MS1 V3 Full Standalone on 1990 B6ze

[ogwazza]

So I finally got sick of the Miata loom and all the crap that comes with it eg: pgr solenoid valve this and diagnostic box thing that etc. Who actually knows what they do!!

So below is the loom freshly out of the 323

and now you can see my standalone m.s loom... a little bit more tidy and 1/10th the amount of wires.
Im using Joe Perez's idea of scabbing a RX7 afm IAT.


I am just needing to solder the loom into the db37 and add the couple of relays. As it is in a foreign body I also have to add alternator and starter to the loom as well as the 80amp and 30 amp main fuses. However this will be seperate.

However I have a couple of questions for the wealth of knowledge that lies in the m.net:
1. Do I need to add a relay for the fan output, or will the MS send enough power to the fan?
2.As I have modded a 2nd hnd MS- how do I know where Iac1a and 1b translate onto the db37?
3.I cannot get a 1n1002 diode in NZ at the moment to bridge across my EBC solenoid, so I bought a 1n1001 and a 1n1003- will either one of these work?
4.My MS diagram is limited, but it shows the O2 sensor as a 2 wire, mines only 1 wire (cant afford a wideband currently- thanks to US dollar being so insanely strong)


Lastly does anyone have a copy of the Full MS sensor wiring diagram. (One that has all the wires labelled DB1 right through to 37)

[Cosmic_Eraser]

You can get the full pin layout for the DB37 connector from DIYAutotune's site.
MegaSquirt I / II Pigtail Wiring Harness DIYAutoTune.com
I would highly suggest you look at their pre-built pigtail harness. All the wires are labeled and it makes assembly much easier.

[Joe Perez]

Originally Posted by ogwazza

1. Do I need to add a relay for the fan output, or will the MS send enough power to the fan?

You need a relay. The PN2222A transistors used as MS relay drivers are rated for a puny 1A maximum collector current, and a fan draws considerably more than this, especially at turn-on.

2.As I have modded a 2nd hnd MS- how do I know where Iac1a and 1b translate onto the db37?

Well, all four IAC pins always show up at the same place on the DB37- pins 25, 27, 29, and 31. This is shown on the schematic: http://www.megamanual.com/ms2/megasquirt_ShemV3.00.pdf

I think what you need to know is what functions these pins are connected to internally, as on the 3.0 PCA they are not hard-wired to anything, they're just pads on the board. That means you gotta open the case and trace the wires connected to these four pads:



(the wire connections are probably on the back side of the board.)

3.I cannot get a 1n1002 diode in NZ at the moment to bridge across my EBC solenoid, so I bought a 1n1001 and a 1n1003- will either one of these work?

Yes. The 1N400x family are all identical except for their peak reverse voltage rating. The 4001 is rated for 50v, the 4002 for 100v, etc. The 4001 is more than adequate for a car running at 12-14v.

4.My MS diagram is limited, but it shows the O2 sensor as a 2 wire, mines only 1 wire (cant afford a wideband currently- thanks to US dollar being so insanely strong)

If you think the US dollar is strong now...

If you can find a bosch model 0 258 007 053 (aka 17053) wideband O2 sensor locally, you could try the JAW wideband: JAW (they're Canadian. )

When sensor-hunting, go to an auto parts store and ask for an O2 sensor for any of the cars on This List

Otherwise, for a 1-wire O2 sensor, the one wire goes to pin 23 of the MS.

I don't recommend it however, particularly on a turbocharged engine.

Lastly does anyone have a copy of the Full MS sensor wiring diagram. (One that has all the wires labelled DB1 right through to 37)

It's on the last page of The Schematic

[ogwazza]

Wow- I really appreciate all that help!!
Legend Joe Perez

Thanks again mate :-)