Miata Coil On Plugs

"mXxxxXm24 /O/ /O/" (mxxxxxm24)
05/31/2019 at 18:05 • Filed to: Arisu, Miata, Miatafications, coil on plugs, DIY

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.

DISCUSSION (18)

Cash Rewards > mXxxxXm24 /O/ /O/
05/16/2019 at 22:00

I have no experience with that, but do like fab9. Got my suspension and seat from them, and they’re fighting to get me my seat mount. Pci got a bad batch apparently, so had to redo a bunch of orders. Then the “it’ll ship this week” starts from pci, and now two weeks after that I got no evidence it shipped. But I asked fab9 to see if they could get pci to expedite shipping when they do ship, and they’re going to bat for me.

Let me know how this works for you, though. My tundra runs coil on plug, and I've seen this setup before. I gotta do plugs next year, probably.

mXxxxXm24 /O/ /O/ > Cash Rewards
05/16/2019 at 22:07

For sure man. I’ll post something after I get a chance to install them. I’m hopeful! And yeah I like fab 9. I got my pci race mount from them. Pci seems kinda hard to deal with. I tried to let them know something they could add to their instructions and they acted like I was bothering them by telling them how for my specific model the relocation of the factory seatbelt was completely unnecessary. Said they didn’t really mess around much with miatas anymore iirc. However their mount is perfect for what I needed. Glad to hear you went with it!

gettingoldercarguy > mXxxxXm24 /O/ /O/
05/16/2019 at 23:33

What year Miata is it?

mXxxxXm24 /O/ /O/ > gettingoldercarguy
05/16/2019 at 23:39

‘96

sony1492 > mXxxxXm24 /O/ /O/
05/31/2019 at 18:18

A standalone should be able to control a stock ignition system, is the miatas system special? Can you tune timing with the ignition module, it sounds like its acting independent of the ecu.

sony1492 > mXxxxXm24 /O/ /O/
05/31/2019 at 20:55

Th e stock ecu has the ability to control the COPs?

Brickman > mXxxxXm24 /O/ /O/
05/31/2019 at 21:17

I’d put some wire cover or sleeve so you dont risk melting the wires on the valve cover. Even make it in different colors.

Future Heap Owner > mXxxxXm24 /O/ /O/
05/31/2019 at 21:22

Nice work! I’ll be interested to hear how much of a difference you notice.

mXxxxXm24 /O/ /O/ > sony1492
05/31/2019 at 21:48

To be honest I am not sure. I am very inexperienced with tuning. I was told that cop’s were necessary to be able to control them independently and I assumed that was with any aftermarket ecu, but I could be mistaken. You can’t get independent control of them with the factory ecu though, I know that.

mXxxxXm24 /O/ /O/ > Brickman
05/31/2019 at 21:50

I was kind of worried about that, but figured they shipped them that way, so they’d be fine, but I’m on the fence about that! What kind of cover would you use?

mXxxxXm24 /O/ /O/ > sony1492
05/31/2019 at 21:54

Oh and you adjust the timing with the cam angle sensor, by rotating it slightly. I advanced mine to 14 degrees (from 10) to increase torque in the mid range.

Brickman > mXxxxXm24 /O/ /O/
05/31/2019 at 22:26

Like this will be good. Use electrical tape or zip ties around where each wire goes to the coil/plug.

https://www.amazon.com/Flexible-Polyethylene-Wire-Diameter-Black/dp/B00DP3K8A6

sony1492 > mXxxxXm24 /O/ /O/
05/31/2019 at 23:39

Sorry I asked the same question twice, my internet doesn’t pair well with kinja.

Coil on plugs arnt necessary for sequential ignition but they do give you the ability to have good spark at rpms that require more dwell(time to charge the coilpack).

Thats cool that you can somewhat adjust timing without going crazy on engine management. S ounds like the cars ready for some boost down the line!

mXxxxXm24 /O/ /O/ > Future Heap Owner
06/01/2019 at 01:34

Yeah so far it’s been a vast improvement, but I also needed to change the plugs/wires anyways lol

mXxxxXm24 /O/ /O/ > sony1492
06/01/2019 at 09:49

Oh ok that’s a plus! I have a lot to learn about tuning lol. As for boost... I don’t plan on it currently. I have much to modify and pretty much been going for lightweight na power. More power is always so tempting tho!

mXxxxXm24 /O/ /O/ > Brickman
06/01/2019 at 09:52

Thanks! I’ll reassess the wiring soon

sony1492 > mXxxxXm24 /O/ /O/
06/01/2019 at 17:24

The simplify and add lightness approach is usually alot more reliable, looks like your headed in the right direction.

mXxxxXm24 /O/ /O/ > sony1492
06/02/2019 at 21:32

Thanks, th at’s what I’m hoping! I need reliability with this being my daily and only car.