Any questions you have before you begin buying, building and installing.
User avatar
By iltheo84
#49900
First post here, I'm researching some information about the modifications that need to be done to the wiring in order for a MX5 PNP Speeduino to work with a late 1.6L Euro car.

In my understanding so far, these later models switched to full sequential injection and used a 2-plug harness similar to the '94-'95 1.8L model, with some differences mainly for the fuel pump management and said sequential injection.

The only table I was able to find online is this:

Image

So if I buy a PNP (I'm planning to purchase the CORE4 kit with IAT, TPS and onboard WB, eliminating the stock MAF) I must adapt the wiring from the yellow column (1.6L early 115hp model) to the first column.

In the Speeduino Wiki, there is a paragraph about settings for the 1.8L engine (fuel pump output on pin A9, tacho out on pin 49, demister wire if needed): would it make sense to use those in my configuration, since my car mostly uses the same wiring?

If I set Speeduino to use sequential injection, would the hardware already be configured to use the ECU outputs 2Y and 2Z for injectors 3 and 4?

Thanks for any help/suggestion!
By pani
#49902
Been there done that. I was one of the beta testers for the DIY-EFI Core 4 PNP MX-5 solution. James provided me the exact same hardware you are buying. You need do nothing on the wiring harness.
Just keep in mind.

1. REMOVE THE ST SIG FUSE
2. Jump the solder pads for the crank sensor on the bottom side of the pcb inbetween the 48 pin plug connector
3. Jump the connection to use the onboard WB
4. Set board to Core 4 and injection to sequential, MAP sampling to Instantaneous.
5. Fuel pump output to pin A9

It's an excellent piece of kit that bolts straight to the stock ECU case. I used also sequential ignition with VAG cop's. It has onboard additional drivers if you want to go seq ignition. Also outputs for boost, launch. Inputs for flex, knock etc.
More when you get the board. Give me a shout I'll send a tune. Although James will probably provide the same one.
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User avatar
By iltheo84
#49905
pani wrote: Wed Apr 28, 2021 9:11 am Been there done that. I was one of the beta testers for the DIY-EFI Core 4 PNP MX-5 solution. James provided me the exact same hardware you are buying. You need do nothing on the wiring harness.
Just keep in mind.

1. REMOVE THE ST SIG FUSE
2. Jump the solder pads for the crank sensor on the bottom side of the pcb inbetween the 48 pin plug connector
3. Jump the connection to use the onboard WB
4. Set board to Core 4 and injection to sequential, MAP sampling to Instantaneous.
5. Fuel pump output to pin A9

It's an excellent piece of kit that bolts straight to the stock ECU case. I used also sequential ignition with VAG cop's. It has onboard additional drivers if you want to go seq ignition. Also outputs for boost, launch. Inputs for flex, knock etc.
More when you get the board. Give me a shout I'll send a tune. Although James will probably provide the same one.
Thanks pani!
That's some excellent info and great news, I don't mind tinkering with wiring and soldering but I'm glad no major modifications are needed! :D
I see two 1Kohm resistors added on your board as pull-ups for the RPM signals, are those needed too or are they integrated in the design in the final product?

I plan to buy the kit in the next weeks, then I will start working on it and I will surely get back to you!
Thanks again! :oops:
By pani
#49911
iltheo84 wrote: Wed Apr 28, 2021 9:31 am
I see two 1Kohm resistors added on your board as pull-ups for the RPM signals, are those needed too or are they integrated in the design in the final product?

I plan to buy the kit in the next weeks, then I will start working on it and I will surely get back to you!
Thanks again! :oops:
That was a pre production beta board that was in the - well - beta stage! The final boards need nothing.
User avatar
By iltheo84
#50131
Bdrules20 wrote: Wed May 05, 2021 4:42 pm If I ever needed a reason to get involved with speeduino, this thread is all it would take to convince me that I found what I’ve been looking for.
Indeed!
In fact, after pani's reply, I bit the bullet and ordered the kit, it should be delivered today 8-)

I also picked up an extra MPX4250 sensor and I would like to use it as a BARO sensor, but I still have to figure out how (or bettere, WHERE) to wire it to the CORE4 board.
I understand the sensor needs GND and +5V supply, but since the PnP daughterboard already has an internal MAP sensor, I assume the MAP pin of the CORE4 board is connected to that unit.
Should the external BARO sensor be wired to one of the SPARE pins? Which Arduino pin do they correspond to? :?
By Jama
#50133
iltheo84 wrote: Fri May 07, 2021 9:06 am
Bdrules20 wrote: Wed May 05, 2021 4:42 pm If I ever needed a reason to get involved with speeduino, this thread is all it would take to convince me that I found what I’ve been looking for.
Indeed!
In fact, after pani's reply, I bit the bullet and ordered the kit, it should be delivered today 8-)

I also picked up an extra MPX4250 sensor and I would like to use it as a BARO sensor, but I still have to figure out how (or bettere, WHERE) to wire it to the CORE4 board.
I understand the sensor needs GND and +5V supply, but since the PnP daughterboard already has an internal MAP sensor, I assume the MAP pin of the CORE4 board is connected to that unit.
Should the external BARO sensor be wired to one of the SPARE pins? Which Arduino pin do they correspond to? :?
There is space on the CORE4 module itself for an SMD Baro sensor.
But given you have a through hole sensor, wire the signal pin of that to SPARE2 and then use pin A14 within tunerstudio.

There are many 5v and gnd pins you can use, you can see these all on the back of the daughterboard.

James
User avatar
By iltheo84
#50136
Jama wrote: Fri May 07, 2021 11:34 am There is space on the CORE4 module itself for an SMD Baro sensor.
But given you have a through hole sensor, wire the signal pin of that to SPARE2 and then use pin A14 within tunerstudio.

There are many 5v and gnd pins you can use, you can see these all on the back of the daughterboard.

James
Thank you James!
I picked up a trough hole sensor because I have a cowl intake in my MX-5 and I will try reading the pressure signal from the cowl, since at speed it can be at a different pressure than ambient.

Thanks for the info on the Spare2 pin! 8-)
User avatar
By iltheo84
#50179
pani wrote: Sun May 09, 2021 4:47 am Correction on the fuel pump pin. It is 36 not A9. I just checked my tune.
Ok thank you, so on the 90hp 1.6L the pump pin is Default.

Would it make any sense to unsolder the MAP sensor from the board, mount it inside the engine bay so that the vacuum hose is as short as possible, and wire it back to its original position with some sort of shielded cable, such as a USB cable?

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