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I managed to do a little testing last night. Don't know how helpful it'll be, but maybe it's a start.
The pump test runs just fine with the car on the ground. The engine doesn't need to be running, but it probably should be. The pump pulls a lot of power. It was showing over 13 amps at 100% duty cycle. The circuit has a 40 amp fuse. You can see it drags the batter voltage down from 12.3 to 11.3, That's with no load against the clutches too. The solenoid was open the entire time. The pressure reading would occasionally flicker to 64.0 BAR (928 psi) but that was just an occasional gap or error in the data. You can see this in the 0% image. It's not possible for there to be any pressure when the pump is off. I just got 'lucky' when I grabbed the screen.
I also ran the test for solenoid duty cycle, but it didn't show anything interesting. You can step it up and down in increments of 10% like you can with the motor.
I'll try to take the car out this weekend to log these parameters under real world conditions.
I have a USB oscilloscope, but I haven't learned how to use it yet. This might be a good excuse to finally do that.
I managed to do a little testing last night. Don't know how helpful it'll be, but maybe it's a start.
The pump test runs just fine with the car on the ground. The engine doesn't need to be running, but it probably should be. The pump pulls a lot of power. It was showing over 13 amps at 100% duty cycle. The circuit has a 40 amp fuse. You can see it drags the batter voltage down from 12.3 to 11.3, That's with no load against the clutches too. The solenoid was open the entire time. The pressure reading would occasionally flicker to 64.0 BAR (928 psi) but that was just an occasional gap or error in the data. You can see this in the 0% image. It's not possible for there to be any pressure when the pump is off. I just got 'lucky' when I grabbed the screen.
I also ran the test for solenoid duty cycle, but it didn't show anything interesting. You can step it up and down in increments of 10% like you can with the motor.
I'll try to take the car out this weekend to log these parameters under real world conditions.
I have a USB oscilloscope, but I haven't learned how to use it yet. This might be a good excuse to finally do that.
thank you! This helps a lot, I know what range of psi we are working with now.
is it possible they use the valve as a regulator? Or maybe that's what we would need to see under driving conditions.
im out in the shop now, my controller came on.
i noticed there seems to be a check valve on both lines. I was wondering why you need a special tool
to do the bleed procedure and now I know. I can't seem to find the tool but I should be able to make something from a hydraulic parts store.
of you happened to run a system bleed did you see what the valve was doing?
i will have to figure out what the system needs for the bleed and manually control it.
Lastly, is there a vehicle speed sensor on the diff?
it's in the car now. I didn't even look before but didn't see a sensor value on the images you posted
I don't see a speed sensor in the schematics or the parts diagrams. I think it just relies on wheel speed signals from the ABS system over the CAN bus.
Don't lean too hard on that 64 BAR measurement. I'd need to play with it some more, but it's possible that's just the maximum value you can get from a single byte of data. One byte of data can represent values from 0 to 255. So if it glitches and goes to 255 for a moment, then that could represent 64 BAR (255/4). That's not necessarily the max pressure the hydraulics can handle. It could be lower.
I didn't run the bleed procedure. It looks like it's meant to run with everything closed up, so it would probably be fine. But I didn't know that when I had everything hooked up last night.
Have you powered up the pump at all yet? I was surprised at how loud and high pitched it was with the engine off. It has an almost musical quality.
I don't see a speed sensor in the schematics or the parts diagrams. I think it just relies on wheel speed signals from the ABS system over the CAN bus.
Don't lean too hard on that 64 BAR measurement. I'd need to play with it some more, but it's possible that's just the maximum value you can get from a single byte of data. One byte of data can represent values from 0 to 255. So if it glitches and goes to 255 for a moment, then that could represent 64 BAR (255/4). That's not necessarily the max pressure the hydraulics can handle. It could be lower.
I didn't run the bleed procedure. It looks like it's meant to run with everything closed up, so it would probably be fine. But I didn't know that when I had everything hooked up last night.
Have you powered up the pump at all yet? I was surprised at how loud and high pitched it was with the engine off. It has an almost musical quality.
Havnt tried the pump but did hook up the solenoid to the PMW controller. It worked very well but I leave the Controller set at 70% (it closed at 50%) and the solenoid heated up very quickly.
not sure how else to run it unless I get a adjustable step down transformer and feed it a solid 6v ish to fine tune it.
@ 70% the voltage out put on the controller said 8.5V
it does work on both directions, I'm going to let it cool and do the same test with the other direction and see if it heats up the same
The rear differential clutch solenoid valve is an electro-hydraulic valve used to relieve pressure in the hydraulic system for safety reasons. When the valve is energized, the valve is closed and hydraulic pressure can be accumulated. When the valve is de-energized, the valve is open and it is not possible to build hydraulic pressure.
I still can't find anything about the damn operating pressures though.
I still can't find anything about the damn operating pressures though.
I wonder what I'm doing wrong to get it hot, must be on almost all the time during operation. Almost feel like I should modify it and put a mechanical relief in. If we were certain on operating pressure I could set it just above that.
Going to head to a hydraulic place and see what I can find. If I can find something to open the schrader valve on the lines it could be useful for most E diff owners that want to do their own fluids. From my understanding it's hit and miss if the dealer your at can do a proper fluid change and bleed on a e diff equipped C7. Could be cheap and in expensive way for a owner to do it properly.
they say it doesn't have to be done often but sealed system or not it's going to grab moisture and break down over time.
Just a quick update, I found the sweet spot on the solenoid with the Controller, had it closed for an hour and it was warm but never got hot.
Found a hose company i can check on Monday for parts to bleed the Ediff but I'm pretty sure you could wear some gloves and just depress the shredder valve while performing the bleed
I still can't find anything about the damn operating pressures though.
I got it working!
had to bleed the system with a screw driver (made a mess) but got it done!!
T'd in a mechanical gauge 0-1000
I only went to about 400psi in fear it maybe over doing it. The controller works perfect for it.
if you have a chance or had a chance I would love to know the max operating pressure, last price of the puzzle.
As soon as I know I'll order a pressure sensor from holly that has those pressures and get a finished copy.
Will need a relay for the pump motor controller, some fuses ect and to figure out where I want to mount the controls. May run the pump on the bench as well ti make sure it's not getting to hot ect.
Would be super easy to run this off paddles on a steering wheel for auto cross ect, go deep into the turn the threw the turn with it off and then hit it after your out of the turn or keep it locked for drag, drift and sweet burn outs.
I'll try to get the pressure reading, but I'm not sure if I can do that on the street anywhere. I was watching my ELSD display on the dash during a normal drive around town and it never got anywhere over 15%. I think I'm going to have to find some place to push it a LOT harder to really exercise the system.
I'll try to get the pressure reading, but I'm not sure if I can do that on the street anywhere. I was watching my ELSD display on the dash during a normal drive around town and it never got anywhere over 15%. I think I'm going to have to find some place to push it a LOT harder to really exercise the system.
if it does a bleed procedure does it let you read the PsI? I read it goes to 100% during a bleed. Or even if you had it @ 10-15% while reading the pressure we could multiply and figure out what 100% maybe
i am starting on a project and want to do the same thing, manually control the C7 ELSD. How did it work?
the controller I made worked on the bench but the car has been sitting for a few months. Hoping to work on it again soon just trying to get caught up with life lol
