Gavs Eunos Roadster

~Slideways~ · May 20, 2024

Here's a video of the first start, I'm genuinely surprised how well it idles from cold etc.

Cold start is bad but then it idles straight away.

This is with the fuel pump jumped via the diagnostics plug. Hopefully I'll figure out getting the ecu to trigger the fuel pump.

https://youtu.be/toCfkd0BbO8?si=jZJvmsDtOWLo17_n

Themi · May 20, 2024

I think my friend had similar if not identical issues to what you're facing re the TPS and fuel pump. If you want to PM me about it I can put you two in touch.

The adapter boards went through a few revisions and did need some work to get every feature going as expected. While you're in there you should do the ULN proto board stuff for the tacho, saves from having to "do it tomorrow" for years... Not that I'd know about that?

https://speedyefi.com/ulns-and-pullups-and-launch-oh-my/

~Slideways~ · May 20, 2024

1 hour ago, Themi said:

I think my friend had similar if not identical issues to what you're facing re the TPS and fuel pump. If you want to PM me about it I can put you two in touch.

The adapter boards went through a few revisions and did need some work to get every feature going as expected. While you're in there you should do the ULN proto board stuff for the tacho, saves from having to "do it tomorrow" for years... Not that I'd know about that?

https://speedyefi.com/ulns-and-pullups-and-launch-oh-my/

Cheers for the link, I'll do some research on using the ULN2003. Have PM'd.

tigerstyle · May 26, 2024

On 21/05/2024 at 08:58, ~Slideways~ said:

Cheers for the link, I'll do some research on using the ULN2003. Have PM'd.

You definitely want the ULN makes things easier for the fuel pump, and I guess you're pretty happy re-wiring stuff to make it 'work' I'm no expert but used the same stuff in the same car and was happy with the results.

The resources I used the most were:

https://www.miata.net/garage/ECU Pin-Out 90-93 MT.pdf
https://www.pcbway.com/project/shareproject/Mazda_Miata_48_pin_rev_C_Speeduino_connector_adaptor_ecu_ems.html (This isn't the link I used before, the board deign used to be on Github with the PCB schematic, I opened it in the easy to use Fritzing PCB software to check each pinout directly. I'd just print them on some A3 paper and multimeter out each connection and make a copy that way if I couldn't find the files online now) There are lots of versions of the adaptor board with small differences, it's probably quicker to multimeter out what you have and do that rather than trust it has been built to some random spec anyway tbh.
A long time staring at the IDC 40 Pin table here https://wiki.speeduino.com/en/boards/V04

I then added jumpers from the IDC 40pin on the breakout board to unused pins in the Mx5 ECU connectors and added connections for Sequential Injection + Sequential Ignition (so 2 extra for each) 1 for the fuel pump (coming from the ULN, into the MX5 ECU connector then ran a new wire from the ECU out to the fuel pump relay using an unused precrimped ECU pin from elsewhere) Some TPS stuff as you said, one for the Wideband, maybe some others, rev counter? Long story short the back of the plug and play adaptor only looked slightly modified after that :grin:

I then used the Miata ECU PDF to strip away all the unused wires from the loom because lightweight racecar of course.

I guess it goes without saying, but I approached it with the mentality of making it do what I wanted it to do, not trying to make it work how Mazda intended, so adding moving deleting wires? No worries, just documented to myself what I did

~Slideways~ · June 1, 2024

On 26/05/2024 at 13:03, tigerstyle said:

You definitely want the ULN makes things easier for the fuel pump, and I guess you're pretty happy re-wiring stuff to make it 'work' I'm no expert but used the same stuff in the same car and was happy with the results.

The resources I used the most were:

https://www.miata.net/garage/ECU Pin-Out 90-93 MT.pdf

https://www.pcbway.com/project/shareproject/Mazda_Miata_48_pin_rev_C_Speeduino_connector_adaptor_ecu_ems.html (This isn't the link I used before, the board deign used to be on Github with the PCB schematic, I opened it in the easy to use Fritzing PCB software to check each pinout directly. I'd just print them on some A3 paper and multimeter out each connection and make a copy that way if I couldn't find the files online now) There are lots of versions of the adaptor board with small differences, it's probably quicker to multimeter out what you have and do that rather than trust it has been built to some random spec anyway tbh.

A long time staring at the IDC 40 Pin table here https://wiki.speeduino.com/en/boards/V04

I then added jumpers from the IDC 40pin on the breakout board to unused pins in the Mx5 ECU connectors and added connections for Sequential Injection + Sequential Ignition (so 2 extra for each) 1 for the fuel pump (coming from the ULN, into the MX5 ECU connector then ran a new wire from the ECU out to the fuel pump relay using an unused precrimped ECU pin from elsewhere) Some TPS stuff as you said, one for the Wideband, maybe some others, rev counter? Long story short the back of the plug and play adaptor only looked slightly modified after that

I then used the Miata ECU PDF to strip away all the unused wires from the loom because lightweight racecar of course.

I guess it goes without saying, but I approached it with the mentality of making it do what I wanted it to do, not trying to make it work how Mazda intended, so adding moving deleting wires? No worries, just documented to myself what I did

Hey thanks heaps for the info, super helpful. I got the Fuel pump and fan working with a ULN2003a chip, before I got it working I thought the ULN was faulty on pin 45 because at the time I couldn't get it to prime.

I was checking things with a multimeter and saw that the Arduino was sending 5v to pin 45, but still no pump. Checking some more and I managed to slip and short the 12v and Ground then the magic smoke came out of the adaptor board.

Now the radiator fan comes on permanently.

Yay fun... removed the speedino board and adapter then found that it looks like it had nuked the trace (on the adapter break out board) from 12v to the pin on the ECU connector (pin 1A from memory).

Fck...

So I soldered a wire to bridge the connection with the dead trace, doesn't look like it connects to anything else.

Now it's back to the rad fan being controlled properly, i.e. I can change Tunerstudio to trigger it at say 10deg C so it comes on on demand.

But now I don't see any RPM and no LED's to show ign or injector activity. Fck sake.

Had a close look at the Speeduino board and adapter. All looks fine, checked for burnt components, all look ok. Checked for continuity of resistors etc.

Checked for continuity for the Crank and Cam signal wires.

Put Tunerstudio into the hardware test setting, I can now trigger injectors and ign with the board LED's firing and the I can hear them in the engine bay. So that's good.... but what is wrong?

I assume I am still not getting crank or cam signal.

Possibly next I'll try bypass the breakout board and IDC cable for the crank and cam signal.

Or maybe bypass the whole board and wire directly to the ECU plug.

Cars are fun.

EDIT: so I have MAP, TPS, intake temp, water temp, working fuel pump and rad fan. But no RPM, no injector pulse. Maybe a mosfet is fried or still a trace issue.

~Slideways~ · June 1, 2024

I even tested it in my Yellow MX5 and same behaviour so it's definitely nuked something on the ecu or break out board.

Annoying but I guess it's not like I nuked a $2k ECU and it seems to be mostly functioning.

~Slideways~ · January 20

So this thing, I some how messed up the clear coat and after about 6 months it started cracking like crazy. So I parked it with the plan to sand back, since then I've painted half of another mx5 and that has not cracked so I'm confident I can get it right.

Have mostly sanded back again, not the most fun job so I decided I should get back to the ITB thing.

Last time I had it running with the first test of the 3d printed adapter and running on the speeduino. As above I accidently shorted and messed up the speeduino. At the time I built another one of the later 04.3d which is a nicer layout but uses smaller resistors and some other differences so I couldn't use the part as planned to try figure out what was wrong with the 0.4.3c

Since then I think I might have figured out what is possibly failed on the original one but need to buy some components.

For the adapter I wanted to redo it with a few improvements:

- remove the cutouts in the flange.

- thicken the flange from 10mm to 12mm.

- change the intake ports to be oval instead of having the injector cutouts (since they won't be there), so it's a smoother air flow path.

So here I am reminding myself how to use Fusion: