Just wondering myself if there is a reason to use two ignition modules instead of just one.

 

Yeah there is a good, compelling reason.

 

You need to have an ignitor for each coil, unless you distribute the spark another way, I.E. the stock distributor.

But doing that wouldn't be direct fire would it?

So yes, Direct fire = coil with dedicated ignitor.

 

Well here is what I'm looking at, given that from what I know about batteries that the only purpose of the relay is for you to flip a switch and ground out the coil so it would basically be battery shorting to itself, but that's terrible for the battery and will kill it after a short while. I just used the positive connector for the coil power off the wiring harness and I'm pretty sure that only has power when the car is switched on anyway, however if someone knows otherwise then feel free to correct me. For quick reference I'm in an 83 GS so 12a and after I flipped the leads today from what the diagram says for the dizzy to the ignitor and that worked out alot better for me.

 

Measure the switched voltage through your terrible stock ignition switch vs direct from the battery and you'll see why you want it direct.

 

no, a relay closes a circuit. it can be on ground or hot side. in this case its on the hot side. and yes the power for the coil is a switched hot, thats what the relay uses to close the circuit anyways.

 

If they're wired up the same way off of the same signal as per his diagram, I'm just confused as to why you can't use one ignition module for both coils.

 

you could. until it burns up lol. good luck with that. theyre cheap and on all kinds of gm vehicles. easy to find, readily available at every parts store ive been to.

 

Agree with this, and from what I've noticed is that if you get them from auto zone (maybe advance too) then you get a lifetime warranty so if it should go out you're covered for life, unlike a certain j109 option. So with that you may as well move all the ignitors over to the dr100s just so you don't have to worry about whats tacked to the trailing.

As for the voltage difference between straight from the battery and what is in the stock wiring I haven't measured, but it can't be that big a difference. More so I just like the fact that I don't have to splice into my preexisting wiring harness more than I have to, or setup a switch that could mar the interior a bit, and it just so happens that when I turn my key off it drops all the power to the coil AND still out paces any Z06 that has tried to screw with me.

 

I did this mod just as described, and the car runs pretty good. I noticed I was getting a series of slight backfires when taking off through 1st and second gears. I was also experiencing hard cold starts. So I bough a timing light, and saw both leading coils were right on. Then I noticed my trailing were firing at the same time as my leading coils. Then I tried adjusting my trailing timing, but saw no change. Then I disconnected my trailing ignitor, and the trailing coil continued to fire without any effect.

I have the relay wired up. I am using the harness wire that used to supply my leading coil positive side for the Ignition hot for my relay. Then the relay is connected to my leading coils just like in the schematic. Is this causing interference. It appears to me everything else is just as the schematic shows.

I have an 82 carburetored.

 

I just made one more test. If I disconnect power to my leading coil, the trailing timing returns to normal. Then I bypassed the relay, and put battery power to the leading coil. The trailing timing went right back to the same as the leading timing. Then I disconnected the harness ground wire for the leading coil, but that didn't change anything.

 

Double check your wiring. Somethings tying the signal for the L and T colis together.

 

I just pulled the negative wire (ignitor -Tach) off the leading coil and it continued to fire. The plug wire seemed to shock me really easily. I have brand new wires, plugs, cap, and rotor. I separated all my plug wires to make sure they weren't touching. I pulled the Negative wire off my leading coils and they stopped firing right away. Seems real strange.

 

I just checked the resistance of my coi;ls and they came back good.

 

Well I figured out what was going on. I bought the timing light at harbor freight and that might have been my first mistake. I checked the trailing wire after I removed the ignitor wire by pulling the boot off slowly. There was no spark, but the timing light was still blinking on the leading timing. Then i took the pickup off the ignition wires completely, and it continued to blink. Strange that timing light was picking up the leading timing through my battery alone.

Is this something to look in to, or is that just my cheap *** timing light? I am still having the issue of hard cold starts, and the backfiring on acceleration in low gears.

 

Really good info here, thanks to all the contributors. Highly recommend this swap.

 

we just picked up an 86 13b going to put it into a 85 rx7 that was a 12a 6 port
has anyone tried to use the coil packs that came with that engine to make the dlidfis system work very interested in making this work

 

See your other thread, I just replied there. Short answer yes and no. LOL

https://www.rx7club.com/1st-generati...-pack-1136695/