DFM disabler released

[Antonm]

Post edit:
Looks like Holley (Range Technology is one of Holley's brands) got bought by one of those investment firms/ capital groups (Sentinel Capital Partners in this case) back in 2018.

When that happens it usually means the downfall of the company and it products because the focus goes from making a quality product, to making money. Because the investment company guys aren't car guys, they're money guys.
...

 

[fondupot]

FWIW, I haven't noticed any difference in deceleration since installing the Range module. Is the 0-cylinder decel/coast feature really activating DFM lifters to close off valves? or is it simply cutting off fuel supply to those cylinders? Big difference I should say.

 

[Kpwweb]

So let me get this straight,,,you think that a piston going to the top of the cylinder with an open exhaust valve every other engine rotation, which will allow the air/gasses in the cylinder to escape out the exhaust system, will provide the same resistance as having both valves closed (because DFM collapsed the lifters) so that every time the piston goes to the top of the cylinder it must compress those gases? Do I have that right?

In a V8, in any given rotation of the crankshaft, with the lifters locked, there would be four cylinders doing a compression stroke and four cylinders on an exhaust stroke when the piston came to the top of the cylinder, so only four of the cylinders would be causing resistance to rotation, or braking force, for every crankshaft rotation. Now unlock the lifters, and all eight cylinders would be compressing air/ gases causes resistance to rotation, or braking force, every time they came to the top of the cylinder.

The whole restricting the exhaust thing is the same principle (different method, but same principle) used the ever popular "Jake Brake" on diesels, seems to help slow them down.
...

Obviously everything you say depends on cam timing, temperatures, air in the cylinders, etc. But I’m not as “smart” as you are.

The thing is, you will believe what you believe, I will believe what I believe. The Range gives me a small glimmer of hope to modify my vehicle without resorting to a full tune—especially since GM has locked down the ECM. My last Tahoe I had tuned and got 125k out of before trading it on this one. Dealership still got $25k for it. It was glorious.

Even if DFM is turned off half the time, which we can debate until the end of time, that would still equate to longer life than having DFM engaged all the time. I’ll take that opportunity as a “dumb” consumer. You can tool around in your DFM rig, its a free country. Most people don’t notice. I do.

I do wish someone would come out with a tunable piggyback unit—it just might be you? You could be the driving force for good, right to repair…..

 

[Antonm]

Even if DFM is turned off half the time, which we can debate until the end of time, that would still equate to longer life than having DFM engaged all the time.

While never having cylinder deactivation would be the best, I suppose having less of it is at least somewhat better.

Still wonder why they wouldn’t ( maybe couldn’t) just turn the whole dang system off, they even named the device “DFM disabler”

Holley ( the parent company of Range Tech) sent me an email listing all the hoops I needed to jump through to return the device , things like “must be in the original packaging” was in there, a restocking fee and it has to pass their inspection before they’ll consider refunding ( of course if it doesn’t pass their inspection then you’re just SOL).

I posted screenshots of the emails but edited the post because it didn’t matter, then I looked closer and figured out Holley isn’t a car enthusiast company anymore, they’re owned by an investment capital company, so car guys no longer make the decisions, money guys do, so it makes sense that they’re making crap products now.
…

 

[Marky Dissod]

Please bear with me for a few stops on a train of thought ...

Maybe back when GM's Gen4 V8s first debuted, 'disabling' cylinder (valve) deactivation was easy and simple: deselect what tuners call a 'switch' / 'flag'.
The most basic tuning experience (after switches and flags) involves changing temps / RpMs / road speeds / throttle %age / MAP reading
so that, even if a feature's switch / flag remains 'enabled' - or is simply unavailable! -
by specifying an unlikely or impossible temp / RpM / road speed / MAP reading, or an impossible combination of those,
a feature can remain enabled and yet still never activate.

Example: by raising the 'CAGS Enable' coolant temp threshold over 125C / 257F, that T56 will never force a 1st-to-4th ever again.
If something odd happens to the coolant temp circuit,
change the 'Speed Threshold to Disable CAGS' to 1MpH (or 155MpH), then
change the 'Speed Threshold to Enable CAGS' to 0MpH (or 154MpH), and CAGS is effectively disabled.

Two more stops ...

 

[Marky Dissod]

Some of you know that the plug-ins that disable auto-stop start and or cylinder valve deactivation
are not tunes-in-a-can; rather, they fool the ecm, either by feeding it false info, or hiding something from the ecm.
Since several conditions (temps / RpMs / road speeds / throttle %age / MAP reading) have to be met for cylinder deactivation to be allowed,
and ALL of them must be in effect (each within a narrow permissible window) at once for cylinder deactivation to be active,
if any one of them is missing or false, the ecm will not activate cylinder deactivation even if it is enabled.

 

[Marky Dissod]

I've only seen a GM Gen5 V8's tunable parameters once, and that was before 2017,
when GM started using much more complex encryptions (that's why it takes a few years to 'crack' an ecm / tcm;
ifyouarenotfluentinalanguageit'snoteasytodecipherwherewordsbeginandendandthat'safterdefeatingtheencryptions -
oh and ecm / tcm code is written in hexadecimal).
It is increasingly possible that there are more parameters that enable and/or activate cylinder deactivation,
or worse yet, some combination of more parameters ...

In other words, I'm not shocked that disabling cylinder deactivation is - for the time being -
impossible until the vehicle gets over 40MpH, or that it cannot be completely disabled when the TPS% = 0.