MS3x harness wiring issues *cough* look Brain!
 

I recently had a shop diagnosis and then having to re-wire my whole car from the gas tank forward. Well they were at it, I ordered a MS3 and MS3x board and the MS3 and MS3x harnesses.

I thought they would wire it point to point ie yellow coolant wire to coolant sensor plug. I suppose I didn't make it clear that what I wanted because they cut the harnesses about 1 foot after the adapters and wired it to the stock harness.

This completely confuses me because I thought there were a few wires, particularly on the MS3x harness, that needed to be wired directly to other sub-harnesses, like the injector/coilpack harness.

There's this rat-nest of wires soldered and cripped to the wires and still connected to the stock ECU plugs. They ran the car on the stock ECU, so it looks like they ran two different wires out of one input wire. One to the stock plug and another to the MS3x plugs.

I really wish I could of done all the wiring myself but I didn't have the time or space to do it at the time. I'm now stuck re-wiring a lot of shit myself anyways :vash:

What I'm asking, is if there will be any issues with the MS3x harnesses being wired to the stock harness. I'm was really looking forward to having every wire labeled every three inches, but now I get to chase wires all the way back to the computer to see what they are a lot of times :( (I'm not 100% they followed the correct wiring diagrams)

Car ran for 20 minutes or so, ran rich as hell, and wouldn't idle for the first minute or so. Got it home for the night, went to sleep. Got up the next morning to head to the Mitty, started it, ran for 20 seconds, sounded like shit, wouldn't idle and died. Hasn't started since. Swapped the plugs thinking it flooded the engine, still nothing. Found out my coolant sensor wasn't calibrated, tried to calibrate it, still reads 180.0 F all the time :(

Ended up finding out it was running off the stock o2 sensor and not my wide-band :vash:. wired that up today. Still tracking down coolant sensor issues, hoping cranking pulse-widths has something to do with it not starting.

I could of fucked up the wiring myself for A LOT cheaper :giggle:

Plz halp!

use the spark and fuel test mode. make sure everything is firing the way it should.

dont have anyone cut wires.

Is this test mode available in TS?

yes, one of the last tabs. kinda tricky to get it to work.

12345 TAB burn.....

Seems too easy, I think something will explode, especially knowing my car.

What's next if the test mode checks out ok?

Reading thru some ms3 docs, and it says the normal bias resistor value for CLT(R8) is 2490 ohms, although they have a GM sensor listed. Did a quick google search and found someone getting a of 2490 ohms at 68 degrees F.

Is 2490 standard for both the CLT and Air temp sensors?

Trying to double check my calibrations.

Also, the internal map/baro sensor on the ms3 is mpxh6400, right?

yes, because that is the resistance of the physical bias resistor in place on the PCB.

If you have the 4 bar, yes.

Well, I did test mode for spark and got nothing. Also checked for spark the old fashion way, nothing. I'm getting fuel though, I can smell it on the plugs.

Still can't get correct reading for clt, keeps reading 180.0.

It's weird that it ran for 20 minutes or so on the drive home, then wouldn't start the next morning, no changes made :(.

then get composite log, see if CAS is syncing.

I'll have to try that later, I gave up and left the garage, lol.

Bump....

Haven't ran the log yet..... but let's say the CAS is out of sync, I don't even know where to start with all this rats-nest wiring, lol.

I'm really tempted to just wire up the 99-00 head without the CAS.

So doing some research today, what all is involved in ditching the cam angle sensor and going to a crank angle sensor. Since I have 99-00 head and 01 block(complete NB motor) and the MS3 doesn't NEED the CAS(cam).

My initial thoughts are to just take off the cam angle sensor, wire up the crank angle sensor, and then change spark mode in TS from 4g63 to 99-00 miata. But I'm not sure what to wire up the crank angle sensor to. I did manage to get back the rest of the cut-up harness, so I do have a lot of extra wire :bowrofl:

I also can't remember if I kept the trigger wheel on the 01 block, don't think I would have any reason to take it off though. But maybe I should get TSE's 12-tooth for better resolution :idea: Guess I would need to do some research on which spark mode to run with the 12-tooth though.

The NB triggers could provide a bit more accuracy than the NA CAS does, but I think you'd be better off sticking with what you have for now. IMO, no use in adding variables at this time. Later on down the road when things are sorted and sailing is smooth, then go for it then. Sounds like a good Saturday project sometime over the winter.

Wouldn't you also need to switch to NB circuits to use the NB sensors? That might add in another point of failure for now.

When I went from CAS to NB sensors all I did was put on new pigtails and flip the trigger option in MS.

Yeah, I thought of that too Ben, but this was going to be a solution to the problem of the NA CAS not syncing up. The shop had a lot of problems with it not syncing up originally. That's the main reason they wired it up to be able to run the stock ECU.

lars, I have the NB sensors, I figure if it's wired to the right pin-outs on the board it should be fine.

Fatkao, you make it sound real easy, lol.

I need to find the little cap that originally goes on the back of the exhaust cam though, no idea where I put it :(

Which pin # is the CAS on the MS3x board?

We mentioned in SC2 but I was distracted, lol.

In theory, the NA CAS and the NB crank and cam sensors are electrically identical. They both provide a pair of what's known as "open collector" outputs, which is a switchable closure to ground. You apply an external pullup (through a resistor) to raise the voltage on the line, and then the sensor pulls it down to 0 to signal an event.

In practice, the two cars do seem to have some minor differences insofar as the cleanliness of the signals, what the edges look like, etc. Even from one NA to another there is variation.

Also, bear in mind that the two families of circuits (on the MS side) were developed by different people at different times. The original input circuit (designed on the MS1 with an NA) was simply thrown together to be cheap & easy. Later, during MS2 development (and then later still, trying to get the damn thing to work) considerably more thought was put into it.

Ideally, what we think of as the "NB-style" input circuit (the one using double-comparators), or the even more modern MAX9926-based circuit should be used on all cars with open-collector sensors, be they Miatas or McLarens.

Sadly, the creators of the MS3X board chose to use the old developmentally-disabled version of the input circuit (the one using the MCP6002 op-amp that's been around since the days when they used green PCBs) in the new product, but it seems to work sufficiently well.





In the "standard" build, the crank signal goes to pin 24 on the main connector, and the cam signal goes to pin 32 on the X connector.

This page describes the wiring and configuration for an NA: http://www.msextra.com/doc/ms3/4g63.html (The NB will be identical in terms of wiring, but use a different software config.)

Thx Joe! I think that info will help me trouble shoot this problem a lot :).

I'm really thinking about ditching this car all together, transferring some parts over to my 94, get some Clubsports, and have a stupid fun car that'll be slightly competitive in STR.

The 94 will need a freshened up engine, which I hope to source an 01+ engine, and run a MS in the stockbox. Wondering if the VVT controller could fit in there as well or if it'd be easier to do a MS3x in the stock box. Or say ef it all and get a 99-00 engine with a MS2 in stock box.