When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am messing around with a 2007 5.3L LGM vin 0 engine.
In looking at the vlom wiring diagram, I am wondering if the computer can be tricked into thinking that the cylinder deactivation solenoids are there and working.
If I unplug the vlom connector and tie in 4 resistors (of the same resistance as the solenoids - 11 to 18 ohm) into the harness connector,
will that trick the computer into thinking the solenoids are there? Thus effectively de-activating the AFM system?
Like I mentioned, I am just messing around and trying to see if I can fool the computer. I guess I should say 'physically fool the computer'?
The solenoids (when activated) simply allow oil to flow through special passages in the vlom; this in effect collapse the lifter so the push rod will not open the valves; turning off the certain cylinders.
I know the ecm can be flashed and thanks for the offer. I will do that when I do my rebuild, and delete the AFM system.
I'm just wondering if it will work, and think this is a good place to get opinions.
So, if I get the AFM turned off (by having the ECU reprogrammed), does that tell the ECU that there 'isn't a situation that warrants activating the solenoids?
Or, what does 'flashing' the ECU to turn off the AFM actually do?
So, if I get the AFM turned off (by having the ECU reprogrammed), does that tell the ECU that there 'isn't a situation that warrants activating the solenoids?
Or, what does 'flashing' the ECU to turn off the AFM actually do?
You change the tune so the PCM thinks the engine does not have DOD/AFM so it never activates it.
This one is all about "what if" you.. So yea,, there are some missing functions....
Is there a doc somewhere that details the sequence of events for DOD ??
Don't know that Ive ever seen one, I never like the way GM implemented it
just the mechanical aspect seems hokey.. Never paid attention if it was pulling timing too or doing other "stuff"
If I understand it,, The Hemi's turn injectors off and just don't fire the cylinder..
From the original Northstar GM's implementation has had issues with engines doing valve cycle manipulation.
I'm going to just unplug it just to see what happens.
BUT, for a more permanent fix, I will have the ECU flashed to get rid of this system (electrically).
Unless you modify the block , install a different oil galley plate #1, change the lifters and cam shaft, you cannot remove the mechanical side of this system.
But if you kill the solenoid - you effectively kill the system....as long as the special lifters are NOT messed up......
Here is the 'mechanical' side of the system along with the solenoids. The solenoids #2 (electric) allow oil to flow to special oil ports (mechanical) in the special lifters #5. This special port 'kills' the hydraulic pressure in lifter and the lifter design does not allow the push rod to open the valves - thus the cylinder does not intake fuel/air, or exhaust anything. If the solenoid does not allow oil through the special ports, the lifter functions like a normal lifter.
Just disable it in the tune man. Might cost a few bucks, but this is the better answer. I've done it quite a few times for people, might cost you a hundred bucks for the creds, and someone that has the software, provided he don't charge you "extra"... That's the actual cost though to write a PCM in most cases. It takes literally 5 minutes, if you include the download and write times.
So the solenoids are normally closed,, and open to disable the cylinder ?
Or are they normal open and close cutting off the oil to disable the cylinder?
Never messed with one all the LS engines I've had hands on didn't have DOD..
Purely academic interest..
Normally closed (they have constant 12 volts BUT no ground - like the way an injector works)... They open (when the ECU applies a ground to them) to allow oil flow through the special ports shown in the drawing. This kills the lifters ability to hold hydraulic pressure in order to push on the push rod. No push on the push rod = no rocker arm movement = no valve opening. The valves of cylinder 1,7,4,6, do not open when the lifters are in this condition. No consumption of fuel/air = better fuel mileage.
The oil galley in a motor with this system is exactly the same as one without it - EXCEPT there are additional ports added to make the dod/afm system operate.
When the ECU is not activation the system, the solenoids are closed - no oil flows through the special ports, and the afm lifters receive oil from the normal oil passages just like the normal lifters do. The system is activated (by the ECU) in times of no load situations - such as cruising at highway speeds etc etc...
For me, I do not like it - and I will have it tuned out of my ECU - but for now, I just want to see what happens - and want to mess around with it.
This idea and technology is nothing new, and has been around for a while...
Just unplugging the connector makes the ecm think the afm is active and it kills 4 cylinders. I know because i installed a none afm engine in my car and just left the connector unplugged. I started it before tuning anything cause im an idiot and couldnt wait for my laptop to charge and it ran on only 4 cylinders. Laptop charged turned of afm and bam all 8 firing.
Ps runs like **** since the valves are still working but the fuel and coils arent there.
06-27-2019, 04:02 PM
AFM/vlom tricking computer? 
) 
