1990 Eunos Roadster MS2 V3.0 (lost sync 39)
 

Hello everyone! I am a long time guest, first time poster.

I own a 1.6 1990 Eunos Roadster (imported from Japan into Ireland sometime in 1997). It has been my daily for 2 years and the hardest thing I've done prior to this was a TB change.

A few month ago I took the car off the road to start a turbo conversion.
I got a new, pre-assembled MS2 V3.0 with an added ignition board (it includes Spark A, B and C wired to D14, D16 and D15 respectively). The ignition board brings the spark outputs to a second 37 pin, female D-sub. So far so good (see below).

https://lh3.googleusercontent.com/bp...=w1218-h685-no

https://lh3.googleusercontent.com/dd...=w1218-h685-no

My guess is that this circuit is a variation of the one shown in the "MS2V3.0 Hardware Manual" (Section 5.3.1.2). The only thing that seemed to be missing is the R43 / jumper (I have added the jumper since).

There are a few jumpers present at the bottom of the board (purple and red, photo below). My guess is that these are used to supply 12V to the ignition board for an aftermarket tachometer (TACH_IN/OUT above in the photo).

https://lh3.googleusercontent.com/d8...=w1218-h685-no

Since my car is a 1990 and has the Mitsubishi type CAS, I followed the manual and modified the board to get the 2nd CAS (CMP) signal in. I followed section 5.2.14.2 of the MS2V3.0 manual.

I did the following:
1) OptoIn ---> SPR3
2) OptoOut ---> JS10
3) Jumper XG1 ---> XG2
4) Installed 470 Ohm (1/4 W) resistor in proto area connected to 5V, then
5) 470 Ohm in proto area ---> OptoIn
6) Removed C30 (also checked R12, it was 390 Ohm, as required)

https://lh3.googleusercontent.com/7h...4=w386-h685-no

https://lh3.googleusercontent.com/o0...E=w386-h685-no

All seemed well until I hooked the ECU to the car and tried to start it.
First problem is that I am not getting any spark. I tested the coil connector resistances between the red-black and white-black and I'm getting 1.1 Ohm. The optimal values here should be between 0.75-0.94 Ohm. So I think the coil may be in a bad way. More worrying the the intermittent RPM signal.

https://lh3.googleusercontent.com/D9...=w1096-h685-no

During cranking I can also hear the fuel pump relay switch on and off in sync with the intermittent RPM signal.
So here is an open ended question, what am I missing? Is this a wiring issue, or a settings issue? Is the CAS bad? The lost Sync reason is #39, which just states 4G63.
The tune and .msl files are attached. Any help would be appreciated!

I seemed to have resolved the issue.

First, I had the tach output "ON" and set to JS 10. I think this might have been interfering with the RPM signal. When I turned off the Tach output, I got a sync error 38 (instead of 39).

I then messed around with ignition settings. Set them like so:

https://lh3.googleusercontent.com/RI...=w1096-h685-no

The only thing that I changed from the previous settings was setting the "Flip polarity on cam" to "Inverted".

Result:

https://lh3.googleusercontent.com/WS...=w1096-h685-no

Still no spark though. I can see the LED 14 and 16 flickering during cranking, but no spark can be observed when a plug is connected to the coil but out from the engine.

So, a small update. After reading various tidbits on this site and others, I put the ECU into test mode to see if I can register any voltage on the Spark A or B channels and GND. The short answer is no.....as long as the harness was plugged in that is (the spark outputs are on separate harness on my setup). As soon as I unplugged the harness, I could read a voltage coming out of both irgs14c40l transistors on that expansion board. As I reconnected the harness, voltage dropped to zero on both channels again.

Is this normal behavior?

I will try and find a new ignitor, see if that has something to do with it.

Ok, I think I might have figured out what I am doing wrong RE the no-spark issue.

That ignition expansion board is the variation of BIP373 high current output mod. The board uses the IRGS14C40L transistors instead of BIP373. I have always assumed that the Spark A and B from that board need to be wired to the mx5 ignitor. It took me a few times reading through those sections of the manual to realise that these outputs need to be connected directly to the coils....(I hope....).

This thread: https://www.miataturbo.net/megasquir...uestion-50353/

So now a dilemma... Either delete the expansion board and modify the ECU to run with a stock ignitor

or

keep the board and faff about with wiring in the bay to get the 12V to the coils plus the Spark A and B from the MS2.