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Old 04-29-2008, 01:17 PM   #1
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Default Help me choose my MSPNP

Here's the deal:

I have a 91. I will swap a 1.8 but I don't know what's the year of the engine.

Wich MSPNP do I need? And what's the difference between 90-93, 94-95 and 96-97 version?

Thanks
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Old 04-29-2008, 01:19 PM   #2
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the one that fits your harness and sensors.
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Old 04-29-2008, 01:19 PM   #3
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You need a 90-93. You're just putting a different engine in everything will be the same in the car and the wiring except you might extend some things and add a variable TPS.
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Old 04-29-2008, 01:25 PM   #4
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Your best bet (least impact to vehicle wiring) is to get the '90-'93 MSPNP, and transplant the engine harness (injectors and sensors) from your 1.6 onto your 1.8.

This way, the MSPNP will mate perfectly with your old ECU harness, and that will then mate perfectly with your engine harness. The differences I can think of regarding the 1.6 vs. 1.8 engines harnesses:

TPS: simple, well-documented cut and splice
MAF: who cares?
Ignition coils: slightly more complex. You can either use a bracket to transplant your 1.6 coils onto the 1.8 engine, or do some creative splicing involving the coil plugs cut off the 1.8 harness and spliced into a length of wire that goes to the stock 1.6 igniter location. Not really difficult, just more involved.
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Old 04-29-2008, 01:42 PM   #5
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Thanks for all the answers. I plan indeed to flush the MAF and the TPS was in mind too. I'll check out more deeply the coil thing.
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Old 04-29-2008, 02:28 PM   #6
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Quote:
Originally Posted by Joe Perez View Post
You can either use a bracket to transplant your 1.6 coils onto the 1.8 engine, or do some creative splicing involving the coil plugs cut off the 1.8 harness and spliced into a length of wire that goes to the stock 1.6 igniter location. Not really difficult, just more involved.
Or just convert to COPs.
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Old 04-29-2008, 02:33 PM   #7
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Quote:
Originally Posted by Dark Wanderer View Post
I'll check out more deeply the coil thing.
The difference is simply that the 1.6 used an external ignitor and had a single three-wire connector to feed power and two triggers to the coils, whereas the 1.8 engines use coilpacks with integrated ignitors, and thus have no ignitor connector, and two separate coil connectors. Depending upon the year, the two coil connectors are either four pin (+12, GND, trigger, and tach out) or three pin (+12, GND, and trigger. Tach comes from the ECU)

Either way, assuming you get the engine harness along with the engine, you can splice the new connectors into your old car. +12 and trigger are both self-explanatory and present at the igniter connector. Ground runs straight to the head. If you have a '94 or early '95 engine with the four-pin coils, combine the two tach outs and feed into the tach wire at the igniter. If you get a later engine with three-pin coils, you can either diode-isolate the two trigger lines and use them to drive a transistor to create your tachout, or you can take it direct from the Megasquirt (modification required).

Oh, your CAS will move to the exhaust cam. Same connector, but you may need to lengthen the harness a few inches.

If you choose to swap the coils, FM sells a bracket to do it: http://flyinmiata.com/index.php?dept=67

You do not need the throttle body adapter from that page- you're going to keep the 1.8 TB on the engine.
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