Homemade vp44 and ECM arduino project update #4

[Great work!]

So I had lots of very hot weather to test the VP44 project. On a 103 degree day the controller hit 175 sitting in traffic with AC on and 120s while moving along. No problems it never missed a beat I'm happy about that I was a bit worried. 

 

I got one of those piezoelectric sensors that clamps around the injection line and had to build something called a charge amplifier  and insulate it from ground and use a shielded cable to get rid of all the noise so I could see anything reasonable. 

 

Timing wise things didn't add up. I finally got frustrated and pulled #1 injector and used a dial pointer to mark TDC and made a pointer mounted to an oil pan bolt. Next I connected a meter to the cam sensor and crank sensor and very slowly turned the crank and confirmed my timing waveform (I drew it on a piece of tape on the balancer😏) with what I had with it running and found a 10 degree error.

 

That explains why my timing just wasn't adding up. It was actually close by coincidence. What I found was that engine has too rotate about 10 degrees from the moment the inj valve seats because the cam donut has a very gentle ramp at first, the plungers have to move about 10 degrees (crank) to reach the pop off pressure of the injector. I can see the pop off with the piezoelectric sensor.

 

Then there is the line delay from pump to injector it's how long the pulse takes to get there it's based on the speed of sound through diesel which is 1357 meters/second. The lines are 32 inches long. That's 0.81 meters.

So that's 1/1357 = .737 mS to go 1 meter X 0.81 equals .597 mS delay.

 

At 1000 rpm the crank rotates 6000 degrees in 1 second so 6 degrees every millisecond.  So 6 X .597 = 3.6 degrees at 1000 rpm that same delay equals 10.8 deg at 3000 rpm.

 

I have adjusted the way the controller calculates timing now. I suspect that the line delay, which is determined by line length is sent to the vp from the ECM in one of the CAN bus messages. But my ECM is toast.

 

BTW, I figured out another pair of bytes in one of the CAN messages from the pump. It's the delay in microseconds from the time the injection solenoid current is shut off until the time fuel actually stops injecting. It's runs around 760 uS. On mine.

 

 

Edited August 27, 2023 by Great work!
More info

[Mopar1973Man]

Just keep in mind pop pressure affects timing as well. If popped at 310 bar you should be right on. For every 10 bar plus or minus is roughly 2 degrees I've figured in tuning. Just a tidbit to pass along to help you out.

[ICU_24VNUT]

If you want a NEW ECM I'll chip in. Still had plans to make my own VP44 also. But sense your already going threw the trouble it would be cool to get a KIT or something if you decide to sell kits + instructions.  I'm thinking of making a stroker vp44. Unlike the dragon or anything I'll just make my own housings with larger fuel flow. Have a idea to make it less choppy down low / while towimg unlike my multipler idea for the CP3'S.. but I'm still just working. Need to figure out the software side of things on my end for work... and something else on my end... but I'd love to make something and walk the CP3 trucks still...

Edited March 28 by ICU_24VNUT

[Great work!]

I measure about 10mm of stroke on my standard VP. I don't have any way to measure it exactly. 

 

I've been quietly working on a new project called ECM Explorer. I have PCBs already and connectors. But I have been designing a case and mounting plate for it. I'm using FreeCad, Slic3r and a 3D printer and I have never done anything like it. It has been a real learning experience.  The mount will be Lazer cut aluminum probable Xometry or Send cut Send.

 

I'll be happy to have all my guages working again. The code is a basket case of functions from other projects right now and I still need to stuff a board and get any bugs out of it.

 

I'm going to have to rig up my VP with switches to cut back and forth and parallel run with my own and stock PSG so I can finish decoding the protocol between it and the ECU.

 

I have no Original ECU that works that makes things a little tricky. I did record some sessions a long time ago as the ECM was starting to die. When I get things farther along I'm going to open source it on GitHub, that will be another learning experience. 

[ICU_24VNUT]

You can still buy the ECM there's remans out there. You could PM me a shipping address and the next time I have some spare cash like in a couple of checks I'll send you a new ECM.

I need to pay off my mechanic and buy some stuff for my truck still... but after I get a DOR front end, tires, and go threw steering and suspension + realignment ill send you one around that time after I get some cash. Especially if it'll really help. 

 

[Mopar1973Man]

Check out @Auto Computer Specialist for replacement ECM. There isnt any new ECMs only reman'ed.