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Old 07-24-2008, 06:34 PM   #21
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Looking at my wiring diagrams (why are they always different lol) the CAS ground meets the light green black at the ground stud near the TB. Even with the LGB removed from the stud its showing GND so somewhere somehow its connected to something not on the diagram.

If it comes to running another wire then I think I'll give in and run hose to the map in the case.
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Old 07-24-2008, 06:55 PM   #22
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Is your stock ECU still installed? If so, it's going to ground through pin 2F.

That really is all. This is a US-spec drawing, but I can't imagine the UK cars are any different in this regard:


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Old 07-24-2008, 07:04 PM   #23
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Page 9 of this shows my cars wiring ***** on perfect.

http://www.madracki.com/miata/images/wiring/94sys.pdf

The stock ecu wasn't installed when I tested it but the MS was 2F shouldn't be connected to anything but for all I know it could have been touching the case. I'll pull it tomorrow and check again before going to town on my wiring harness to find where this thing goes to ground.
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Old 07-25-2008, 04:58 AM   #24
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Once again Joe you right me wrong.

I pulled the MS and the ground went away but unfortunately the CAS is on that same ground :(

My only hope is to find this connector


This is where the GNDs from the MAF, CAS and some sort of shield around the sig from the maf all join together to the ltGB wire.

EDIT: it looks like its labeled as X-35 (not the prototype for the next generation of STOVL fighters but a plug I hope) does that superior diagram of yours also list its location somewhere?
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Old 07-25-2008, 11:49 AM   #25
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It's not an STOVL, it's a low-observable interceptor.

Seriously, though. Unfortunately I do not have the whole '94 manual, only the three pages of it that pertain specifically to the ECU wiring. I don't have the ground distribution schematic or the physical connector map. From experience, those X-ground unions are typically a rectangular plastic bit, black in color, and distributed pretty randomly around the engine bay. They often have a metal tab on them that both mounts them to the chassis and makes an incidental ground connection as well.


I really do encourage everyone to purchase the official Mazda service manual for their car is undertaking any kind of serious wiring work, as they contain some truly amazing diagrams showing the location of every single ground point, harness interconnect (that's what the X's are) and end-termination. Here's an example from the US-spec '92 manual, one of many for just the under-bonnet wiring alone:

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Old 07-25-2008, 01:08 PM   #26
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I have the complete '94 shop manual and can try looking it up and posting a scan later this evening, if you haven't found it by then.
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Old 07-25-2008, 04:13 PM   #27
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Thanks for the offer Scott, I have given up on using the spare pin, turns out on my fucked up Jap import it grounded to 2D!? I have run one more piece of wire and its now working nicely.

LC-1 is hooked up and I gave her a crank....no dice. I have spark and I have fuel smell from the exhaust. No coughing no backfires notin.

I havn't set up the base timing yet as my friend has run off with my timing gun but how far out could the MSPNP base map be?
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Old 07-25-2008, 04:39 PM   #28
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When I first fired up my MS1 on the original CAS using the DIY wheel decoder settings, my two spark outputs were reversed. The way they have that thing set up, SparkA is 2&3 and SparkB is 1&4. Try revering the two ignition primaries, or swap the plug wires between the two coils, and see if that gets you anything.
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Old 07-25-2008, 05:28 PM   #29
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I swapped the coils still no go. I'm going to use my magic neon spark plug hats to make sure I have sparks on all my coils.

Could my timing be so far out that it wouldn't start? Just to make sure I still have working coils I stuffed the old ecu back in and it fired up first time (even though I forgot to plug the MAF back in! Stock ecu works with map and AIT who would have thought).
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Old 07-25-2008, 05:54 PM   #30
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I suppose it's possible. The default MSPNP msq that I just downloaded has the trigger angle at 65 and the addition at 22.5. Interestingly, the program tells you not to set the 22.5 unless you need over 90 total, but 65+22.5<90. Try changing the 22.5 to 0 and see if it fires. With the addition at 0 I still had to add back some trigger angle though, after I got it running. But I wasn't interested in messing around with it to see how far off it could be and still run, so I don't know if that could be wholly responsible for your trouble. Is your base timing in the vicinity of 10* on the stock ECU?
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Old 07-27-2008, 08:56 AM   #31
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UPDATE:

We have lift off!

Joe, The sparks were inverted. Scott, changing the addition value to 0 got it almost perfect. Thanks one and all.

I did spend 1/2 a day getting it to fire though. Turns out engines really like fuel. So when I connected the FP wire it caught first time. I am such a tool.

The idle is still a bit bouncy but I havn't started tweaking just yet.

How do you attatch logs?

Edit: Strange symptom now. A few seconds after starting the engine I get a strange harmonic drone from the idle valve. When I changed the frequency in the idle settings the drone changed pitch. I could get my megasquirt to play god save the queen like the Renault F1 car on Top Gear. Any idea what is causing this? Whilst its making this odd noise it also idling around 600-700 rpm even though the slow idle is set at 1000 rpm.

Last edited by Duckie_uk; 07-27-2008 at 04:54 PM.
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