throttle response and the truck runs so much better. In the future I plan to delete the lifters, install a bigger cam and headers while it's opened up. My shop said when I decide to do that it'll cost around $7500CAD/$5600 USD. Between this and the lowered Belltech springs/struts/magdelete it's a total transformation.

 

[hillstrubl]

I just picked up a 2011 Tahoe (5.3) and I'd like to immediately do the DoD delete, can this be done in phases? Software first, then change the cam, etc. Does anybody know of a shop in the Philly area with experience doing this?

 

[Marky Dissod]

I just picked up a 2011 Tahoe ... I'd like to immediately do the Engine Half@$$ delete.
Can this be done in phases? Software first, then change the cam, etc.
Does anybody know of a shop in the Philly area with experience doing this?

Must disable the software before deleting the hardware, or the ecm starts whining about an Engine Half@$$ malfunction.

 

[blondie70]

If the stock cam is not damaged...engine running good..........can just the lifters all be replaced with stock ones ? The push rods would need replacing also ?? thanks