NC ABS ECU not working

[tbro]

you need to pm andy-w and ask him, he's the guru with adaptronics.

[Driver06]

Does anybody know what the answer is here?

I have swapped an LFX into an NC and want to get the ABS working.

[greenMachine]

Watching this with interest.

My understanding is that all the control electronics for the ABS are in the ECU for the NC, not the ABS unit itself (like the ADM NB8B). Some NA and early NB ABS units have a separate computer which perhaps could be adapted, but all these are only three channel.

One of these could be adapted to drive the NC unit if you could live with only three channels, providing there are no residual control electronics in the NC ABS unit. In that case you would need to match the ABS computer with the associated ABS unit. These can be found in the 10AE, and imported half cuts from Japan though how many of the latter are still around might be another matter.

The simplest and probably cheapest solution (unless Andy-w has an off-the-shelf solution) would be to swap in an NB8B ABS unit and live with only three channels. I know Deckspeed have done a number of retrofits of this system into non-ABS cars (NA/NB), I don't know about NCs though.

[Driver06]

Thanks greenMachine,
I currently have both the GM ECM (running engine and transmission standalone) and the MX-5 ECM (with nothing plugged into the engine loom port).
I figure that the ABS is missing inputs from the bits that the GM ECM is running.

[greenMachine]

The issue is that you want the NC ABS to work? For this you will need to know what the inputs are - power, wheel speed (ABS sensors), handbrake probably, an output to a warning light, maybe more. There may also be internal programming that requires 'live' engine data (say engine speed related to wheel speed, maybe windscreen wipers, who knows ...) I just don't know, because the ABS uses the engine computer, all that engine and body data is available to the ABS if the Mazda programmers wanted to use it. If you want to just cut the wires to the ABS from the ECU, provided you have a wiring diagram and some understanding of what signal characteristics the ABS needs to see (not just where the signal comes from), that may be doable, but I would not like to be the one pioneering it!

The stand-alone ABS is much simpler, you know what is going into it, feed it that and watch it work.

Back in the day, parallel engine management was a thing. Aftermarket ECUs were pretty crude and lacked the ability to do everything that the factory ECU could do, so the aftermarket computers were wired in parallel to the factory ECU. The factory ECU thought it was running the engine, so everything worked as the factory ECU thought it should, but the aftermarket ECU was actually doing the ignition and fuel so the performance was happening, just out of sight to the factory ECU.

This may offer some possibilities, but with the NC computer being so highly capable (especially in heuristic mode) it may be too smart to operate when it 'knows' things it is supposed to be managing are not responding. The new engine being a six rather than a four, and having the associated fuel and air differences, only adds another layer of complication and difficulty if you wanted to go down that path.

I can only reiterate, if you want ABS a stand-alone system seems the way to go. It doesn't have to be Mazda, as long as you can get a wiring diagram for it you can make it work.

The only other road you can explore is the ECU programming. There is a DIY tablet based system from the USA that offers access to the NC ECU. This is intended for engine management purposes, but it may also offer some insights into the ABS operation, and the extent to which it can be made to work without engine data. Try the big board (Miatanet), that should allow you to contact the relevant people.

You also probably know that there are at least a couple of LFX projects on MTnet, you could trawl that site for any insights into whether/how they handled ABS.

[Driver06]

Thanks again for the comprehensive response,
Yes it is finding what CAN packets drive the ABS and how the ABS uses same, where I have hit a brick wall.
I currently have an Arduino reading GM packets from the GM ECM and transmitting the required MX5 packets on the MX5 CAN bus to operate the OEM dash. If I could find out what packets the OEM ABS needs then I think I can possibly just do more of the same on the same Arduino.
I have put a Brembo 4 pot Big Brake kit on the fronts and with AR-1s on I haven't had any lockups even under some very severe braking but I do want to get the ABS working even if I end up turning it off.
I read a MOTOR mag article last night that said that Flyin'Miata have an LS3 swapped ND with ABS. I have just sent them an Email asking them how they did it. Fingers crossed.

[Driver06]

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[Driver06]

Wow, great response from Flyin'Miata in the US.
They indeed do have the ABS working on all their ND swaps.
To date they are all LS swaps. They contracted a guy to program the GM ECM to generate Mazda CAN frames to maintain the full functionality of the ND. This was a mammoth reverse engineering job.
They are forwarding my email to him and he will be in touch.
Lets hope that the NC and ND aren't too different.

V8Roadster have done a number of LFX swaps but have removed the ABS on all of them.

Still fingers crossed.

[Driver06]

They tell me that the ND/Skyactive is vastly different to the NC/MRZ.
After the time and cost of doing an ND ECU an NC one is most unlikely.
It looks like I'm going to have to try to figure this out myself.
Without knowing the CAN frames that the ABS Control Module uses make this task practically impossible.
I already have an Arduino reading frames from the GM CANbus and transmitting relevant frames to the MX-5 CANbus to operste the OEM dash.
So if I knew what the ABS needs then I'm sure the goal is achievable.
If anyone who has this knowledge or knows someone that does or might, I will appreciate any help I can get.

[Okibi]

Brace yourself when you research the price
http://www.bosch-motorsport.com/media/c ... e_epdf.pdf

Seems like it might be cheaper to adapt a standalone factory system.

[Driver06]

My brother's mate is a Bosch agent and for some reason it is cheaper here in Australia than in Germany but still over $8000.
The kit includes everything including the programming software.
If all else failed with the MX-5 ABS I was seriously going to consider this.
The killer here though is that it is specifically not approved for road use.
I really want (and need ABS) as I want to run good tyres and can't afford the flat spotting.
Continuing on.

[Guran]

Much cheaper to learn to drive it without ABS. Plenty of NA and NB8A track cars being dríven very quickly without ABS. Just saying.

[Driver06]

No, it doesn't take too many $400 flat spotted tyres to add up to a lot of money and they way I am going something bad is going to happen.
Also the car is very fast, at my braking point I am often over 30kph faster than in my NA.
The way that I am managing this ATM is to brake way early, hence the lousy times.
I am also thinking that the Brembo big brake kits might be a mistake.
They take so little pressure for heavy braking that I get no feedback through the pedal.
When I lock up, ease off, get traction back, I most often immediately lock it up again, meanwhile the tack is running out fast.
If I can't get the ABS sorted soon I will put the OEM brakes back on with some upgraded pads and see.

[greenMachine]

I am also thinking that the Brembo big brake kits might be a mistake.
They take so little pressure for heavy braking that I get no feedback through the pedal.
When I lock up, ease off, get traction back, I most often immediately lock it up again, meanwhile the tack is running out fast.
If I can't get the ABS sorted soon I will put the OEM brakes back on with some upgraded pads and see.

You definitely have a brake problem that ABS is not going to fix (but it may hide it). It sounds like a mismatch between the sizing of the wheel cylinders and the master cylinder - did you do any research on the ratios of these cylinders before you installed the Brembos?

First thing would be to disconnect any booster assistance to reduce the pedal sensitivity. Then change the pads to ones that have less initial bite. By then you should have done the homework on the wheel cylinder volumes so if that doesn't bring the grabbiness under control, look at changing the master cylinder for one that is better matched to the wheel cylinders, or changing the callipers to match the wheel cylinders.

You also need to look at the rear brakes in the same way at the same time, matching wheel cylinders to the master, or changing pads to get a proper F:R braking balance. From the sound of your description, the rears are probably just along for the ride.

Forget ABS for now, get the fundamentals right, then see how badly you want ABS.

Just my 2c.

[4sfed5]

You need an rx8 non stability control abs module. These will work happily in stand alone and are a direct fit for the Mx5 one. Part #F1y1-43-7AO