www.RX7fb.com

ian65 wrote: ↑Wed Jun 30, 2021 10:01 pm

Casey wrote: ↑Tue Jun 29, 2021 4:26 pm That's the emissions control gubbins

So if a car had a rats nest delete and the nikki taken off then this cpu is obsolete?

That is my understanding, but there may be circuits routed through it which might need attention. I haven't looked at the detailed circuit diagrams associated with that module to be sure.

Casey wrote: ↑Wed Jun 30, 2021 11:25 pm

ian65 wrote: ↑Wed Jun 30, 2021 10:01 pm

Casey wrote: ↑Tue Jun 29, 2021 4:26 pm That's the emissions control gubbins

So if a car had a rats nest delete and the nikki taken off then this cpu is obsolete?

That is my understanding, but there may be circuits routed through it which might need attention. I haven't looked at the detailed circuit diagrams associated with that module to be sure.

I recall Tim White suggesting that it may form part of the Auto Choke circuit, specifically the fuse which lives on the outer casing.

"Mark 1" tester now completed





If anyone has any of these units knocking around and would like to know if they work, I'm happy to test for FREE, you just need to cover shipping costs. If I can identify a fault, I'm happy to diagnose and quote for parts to repair (labour free). I'm not in this to make money, just helping out the community as others have helped me.

Mate this is fantastic Kudos to you for figuring this out and devising this testing rig, what a great thing. I bet there's not another guy anywhere who's sussed this out and made a test bed for one...... in the days of plenty of spares, new dealer parts and plentiful 2nd hand parts these were just plug and play and throw the old one out if it didn't work.... those days have gone so to able to test and repair is amazing.
I'll see if I can dig my spare one out for you to test for me if you don't mind?

Really impressed, well done!

Thanks Ian - no problem to test your "CPU" if you can locate it

Better to test and, if necessary, repair these modules to keep originality if possible.

The module Dave donated for the tester development is now fully functional after the 2 dead transistors were identified and replaced. Failure was probably caused by the ignition key illumination lamp blowing and going short circuit and overloading those components, as there is no overload protection.

I needed a (relatively) simple challenge to warm up my rusty electronics skills before I moved on to another, more adventurous, rotary related project. A tester for RX-8 OMP's, which are beginning to "fail" quite regularly. When I say fail, the ECU runs a test on ignition start and, if the incorrect conditions come back, the ECU throws a CEL and the car goes into limp mode. It happened to me, so I'm keen to find out why! I have a theory on why they fail the ECU test and, if correct, they should be repairable. That's good news, as they are hard to find from breakers due to demand, cost about £80, if they can be found, or cost around £400 new from Mazda

This requires some software and hardware to control the stepper motor, plus monitor a sensor switch on the OMP.

Some progress though, I've removed the stepper motor from the OMP and connected it up up to an Arduino controller with some "off the shelf" software that I have tweaked (the stepper motor is bottom right in the pic). I have managed to get the motor to step through a complete revolution, then reverse a complete revolution. Early days!

Excellent work Malcom, a great service for first gen owners! Very cool to be putting that knowledge to good use helping RX7 and RX8 owners!

I am going to try and 3D print a cover that goes over the flasher relay as it's missing on mine, then I will send it to you for diagnosis and repair

That CPU tester is a seriously awesome bit of kit. I suggest that it would not look out of place in an episode of Thunderbirds.

I might have to remove my replacement CPU and send it for testing.

Really impressive work Malcolm, well done mate.

Bloody awesome work there aye bro!

Casey wrote: ↑Sun Aug 08, 2021 7:41 pm "Mark 1" tester now completed

MCC_7147.JPG






If anyone has any of these units knocking around and would like to know if they work, I'm happy to test for FREE, you just need to cover shipping costs. If I can identify a fault, I'm happy to diagnose and quote for parts to repair (labour free). I'm not in this to make money, just helping out the community as others have helped me.

I think this is amazing!!! Well done on figuring this out, well out of my brain function capacity. Love it.