Well, I had been having ignition breakup on my nonturbo 88 GTU for a while now. The AFR's on my wideband were jumping around (not smooth) and my recent dynosheet showed some breakup as well. I changed plugs and wires, and made sure my timing was dead on, but that still didn't fix it.

I decided it had to be the coil or the ignitor in my leading coilpack. I'm aware that these cars have a pretty strong ignition system, but after 155k miles things wear out. I checked the resistance on the coil part per the FSM. I didn't have the special tool needed to check the ignitor, and Mazda wanted $75 to do it. A new ignitor from Mazdatrix is like $280, so I decided just to get a regular old MSD 6A box (none of the expensive fancy ****) for like $160 to see if it would help. I didn't want to hassle with used parts of unknown condition.

I installed it today and did a second gear pull on the street, and the AFR's are holding much more smoothly. It used to be that at about 5k it would jump all over the place, but now it gradually richens up (stock ECU currently with no SAFC for now, I'm about to put my megasquirt in and get it tuned) like it should. My idle is a little bit smoother as well.

So for any of you with ignition breakup, I recommend installing it. It's easy, except for the two really short wires you have to splice into the input wires on the MSD box.

 

I installed mine and think I wired it wrong. I got a lack of power. Like the timing was 20 off or so. Could you spost how you wired it please? Or take pics of wiring?

Ill try to explaine mine.

Big Red = Positive (fulltime power)
Big black = Ground

White & Black from MSD go to Ignitor
the other two from MSD go to existing wires that where removed from ignitor to create a loop into the msd.

is that how you did it?

 

FC3S pro has a write up; I used that. I don't have a link right now b/c i'm at work. It sounds like you messed up that white wire.

I'm not sure, but your timing could be off 20 degrees I think if your leading coil wasn't firing at all. I knew mine was working b/c I uhh accidently forgot to plug the wires back into the coil, so when I started the car after installing the box it sparked viciously.

from memory:

did you splice the thin red MSD wire to the cream colored wire from the ignitor? then I think the thin white wire from the MSD goes to the black wire on the ignitor (cut the ring terminals off those two wires from the ignitor.

Then there should be like an orange output wire from the MSD that goes to the positive (the one that the cream wire used to go to) terminal on the ignitor and I think a black one bundled with it that goes to the negative.

If you looking at the leading coil from the driver side fender, I believe the original cream wire (positive terminal) is on the right and the black wire is on the left.

Try to find that writeup, it should explain it.

 

Yeah, I went to the write up. It could be it is bad. My coils work fine, no prob there. Did you hook the old wires that ran to the ignitor back into the MSD?

 

I did it exactly the way the writeup says. Exactly. Oh and I had a brand new box, not used.

 

lol... ok. THen it is the box. I have another ill try. Thanks for the help!

 

I will have to try that...I am having some massive ign break up on my TII wiht a Haltech...

Anything above 5psi and higher than 5000rpm....the break up starts...the tach needle drops really fast....going to try that.

James

 

Sounds wrong...

At the very least, I think it's thin white and thin read to coil?


-Ted