If the OMP wiring is damaged, does the OMP continue to work normally as a mechanical pump but obviously not communicating with the ECU OR does it somehow get signals through the wiring on when to pump/inject?


I'm wondering because a while back a broken belt cut through my OMP wiring. Car went into limp mode due to the lack of signals to the ECU, but I'm curious if it still was pumping oil as always???

Thanks for any insights.

 

Yes, electrical signals from the ECU control pumping volume.

 

To continue from the post above, No, its not pumping. Why not just fix the wires???

 

yes it pumps, at minimum volume.

 

I have a replacement pump that I've hooked to the harness, that took it out of limp mode and I'm using premix for now. From old posts, I copied the idea of hanging the new pump and plugging it in to allow driving.

I had considered trying to splice the wiring from the replacement pump, but have not attempted it.

So, some minimal pumping, that makes sense given the mechanical hook up.

thanks

 

The OMP is driven off a gear. At each engine speed there is a minimum amount of oil flow due to the driving action of the gear. Movement of the plunger increases the oil flow from that minimum,. On the older rotaries (pre 1989), the plunger's function was controlled by a simple actuator rod connected to the throttle. On 1989 through 2008, a stepper motor replaced the lever and could control based on measured airflow or manifold pressure, as well as other factors like water temperature.

The ECU can judge whether the stepper motor has failed or whether the plunger isn't moving based on the position sensor in the OMP. Regardless of where it is stuck, the ECU is pre programmed to limit engine load to what is possible at the minimum flow rate for each engine speed.

 

So, the ECU is reading the signals from the OMP that is plugged in, but Not installed. I'm guessing the old OMP is simply pumping a minimum amount of oil since it doesn't know the airflow, rpm or manifold pressure. Still should premix then to be safe.

 

You overrode the limp mode basically, so yes you need to premix. If you plug in the bad one and go back into limp mode, your engine will still be safe, because it won't be able to exceed engine load where the apex seal can over heat due to insufficient lubrication.