DFM disabler

[Stormin08]

I actually purchased from BANKS a sensor and the specific hardware that attaches to the oil filter area from Improved Racing. I will provide the links below for you if you were interested in adding these to your rig. You would need an extension cable also to ensure your connection is long enough to reach from the oil filter hardware to the I-dash.
I keep an eye on my oil pressure along with many others. My pressure ranges between 65 to 105psi. However I believe my pressure shows higher because I have the Banks sensor directly attached to the oil filter spacer from Improved Racing. It is unfortunate the I-dash doesn't have the PID.

Pressure Sensor for iDash DataMonster and Super Gauge [63085-15G] - Banks Power

Stainless steel pressure transducer with 1/8 NPT threads. In 4 PSIG ranges from 0-15 PSIG to 0-150PSIG. High accuracy and fast responding sensor. Plug and Play with Banks 4-CH Analog Module.

bankspower.com

Oil Filter Spacer for Recessed Filters, With Sensor Ports

New, revised design: Sensor ports are now offset for better clearance with recessed filters and acommodates longer sensor probes. Oil filter spacer designed for recessed filters. Features 2 x 1/8" NPT ports for sensors or turbo feed lines. Perfect for installing a sandwich plate on engines such...

www.improvedracing.com

i have looked at both, but like i mentioned...i would rather see what GM does...if they do. The 22 PSI engagement of the DFM has me intrigued.

 

[BigBlackie_'25TB]

i have looked at both, but like i mentioned...i would rather see what GM does...if they do. The 22 PSI engagement of the DFM has me intrigued.

I wanted to be able to see both oil pressure and temp, so I installed the oil filter sandwich plate, fluid temp sensor, and pressure sensor. As with the 22 PSI engagement...I have read something on that in the past before eventually moving to "electronically" disabling the DFM system with HP Tuners software. I believe the 22 PSI has to do with pressure that is needed for the lifter locking pins to operate (i.e., cylinder deactivation). So, if I remember correctly, the 22 PSI is only the pressure that "is needed", and does not necessarily mean once that PSI is reached that DFM activates. All in all, I think many variables are involved, i.e., requested torque, throttle position, delivered torque, RPM, etc., which determine whether the ECM commands which cylinders to deactivate. At least this is my understanding and recollection from what I read in the past.

 

[texanlife4]

Not to hijack a thread, but what is everyone's operating temp idle oil pressure?

 

[Mike Edwards]

I'll answer some more about the HP tuners stuff. At least in my 2020 silverado and in my wifes 24 tahoe, HP tuners doesn't have the PID for oil pressure addressed correctly so it reads 0 all the time in data logs. But I have the High country cluster with additional parameters from White Auto and Media that shows real oil pressure.

Not to hijack a thread, but what is everyone's operating temp idle oil pressure?

About 29psi.

About what triggers DFM. There are parameters that must be met to allow it to happen, but those aren't the same as what drives the demand for it to happen. HP tuners only gives access to bits of the tune that they can locate in the hexadecimal code. They haven't enabled much in the E90 in our trucks in relation to DFM. In the older 16-18 trucks with AFM, they had a lot of the qualifying parameters. Things like Oil temp, pressure, voltage, rpm, speed etc. Usually there is a high and a low for each that it must be in between to go into AFM.
From an 16-18 E92 ECM. This is what HPT has found. There's probably more.

The "oil pressure low" and "oil pressure high" are just the upper and lower bounds it's allowed to operate in, not that it always operates in that range.

I'm sure there are similar qualifying parameters in our trucks, but HP Tuners hasn't found them. They have only found the Disable RPM. Notice it's the same rpm in the E92 above.
Also notice the parameter on the right. Variable Torque. Nearly everything about the tune in our trucks is based on torque. When you press the accelerator pedal, you are "demanding" a torque value that is looked up in tables with vehicle speed, rpm etc. I'm sure there is demanded torque value at each rpm where it requires less than 8 cylinders to produce. So then as long as the other qualifiers of engine temp, oil pressure, temp etc are met it will go into dfm and pick the number of cylinders required to make the required torque.
From 19+ trucks E90 ECM.

 

[Mike Edwards]

i personally do not run one, as i typically manual shift my rig, and it rarely goes above 9th...
but this one has an interesting talk topic related to oil pressure....

AFM Disabler for GM Trucks | Active Fuel Management Disabler – Elycera

Plug-and-play GM AFM disabler for Chevy Silverado, GMC Sierra, Tahoe & Suburban. Protect your lifters, eliminate cylinder deactivation, and restore smooth V8 power.

elycera.com

I don’t fully buy that locking pin explanation. It’s one obscure little part of the dfm lifter, but not the only root cause.


The lifters are like shocks. Non dfm lifters are like .200” plunger/piston travel and dfm are probably more like .350”. The normal lifters gets full oil pressure all the time and only dampens high velocity movements. The dfm/afm lifter just has the ability to dump the pressure off the oil with a solenoid. Without pressure it can’t move the plunger (I guess this is where this locking pin thing disengages) and instead rides up and down the cam lobe without moving the pushrod. The spring on the top of the lifter should keep it on the lobe.

The springs break and the lifter body can bounce off the lobe eventually beating the roller. Or sometimes even with pressure, the have internal leakage enough that they bounce on the lobe. Sometimes the plunger gets cocked sideways in the lifters and it becomes solid and they bend a pushrod from coil bind. The last two can and does happen with non afm lifters too.

The clearances in the lifter are some of the tighest in the motor. And bits of trash in the oil can bind them up. So clean oil is important. But the whole spring mechanism that keeps the lifter on the lobe when it has no internal pressure, is junk imo.

This one broke the spring retainer. It went out of control and bound the plunger and bent a pushrod.

 

[BigBlackie_'25TB]

I don’t fully buy that locking pin explanation. It’s one obscure little part of the dfm lifter, but not the only root cause.


The lifters are like shocks. Non dfm lifters are like .200” plunger/piston travel and dfm are probably more like .350”. The normal lifters gets full oil pressure all the time and only dampens high velocity movements. The dfm/afm lifter just has the ability to dump the pressure off the oil with a solenoid. Without pressure it can’t move the plunger (I guess this is where this locking pin thing disengages) and instead rides up and down the cam lobe without moving the pushrod. The spring on the top of the lifter should keep it on the lobe.

The springs break and the lifter body can bounce off the lobe eventually beating the roller. Or sometimes even with pressure, the have internal leakage enough that they bounce on the lobe. Sometimes the plunger gets cocked sideways in the lifters and it becomes solid and they bend a pushrod from coil bind. The last two can and does happen with non afm lifters too.

The clearances in the lifter are some of the tighest in the motor. And bits of trash in the oil can bind them up. So clean oil is important. But the whole spring mechanism that keeps the lifter on the lobe when it has no internal pressure, is junk imo.

This one broke the spring retainer. It went out of control and bound the plunger and bent a pushrod.
View attachment 25905

Hey Mike! Glad to see ya back on here! I have done over 100 tunes on my rig so far! I'm learning and gittin'r dialed it!!

 

[BigBlackie_'25TB]

Not to hijack a thread, but what is everyone's operating temp idle oil pressure?

My operating oil pressure is between 50-65psi hot idle using 0w40.

 

[Stormin08]

i guess i just need to send my modules for an unlock....
every time i get a chance to get to it...i have another trip planned and dont have the days needed to send it.

really been more of a debate of offloading the whole rig and going back into a mid 80's rig....