I had zero experience with coil on plugs, but I got a set from Fab 9 hoping this will improve ignition efficiency and maybe solve my on going intermittent rough idle. The coil packs on Miatas are kind of a weak point, on some models more than others—I’m looking at you ‘99.
Install was about as difficult as swapping out plugs and wires, but with the added task of removing your stock ignition coil and mounting your new ignition module to the firewall. It took me a little bit to figure out where to plug in the new module, because the instructions didn’t really help. However I read on a forum, that after plugging it in you would end up with 3 unused factory connections and that gave me enough of a clue.
Once I had everything clipped into place, I then found a spot to mount the ignition module to the firewall. I chose to use stainless bolts I had leftover from my de-airbagged lid project. This choice meant I had to mount somewhere that I could access from both sides of the firewall and have enough slack for the wiring. I found a spot nesting it right behind some hardlines going to the abs system. hopefully those won’t vibrate and damage the module?? I can’t imagine that would be the case, so there it will stay for now.
I drilled the holes through the firewall and bolted the module in. It was a weirdly tight, but perfect fit. Like my drill and screwdriver each just fit between these two hardlines. Not sure about cutting into the stock wiring harness, I left the three unused clips (the two that went to the factory coil and the one that connected those to what is now clipped to my new ignition module).
There you have it! It was that easy on my ‘96. Earlier models require an additional adapter for the speedometer and installation may vary. This is as I understand it a must do for most efficiently running an aftermarket ecu, in order to have control of individual spark plug firings, but if you’re like me and you have the stock ecu (and you hate money) you can drop 5lbs off the engine and have a smoother more consistent spark, idle, and rev range.