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Help with building your Speeduino, installing it, getting it to run etc.
By Adam Martin
Hi all! ~excited to join the community.
Bit of backstory...
Some Japanese bloke decided that the passenger footwell was the ideal place to locate the factory ECU, 20 years of 'British summers' later and it no longer enjoys swimming... or for that matter, working.
For the same cost as buying a second hand ECU, ignition barrel, immobiliser controller, and locks for the doors, boot, centre console, and glovebox, I thought I would give a Speeduino a go. It also gave me an afternoon of soldering to break the boredom of lockdown. I have a 0.4.3c board with the dual VR conditioner fitted.

I'm struggling to find much info on running a Speeduino in a mk2 mx5, I highly doubt I am the first to try it!

Is there much difference between the NA8 and the NB8A?

Does anyone have a base map?

Any pin to pin wiring instructions would also be greatly appreciated!
I have got the Mazda wiring diagrams, and have sussed that I have 2ch of spark, 4ch injectors. I also have heated O2 sensors, not sure about how the heater circuit is run though...

What do I do with the EGR solenoid? Is it a case of EGR delete or is it something TunerStudio can handle?
By pani
Hi mate

I'll try to answer what i know.
Lots of nb's out there with a speedy.

As far as i know only the connector pinout changes. There is a basemap that you can use that you can download from Speedyloader. If you have the wiring diagrams then you should be good to go. Google is your friend, search for megasquirt nb pinout. All the base sensors and pinouts are the same pinwise. Heated O2 sensor gets it's own power the signal is fed to speedy. Altough I would recommend going for a WB as it should make things easier to tune. Speeduino cannot handle EGR. There are kits out there that delete the EGR circuit. Search in the forum there is a lot of info on the NB.

https://www.google.com/search?q=miata+n ... AXoECBAQAw

https://www.miataturbo.net/megasquirt-1 ... eet-14934/
By Adam Martin
Thanks pani,

I just keep finding info for the 01-04 model, I take it I just ignore the vvt aspect of those?

WBO2 is where I intend to go on the next paycheque, but the question I had really was the fact that the heater in the stock O2 is returned to the stock ECU on pin 1U, obviously speeduino isn’t built to handle this. I’m already putting an arduino uno in to drive an rfid sensor and relay to break the starter circuit as an immobiliser, is it a circuit that should be switched by that instead?

The EGR, can it be ignored or would it need a delete?

Thanks for your help, I just don’t want to hurt her.
By Sneip
Hi Adam,

I have an MX5 NB 1.6l from 98 should be the same spezification as yours. I also use the v0.4c board and I got the car running quit good. I use a Add On PCB that I designd to reuse the OEM ECU Connector with the Speeduino so I don´t have to cut in to the wires.

I attached some pictures from my Pinout and the PCB itselve hopfully that helps a little to get startet.
K1 is the Connector from the Speeduino PCB and K2 ist the OEM Connector from the car. K3 is an aditional connector I added in the Proto area so that I can locate the ULN 2803 for Fan, Tacho and Fuelpump on my Add on PCB.

I also build the alternator control circuit on the Add on PCB to make a Plug and Play solution for the NB.
IMG_4222.jpg (2.74 MiB) Viewed 444 times
C77C57A2-8C32-4FD6-9867-2AD1FE5A66CC.JPG (1.24 MiB) Viewed 444 times
IMG_4223.jpg (2.19 MiB) Viewed 444 times
Pinout.jpg (250.72 KiB) Viewed 444 times
By Adam Martin
Its assumed that there are some rotten pins on my factory harness, so its likely I will have to cut in anyway :?

I was also under the assumption that I could connect fuel pump relay to K1-14, the Tacho to K1-16, and the fan relay to K1-15?
is that not the case? What is the purpose of the ULN2803? Sorry, I do electrics, not really electronics, bit of a n00b. :oops:

attached is the plan of the immobiliser I was talking about.
(458.28 KiB) Downloaded 24 times
By Sneip
The ULN2803 is an Darlington Transistor Arrays. It provides you with some additional high current outputs to power your cooling fan, fuelpump an so on.

The pins on the Speeduino alone have not enough power for that.
By theonewithin
You may not need the ULN.

By default the Speeduino has multiple outputs.

You can repurpose any of them for FP.

Such as Boost, VVT etc. Just need to change their pin assignments within Tunerstudio.

Make sure you set the original output to something other than board default first though
Sorry this isn't in the wiki yet. Still working on it.

Lots of info to put in.
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