96 with 99 head swap
 

Hey guys,
​​​​​​I'm off to a slow start on my project, but I did pick up an AFR and want to megasquirt my car. I particularly want to do this because the project that I picked up is a 96 Miata with a 99 head swap and the car idles really rough. I figured if I can get the swap tuned with a megasquirt unit, it should run much more smoothly. However, I am not sure which megasquirt configuration I need to use.

I want to do a DIY build of megasquirt, but do I use the 96 wiring or do I use the 99 wiring? I have tried to research this and have come up confused and empty handed so any and all help is appreciated

It would probably be easiest to use the wiring that's already on the car. A DIYPNP is a pretty easy way to set this up if you want a build it yourself kit.

sorry, I should clarify. By "wiring" I meant the jumper settings for DIYPNP. Do I use the 96 jumpers or 99 jumpers?

I'd solve your issues first, it shouldn't idle roughly.

Maybe the VICS wasn't properly set up, and the OP wants to use a MS3 to get it working? :dunno:

Anyway, as far as wiring, they say the rule of thumb is that the wiring follows the chassis, not the engine, so you'd build a box for a '96, not a '99.

perfect. Thanks.

Check your coil packs?

Its kind of weird. I need to give it gas to start, but even if I keep my foot steady on the accelerator, it revs super high, and then comes back down and does that several times. I figured it had to do with weird AFR readings and figured I could have ms fix it. Bad train of thought apparently?

Yes. You have other issues, look all over the manifold for loose, missing or cracked hoses.. Check for vacuum leaks. Is the idle air hose connected?

Post pictures, tons of them. Front, rear, sides, angles, etc., nice clear pictures. Makes it easier to spot the obvious.

Match the jumpers to the year of the wiring harness.

Sounds like 2 issues. Needing your foot on the accelerator to start is one, not sure what. The high revs after it starts and oscillation sounds like a vacuum leak. There's about 6 dozen vacuum barbs on the VICS (99-00) intake manifold you probably don't know about, the one I always forget is on the bottom, between #3/4 runner. I think it's supposed to feed the VICS solenoid.

Thank you everyone for your input! Sounds like this car is going to be more problems for me before it gets to be fun to drive. Just bought an assembled MS for a decent price, but sounds like it'll be a bad idea to install until I figure this thing out (thanks Curly). I appreciate all the helpful comments, but I will start a new thread in general chat after I've tried a few things to figure out my issues just so people running into similar issues to mine can follow it properly in the future. Thanks again guys!