Seq inj + Ign question
 

With a MS3X/MS3Basic, I wire up the ign and inj as ACDB over 1-2-3-4, correct?

Thanks guys!

No.

The firing order is 1-3-4-2.

So, the correction is:

A = 1
B = 3
C = 4
D = 2

Or stated another way:

1 = A
2 = D
3 = B
4 = C

or

Alpha = I
Bravo = III
Charlie = IV
Delta = II

Or

α = H
β = Li
γ = Be
δ = He

I have to admit that this made me laugh my ass off Joe.

All right.

Last issue before I have everything wired up - I'm done with everything but the injector harness.

I used to have Green Wire to Injectors 1+3, and Yellow Wire to Injectors 2+4.

I know I want 2D and 4C, but where do I connect Green and Yellow to now/how do I tell which is A or B?

I'm assuming Green is A, and Yellow is B?

And you've lost me with this discussion of a Green wire and a Yellow wire.

What, specifically, are you trying to do?

I'm trying to figure out what wire goes to what for A/B on the injector end, Joe.

Originally, I had it wired for batch injection, one wire to 1/3, one to 2/4. The only problem is I'm not sure which is which for purposes of rewiring this (custom) injector harness - I'm done with CD on the injection, ABCD on ignition, and all the other rewiring I needed to do, I just have to figure out which is A and B for injection. I know which goes to 1234 on the injectors, just not which is which on the stock plug which is where this custom injector harness plugs into.

what model year? it doesnt really matter...color is meaningless.

91

EDIT: You and brainey posted while I was typing this. So you can ignore the first part. I'll leave the original message intact for posterity. Since I don't know what modifications you've made in your "custom injector harness" I can't address that side of it.

Ok, I'm going to assume that you have a '94, since you haven't told me otherwise and it's not in your sig. Here's the wiring of your injectors at the ECU connector.

https://www.miataturbo.net/attachmen...1&d=1364176162

And here's the pinout of the MS3X connector, with regard to the injectors:

https://www.miataturbo.net/attachmen...1&d=1364176309

ECU pin 2U (inj 1) to MS3X pin 19 (inj A)
ECU pin 2V (inj 2) to MS3X pin 10 (inj D)
ECU pin 2Y (inj 3) to MS3X pin 16 (inj B)
ECU pin 2Z (inj 4) to MS3X pin 13 (inj C)

Got the wiring for a 90-93 offhand, Joe?

I could backtrack through the harness to find what color is what on the wires if I could find out what was A and B for colors on harness wiring.

Logically, I'm thinking 1+3 is A, and 2+4 is B.

I'd test directly through the harness to the MS3 connector, except that Rev uses non-standard connectors for the MS3X aspect...

https://www.miataturbo.net/attachmen...1&d=1364177608


Ideally, they'd have been connected such that 1/3 = A and 2/4 = B, assuming that only channels A and B were used (more on this in the last paragraph.)

However, the banked injection mode on the MS does not properly emulate the OEM design, as the OEM ECU had only one squirt per line per cycle. Thus, there is no absolute standard for banked injector phasing, since it will always be "wrong" no matter how you do it.

I created a thread about this here: http://www.msextra.com/forums/viewto...47229&p=340885 In that thread, I show scope captures of OEM banked injector phasing vs. several different MS configurations. It is my opnion that 1/3 = A and 2/4 = B is the least incorrect way to wire banked injectors to an MS, assuming you are only using the A and B channels.

The actual correct way to do it, if you want to match the OEM design, is to wire 1/3 = D and 2/4 = B, however this is a more advanced topic than you probably care to be distracted by right now.

TL;DR: You need to trace the wires to be sure.

Yellow should connect 1+3 in the stock wiring, and yellow/blue for 2+4 correct Joe?

Thank you, I can easily track that back!

sigh.

god forbid you look at this:

https://www.miataturbo.net/attachmen...ine=1364219967


this question was answered in 2010.

But if you're wiring for seq, it doesnt mater which of the injectors goes back to the oem wiring so long as they all go back to the MS in the correct firing order. I'm almost positive I have inj C and D going from my MS through the OEM wiring for some reason.

^ THIS

There is no single, unified standard for converting a 1.6 engine to full sequential. When I did mine, I abandoned the two stock wires and ran a new sub-harness with four new wires (plus two more grounds, just because I like grounds.)

Well, I may end up doing that yet Joe - except I have to figure out what pins are what on Rev's MS3.

Thanks guys. Plugging everything up and preparing to start the sumbitch today.

Understood. Which is why I said you'd have to trace the wires.

For all I know, it's entirely possible that your two injector channels are connected to INJ I and INJ J, which are the MS3 nomenclature for the two injector channels on the main board, as opposed to the MS3X board. You won't know until you trace the wires.