sonicgroove

iTrader: (2)

https://www.rx7club.com/3rd-generati...-rail-1119103/

Reading through this thread I came across people mentioning a mod that essentially does the same thing as the fuel pump rewire mod except with the coils/igniter. This mod was noted to have been done by Chuck and Chris. Having just done the fuel pump rewire and confident my car will produce sufficient amounts of fuel in the upper RPMs, solid and consistent spark is the left over concern. Splicing a direct 12v line from the battery to the coils/igniter seems like a great way to assure consistent and reliable spark unless of course they were engineered to see lower voltages than the battery supplies and changing anything would otherwise result in failure of the device(s) to function?

https://www.rx7club.com/3rd-generati...iagram-964089/

Upon research I came across this thread. If my understanding is correct on how this mod is done a 4 pin bosch relay will be needed, along with some wiring accessories/tools, utilizing the black/white coil/igniter wire. So would the procedure go as follows?

Pin 86: The black/white wire will be the switch trigger since it is 12v IGN source, so black/white wire originating from IGN goes to pin 86
Pin 85: Chassis/battery ground
Pin 30: Direct Battery 12v (+) connection, preferably with an inline fuse (how many amps?)
Pin 87: black/white wire going to the coils/igniter

Can anyone confirm is this is correct? If not at least confirm I'm not revealing any hidden secrets or passing on bad information? Thanks

-groovin

jaaf

iTrader: (3)

interesting!

scotty305

iTrader: (2)

Yes, that should work by connecting things as you've described. Rewiring the fuel pump so it doesn't draw power from the ignition switch will help leave more power available to the coils. The factory harness sends the coil power through a 40A fuse, then through the ignition switch, then to the coils, so try to get a relay with max current rating of 40 amps or greater. The power from the ignition switch is also shared with the fuel pump, so the coils wouldn't need a 40A fuse all by themselves. You can probably get away with a 20A or 30A fuse for the new length of wire you add between the battery and the relay. Ideally that fuse should be located a short distance from the battery.

DaleClark

iTrader: (55)

I looked into the wiring diagram when this was brought up in the fuel pump rewire thread. I agree that you will need an aftermarket relay, unlike the fuel pump mod there isn't a relay for supplying power to the coils.

But, I would also test this as well. Put a meter on and find out what voltage to the coils is like under different conditions - idle. full load, with an electrical load on. Then test afterwards.

When I did my original fuel pump rewire I tested before and after and found a significant difference, like 1-2 volts.

This is something on the LONG to-do list for me once I actually get to work on MY car again .

Dale

mikejokich

iTrader: (1)

I was one of the people who mentioned the mod in the other post. Chris did this to my car a few years ago and there is indeed a relay that sits just below my cruise control bolted to the side of the strut tower. I will be working on my car this afternoon and I will confirm the correct wiring. I will post this later.

mikejokich

iTrader: (1)

I checked my ignition rewire and what groovin posted appears correct. The only thing I was not able to do is the confirm the B/W wire was cut since the wires were tightly taped and I didn't want to accidentally cut through the wires to get the tape off. I would check which wire to cut since the only one with switched 12V power is the right one. Also, you should make sure to cut the wire on the engine/ignitor side of the gray connector so as to still be able to plug in a HKS Twin power in between the gray connectors and the coils. The constant power wire from the battery came from the main fuse box with a ring connector on the feed from the alternator/battery. Chris used 12 gauge wire with the constant power from the battery on 30. 86 would indeed come from the switched 12V, the wire coming from the engine/ignitor, again likely the B/W. 87 would then go to the wire going to the gray connector and then either through the Twin Power, if you have one, or directly to the coils. 85 to ground, the bolt used to bolt down the relay to the strut tower.
Mike

sonicgroove

iTrader: (2)

Thanks for the confirmation. I have a few things I need to complete but when I get a chance I'll try to do a write up on this. I'm thinking that last open fuse slot might be the new home for powering this mod.

-groovin