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I'm currently working on a rotary engine in my university. We received a 13B DEI from 1989 in the lab but the problem is the meetering oil pump. I have the Motec M84 as an ECU, but I don't really understand how to handle the electronic meetering oil pump with it.
I'd be very happy to get some expertise from you guys
If the Motec supports it (and you have the available I/O) it may be able to control the OMP directly for you. This is something you should check for in the manual, as not all ECUs support it. Alternatively, especially if this is going to be a racecar, you could just add premix to the fuel and block-off or ignore the OMP.
I've also developed a controller that will let you command the OMP with a generic PWM output from your ECU, which will hopefully be available for purchase soon. Waiting on feedback from a few early adopters before I start officially offering them.
So our goal is to put the engine on a test bench at the university lab and take measurements of the heat losses in the combustion chamber.
Would you have any datasheet about the OMP ? Cause I can't find any ... I have auxiliaries ports on my ECU, if I have a datasheet I could try to figure out a way to handle it with those auxiliaries.
On the earlier motors, the OMP was controlled by a linkage from the throttle, if it makes it easier you could get one of those and run it with a servo motor. If it wouldn't affect your experiment as a last resort you could premix oil into your fuel.
There is info about the OMP in the factory service manual. They're available at Foxed.ca
I also have the relevant pages saved, and I can upload them here later when I'm home from work.
One thing is that the factory ECU drives the stepper motor in the OMP in unipolar mode, whereas most aftermarket ECUs (and also my controller) drive it in bipolar. I've noticed no issues with speed or accuracy doing it this way.
So like I mentioned, the stock ECU drives it in unipolar mode. Those center B+ connections are not used in a bipolar arrangement, which is how most ECUs offer stepper control. You'll need four stepper outputs.
Then, the three pin connector is for the feedback sensor. I'm not sure whether the stock ECU uses this for PID control or just for error-detection, but it's a simple 0-5V signal telling you the position of the stepper motor. It's physically limited on S5 models around 18% minimum and 85% maximum.
Also, here is a map of the stock duty logged from an S6 ECU (should be perfectly fine for S5 too):
That was uploaded by a member who is hasn't been active in awhile, vl_alexander. The top row is extrapolated. If you can only control it based on one variable, I would control it based on MAP and just use the 8000 column values. This is basically how the S4 and earlier mechanical pumps did it.
Do you have any idea of the units for the X and Y-axis ? I don't really get what it represents
The Y-Axis is manifold pressure in kPa. So since yours is naturally aspirated, you only need the values up to 100.
The X-axis is engine speed (RPM)
The value in the table (for a given MAP and engine speed) is the percentage position of the sensor on the OMP, as 0-100%. Like I said, the OMP is physically limited to a minimum 18 and a maximum 85, as measured using the 0-5V feedback sensor.
04-11-23, 08:16 AM
