OMP: Prototype tester

[SprintRX8]

So, a plea, is there anyone who is willing to donate the two plugs that connect to the OMP (6 pin stepper motor connector and smaller switch connector

Drop me your address.
I have a spare engine loom.
With these connectors.

[casey]

Thanks SprintRX8 - you have a PM.

OMP plugs now sorted

[SprintRX8]

Received.

At the Barn tomorrow so will grab the plug's off the spare loom and posted to you.

[thatturborx8]

I am quite certain that the unit you have there is not built in the UK but in Australia.
The purpose of the unit was to control the oil metering pump when 20 years ago owners wanted to change to an aftermarket ecu that could control boost via map but no standalone ecus were capable of controlling the OMP.
Due to lack of solutions most of the owners used to blank the omp and go for premix but running a lot of premix was diluting fuel,clogging injectors,fuel pumps and other components which was bad for high horse power applications so somebody came up with this controller.
It has also been proven that injected oil cools the seals and helps them wear less than by using only premix so people wanted that pump working.
Only a few units were made and sold because Haltech and Adaptronic listened to the enthusiasts and quickly introduced an EOMP controller input in their ecu's.
I do not think that the unit was performing same checks as the factory ecu,nor as your device does so i do think that it will not help you in your research.
The unit would only trigger an issue if there was a short,open circuit or voltage abnormality on the stepper motor and position switch.
To add on to that i have opened a few pumps and most of them have failed due to corroded or faulty stepper motor.
Most of these cars have or have had a coolant leak from the thermostat housing straight onto the omp.Most of the pumps are now over 15 years old so they have probably outlasted the engine and shell.
For now we can still find new ones but it will be a right mess when Mazda will stop producing them.
Last but not least, it is more than obvious to me that if a "reverse engineering" company like ECUtesting opens up a brand new OMP and a few failed ones they can establish the most common failure cause and develop a "fix" as long as they can source or manufacture replacement parts however the RX8 omp market is too small for somebody to bother unfortunately.

[casey]

That is very interesting info about the controller. I'll do some looking on the Aussie forums to see if I can find out anything further.

To add on to that i have opened a few pumps and most of them have failed due to corroded or faulty stepper motor.

I'm aware that this can be a failure mechanism, but I have experience of several units where everything functions as per the published Mazda spec. I have dismantled one completely to find no internal corrosion and the stepper motor works as it should. If I can determine what electrical parameter(s) the ECU is using to trigger a fault code and instigate limp mode, then it is possible to consider repairing units, or at least cannabalising a number of units to construct a good one. The quest continues, but your extra info on the controller is intriguing, and very helpful.

Here is a snapshot of part of the circuit board in the controller with the company info. The soldering and general construction of the unit (especially if if was designed to be used as an OMP controller in a car) leaves a lot to be desired!

It's curious the PCB text mentions, "now supports RX8's" as I've never come across any info on the this unit whilst researching OMP's on UK and US sites. If it was marketed only in Oz, that could explain why I've never come across it before.

[warpc0il]

Zero hits here http://www.ausrotary.com/search.php?key ... chnologies

However...

eomp.info by Jason Dixon no longer exists but it was captured by the archive machine
https://web.archive.org/web/20130331005 ... eomp.info/
and we have a winner!

The Eomp project is the work of two rotary engine engineers from Perth, W.A., who set out to design a standalone electronic controller that drives the factory electronic oil metering pump found on the Mazda 13B rotary engine supplied in RX7 series 4's and upward and RX8's.

The EOMP controller consists of a backlit LCD handset and detachable wiring loom. Wiring looms can be ordered with factory Mazda plugs to enable a plug'n'play install for those who are wanting to keep the factory look, and standard wiring looms with bare ended wires for the custom install.

We also carry a 3 Bar map sensor for anyone wishing to grab one of those along with ordering the EOMP controller. Check out the videos and leave a comment or drop us a line at admin@eomp.info.

[casey]

Getting somewhere...a slightly different casing, but looks like the same function, but slightly later version:



So, this controller may be of limited value in discovering why the ECU is "condemning" OMP's.

What is more intriguing though, is how can this unit be installed on an RX-8 and "fool" the ECU to think the OMP is connected and functioning? OR, is this controller intended to be used when the OEM ECU is replaced with an aftermarket ECU? I think that must be the case, as early 3rd party ECU's were (as I understand it) not capable of providing OMP control as it tied up too many outputs to drive the stepper coils. Modern 3rd party ECU's are capable of controlling the OMP, so this controller is now redundant.

[casey]

I read your first post Dave ("zero hits"), then I found the Jason Dixon EOMP material and posted it above, then saw you'd found essentially the same stuff and edited your post ("However...") to include it

Right, must get some sleep - goodnight

[thatturborx8]

What is more intriguing though, is how can this unit be installed on an RX-8 and "fool" the ECU to think the OMP is connected and functioning?

As mentioned in previous post,the controller is pointless if you have the stock ecu.
If one goes to an aftermarket ecu that is not capable of controlling the omp then they use this controller.
It says "now supports RX8" because the controller was designed before Mazda has released the RX8 but once it has been released the owner has made another version which supported the RX8 omp too.

[warpc0il]

Not entire pointless,as it gives another means to bench exercise the OMP.

However, it doesn't get us much further in identifying what can cause a functioning OMP to fail the pre-flight PCM checks, when it's within the published tolerances.

I wonder if Jason is contactable and if he has an experience or thoughts on that issue.

[qwakers]

every single failure i've seen so far has been the sensor sticking. it sticks at the full flow position. if you remove the sensor from the pump, insert a screwdriver into the slot and gently rotate it anticlockwise, it springs back to its home position. it will then work fine. ive revived 3 like this recently.

[casey]

That is a very interesting input James. An intermittent fault like that could explain why I can't easily reproduce it with my tester.

I'll see if I can reconfigure my prototype (or construct another one) to continously exercise the sensor and see if I can reproduce this "sticking" fault.

[Delanor]

every single failure i've seen so far has been the sensor sticking. it sticks at the full flow position. if you remove the sensor from the pump, insert a screwdriver into the slot and gently rotate it anticlockwise, it springs back to its home position. it will then work fine. ive revived 3 like this recently.

Any indication what causes it to stick?

*
*
Del.

[qwakers]

no. i would assume wear creates a burr at the end of the travel that it catches on...

[warpc0il]

I wonder if the stop wears, so it can travel beyond the original design limit, and then get caught.

[qwakers]

possibly.

[casey]

I wish I could acquire a spare OMP position sensor to disassemble and see the mechanism. I am reluctant to destroy any of the 3 I have, as they all seem to function OK.

There are videos showing the dismantling of TPS (Throttle Position Sensors) units, many of which look externally identical to the OMP sensor, but they have a "conventional" potentiometer inside, sweeping from zero ohms to whatever the max resistance might be. The position sensor on the OMP is open circuit (OFF) for most of its travel, then changes to 400 ohms (ON), or less, abruptly. This suggests it might be "partial" potentiometer track on which sliding contacts pick up the resistance track only near the end of travel. This would be easy for the manufacturer of TPS units to make, simply by inserting a different track to a "full sweep" TPS style resistance track.

Although this video is not of a TPS with externally identical contruction, it does show how easy it would be to insert a different resistance track inside - the track just clips out!

[warpc0il]

I try to encourage people with "failed" OMPs to contact you.

Sent from my SM-G556B using Tapatalk

[qwakers]

i used to have a broken but working in theory omp sensor (connector broken off) i think it ended up on a omp that was on a engine i sold as bare to chrisholmes. i suspect he binned it but on the off chance it still exists?...

[casey]

Thanks James. It's a long shot, but I've just messaged Chris to see if he still has that OMP.

[casey]

Thanks also to SprintRX8 and Paul_13 for each kindly sending me a set of OMP connectors.