Long story short... I'm retaining the RX8 ECU with my engine swap. The RX8 throttle body will be kept and I'm adding the 8's trigger wheel to my engine so the 8's ECU will control idle, cruise control, maybe traction control, a/c, fans, and w/e else. In doing so I think I'll need to keep the ECU out of limp mode to prevent it from limiting the throttle body. It can have all the diagnostic codes it wants as long as I keep it out of limp mode. Most of the sensors I can either simulate or they won't cause limp-mode but I bet an oil pump error would.

Questions about using the Cobb.
Can I adjust idle speed?
Can I eliminate the oil pump?

I thought maybe Cobb would add that feature for those who want to run premix and eliminate the pump but I don't know for sure. Anyone know?

 

Idle speed can be adjusted. Oil pump cannot be cut off via Cobb.

 

Is there another way to disable it?

 

I haven't seen any reference with a method of disabling the OMP, though it -may- be possible. I seem to remember MM disabling it for one of his engines?

 

I know there is a way to disable the cel's associated with the omp, I was going to have him do it for my car.

 

I haven't verified that a missing pump causes limp mode. It's unlikely I'd find someone to test the theory but it should. I can't imagine Mazda's programmers allowing someone to rev the engine with a pump error.

The sooner I find a trigger wheel the sooner I'll know. I left mine attached to the engine when I sold it.

 

Yes, disconnecting the OMP will force the ECU into limp mode. This has been proven time and again.

 

You cannot disable the OMP with the Cobb, not having the OMP plugged in will cause limp mode, no way around that if you are using the stock ECU.

 

Ok. I'll look into emulating it. I know it's a stepper motor with position feedback. An MCU can be programed to count the pulses and output a proportionate voltage. Guess I start by opening the pump and see how it works.

 

That sounds like a great idea .

 

Is this something you guys need for race builds running premix or do you just leave the pumps plugged in?

 

When the Renesis was originally first being used for racing, race teams experimented with removing the OMP. The engines blew up REALLY fast. This is where we discovered that the OMP's primary purpose is to lubricate and cool the side seals, not the apex seals. The side seals weren't a problem for the prior generation 13bs due to the exhaust port location difference. Premix alone can't make up the difference.

 

You can plug in an omp and have it tied up somewhere out of sight ................................

 

I didn't know that. So the only use of an emulator would be for engine swaps retaining the stock ECU.

Thanks for the answers.

 

yep! ECU has no way of knowing if the metering pump is bolted to the engine or the fender, hint hint

 

I knew that much. That's a last resort.

A friend of mine is coding up a PIC to output the ESS signal so I can bench-test this ECU out of the car and see what else might cripple the throttle. There's another sensor (SPST switch) on one of the intake tumblers. Once the solenoid is activated and the vacuum motor opens the valve, it tells the ECU it's open. I might be able to fake that with just a relay so long as the ECU doesn't complain about it opening to fast. If those activation points are adjustable with the AP then maybe I can just set the activation point higher then redline (~7k).

 

There are quite a few different ECU limp modes. Another one I ran into was losing signal to the throttle position sensor. Fixes the RPM at 3,000 and disables the throttle input. Unknown how this might play with your swap.