TPS shouldn't be used on the 90-93. Instead run a 470k resistor to ground.

Everything else looks right.

 

Is that due to the lack of analog measurement? just curious.

 

Yes the 90-93 is more of a switch.

You could wire up a Automatic TPS for a 1.6L Miata or Proto. But the
MS does Map accel and that works just as well. The only real need for a
TPS is for flooding problems which the Miata really doesn't have.

The 470K Resistor keeps the TPS from walking by itself.

 

Was this install done as a complete ecu replacement or does the MS function in parallel with the stock ecu?

I am asking because looking over the wiring diagrams, it seems like the ecu deals with quite a bit besides fuel/spark and a/c related idle control. I see a/c thermo switches and power steering pressure switches.

If you did do a complete ecu replacment, I would love to know how you delt with those stock ecu functions

 

It isnt running on MS yet, but it will be a replacement. My car is a barebones example. No AC, no PS, so the ecu will be relegated to handling just the Fuel, Spark and IAC functions.

Chris

 

Since the MS grounds 37 to turn the fuel pump on, couldn't you just connect 37 to the light green wire at the diagnostic connector?

 

Damn good question Private Pile!

I used a relay to jumper the two pins in the VAF together but I'm gonna try that.

 

If you look at the factory wiring diagram, all the switch in the AFM does is ground the light green wire from the ECU. Also, to test the fuel pump, you jumper the same green wire to ground at the diagnostic port. Once the green wire is grounded, it trips the circuit opening relay which supplies power to the pump. I haven't tried it yet, but it should go.

Edit to answer my own question:
Easier than the diagnostic port. Remove the kickpanel under the steering column and find the circuit opening relay. It has 5 wires coming out of it; blue/black, white/red, violet, black, and light green. Connect MS pin 37 to the light green wire and you're done. This is the same wire as the lt green wire at the MAF and diagnostic port, check for continuity if you're unsure.

 

In your last picture showing the board mods, your two red wires are parallel, not crossed. In this drawing, the yellow lines do cross, which results in coil A going to IAC1B and coil B to IAC2A, which is backwards. Just wanted to point this out for other folks. I just got things running yesterday thanks to this board and wanted to make things easier for others.

 

It doesn't really matter which way around they go as long as MSnSE/the loom connections are configured to match.

 

Yes, but if you were to cross the wires and follow the wiring guide in post #39, the coils will be switched. I know because that's what I did. When all I got was a backfire, I figured the coils were switched. Just hoping to smooth the road a bit more for others.

 

does this apply to 1.8 as well?? so you buy an assembled ms for 265 and what else do you need ? a list would help

 

Why exactly does D1 need to be removed?

Jim

 

It doesn't really.

D1 is on the board for a fuel only setup. For us to get spark we need to either solder a jumper across D1 or we can remove it all together. The advantage of removing D1 is that we can then re-use the diode to elimenate 'noise' for the PWM idle mod that some of us are running.

 

Here's what I found from DIYAutotune.com
MS130-C $325 (assembled MSV1 3.0 PCB)
MSStim21-C $75 (assembled megastim - optional)
MSHarness $68
IATwPiggy $21 IAT Sensor
38NPT-Bung_S $8 Bung for mounting IAT sensor (steel weld on, or JB-Weld on)
TuneCable $6.50
LC-1 without gauge $199 (Wideband 02 sensor plus wires - you can still view real-time AFR and datalog AFR through your laptop)
===================
$702.50

That's for the works, assembled but requries some wiring work, which I'm about to get.

 

or

MS130-C $325 (assembled MSV1 3.0 PCB)
MiataSquirt - $120.00
IATwPiggy $21 IAT Sensor
38NPT-Bung_S $8 Bung for mounting IAT sensor (steel weld on, or JB-Weld on)
TuneCable $6.50
LC-1 without gauge $199 (Wideband 02 sensor plus wires - you can still view real-time AFR and datalog AFR through your laptop)
===================
679.50

Plug in and turn the key!

 

Refer. pic of a 90 ecu for pin out lettering.

I'm starting back on the MS.

Chris

 

do i have to use ignitors if i use vb921 circut?

 

VB921's *are* the ignitors iirc

so if you're using 1.8 coils you don't need em

 

so my only other question is does n e one have a distributor wiring diagram.. i think it can trigger ms and run in wasted spark mode