Coil on Plug System

[Keith Jones]

Has anyone tried a Coil on Plug system on their NA1600?

I have fitted a set of Toyota COPs and used the instructions on the Miataturbo forum. However, the tacho doesn't work now, and there is a hint of a misfire.

From the very long thread (64 pages) on the forum, it looks like aftermarket ECUs (I've got an original MiataLink circa 1992) ) need a 1k pull up resistor between the 12v feed to the coils and the tacho lead from the coils to make the tacho work. I've just tried this but now the car won't start and backfires in the inlet as if the ignition timing is way out.

Help!!!

[sprsta]

i think the resister is for if you have a megasquirt

here is another write up on cops if you havent seen it already

http://www.miataturbo.net/forum/t18937/

[Keith Jones]

Thanks sprsta.
Lazzer's wiring diagram for both 1.6 and 1.8 cars, which seems to have become the guide for most people in the US converting to COPs, shows the resistor for Megasquirt.
Initially I didn't put the resistor in, but the tach didn't work, and the engine didn't idle quite as smoothly as with the normal plug leads and coils.
Hunting through the Miataturbo.net thread I found a post from a guy with a Link saying that he had put a resistor in to get his tach working, but this doesn't appear to be the solution for me.
The other concern I have is that the dwell time for the Link might not suit the Toyota COPs, which may be the cause of the lack of smoothness of idle. Unfortunately my Link doesn't have adjustment for dwell time.
I may have to put the COPs away for now and hope the normal coils and lead system can handle the increased boost I'm planning.

[sprsta]

ive always thought that holden commodore coil packs would be a good upgrade those things can give a huge kick

[Euen]

Keith

As far as the dwell is concerned, there is a circuit that was developed to adjust the standard MX5 dwell which I think is about 3.5 to 2.8 or there abouts for the Toyota cops. Fortunately I was able to do this on my Link.

Details of the circuit are on forum.miata.net, search on "My Toyota COP dwell reducer circuit" in Power Mods. I believe that Boundary Engineering will sell you the cicuit built up.

Does the FM Link not have a tacho dive off the computer that you could use.

Also, there was a recommendation to fit a 10,000uF capacitor across the 12 volt supply close to the coils to try and overcome some of the voltage drop across the coils. I think this was probably for people running on standard ECUs which were a bit fussy about the voltage drop.

Give me a shout if you need a hand.

E

[sprsta]

heres the ecu pin out