rotoman2

Does anybody know how the electric oil metering pump is wired on a S5? (I can't find this anywhere on Icemark's wiring diagrams or any links in the FQ's). I'm running a S5 engine in my 88 GXL S4. There are no connectors on the wiring harness of course, so I'm wondering if I can power the motor some other way. (Right now I'm running premix until I can determine how to connect the OMP). What comes off the unit is a 3 wire (Br-L-Y) connector and a 6 wire (W-Y:R-R/W:L-Br) connector. Seems like a lot of wires for a little motor.

It looks like there is the standard mechanical pump as well, and the electrical is just extra. Is that right?

steve84GS TII

Youll need the S5 ECU and harness to power the OMP.
The reason there are so many wires is because there are two parts to the OMP.The big plug leads to the stepper motor,which actuates the pump the same way the rod linkage does on older models.The position of the stepper is determined by RPM,throttle position,temperature,ect.
The smaller plug leads to the OMP position sensor.Its basically a device that reads the position of the stepper and tells the ECU if the OMP is in the right postion at the right time,during a given situation.

The mechanicals of the OMP are basically the same,but the housing is different to accept the electronic controls of the S5 unit.If your gonna run a S4 ECU with the S5 engine,youll have to change to an S4 front cover and mechanical OMP.Then,switch to an S4 throttle body so you can attach the mechanical S4 OMP pull rod.

rotoman2

O. K. thanks for the lowdown. I think I still would rather rig a controller than replace the front cover though.

rotoman2

still would be interested in an actual wiring diagram if anybody knows where to find one.

steve84GS TII

Since the signal is constantly changing based on stepper motor position itd be much easier to delete the limp mode of the ECU than to try and fool it into thinking the OMP is still there.
Yes,you could determine the resistance of the stepper motor and install resistors to make the ECU think the motor is still there,but how are you going to duplicate the ever changing output signal of the position sensor?A signal that changes not just in tune with throttle,but many other parameters as well?

Easiest way to do it would be either change the front cover and run S5 everything(not hard at all) ,or have the S5 ECU modded to delete the limpmode so everything will run fine regardless of trouble codes the ECU might be receiving.Youll just have to stare at a check engine light all the time,if you decide to hook it up.

Heres all the info about the OMP thats in the factory service manual,on page D16-D-18....
http://www.teamfc3s.org/main/factory...ion_system.pdf

And here the OMP wiring in relation to the ECU and S5 engine harness,on page F1-8
http://www.teamfc3s.org/main/factory..._non_turbo.pdf

NZConvertible

Building a controller that can operate the OMP exactly as the S5 ECU does would be far more difficult than swapping on the front cover and TB from an S4. Even if you could build the controller, it's probably safe to say you wouldn't know how to programme it to give the correct lubrication at all engine speeds and loads. The only people I know who've done that are Haltech and MoTec...

But for entertainment purposes, here's the releveant sections of the ECU wiring diagram. There's not much to see; all the clever bits are inside the ECU.

Stepper motor: http://i8.photobucket.com/albums/a47...urboECUOne.jpg

Position sensor: http://i8.photobucket.com/albums/a47...urboECUTwo.jpg

rotoman2

you guys are awsome. thanks a lot. I'll save my front cover and mechanical OMP link for the next rebuild.