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Direct Fire Ignition FD3s, What Should I Use For 4th Ignition Signal?


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I'm really hoping this is the correct place to ask this question, and I apologise if it isn't!

I have an Rx7 S7-8 pnp G4+ Ecu that I'm using on my Bridgeport 13b.
I'm ditching the stock ignition set-up in favour of the LS1 coil packs that are known to handle ignition demands much better in higher power situations. I'm hoping to figure out a way to run the leading plugs in direct fire, the same way the trailing plugs are. As the coil packs will struggle at higher RPM in the original wasted spark set up. 

I've found the factory three ignition outputs from the ECU for Leading 1 and 2, Trailing 1, and Trailing 2 and I've de-pinned them from the Ignitor plug ready to wire into the LS1 Coils. I'm now at a loss as to what to use for Ignition 4 as according to the manual that has been appointed to the Aircon-clutch (Which I intend to keep in the car). Is there another output I can set that to? Or will I need to purchase an expansion loom to gain Igntion 5,6,7 and 8. (I'd rather not purchase an expansion connector if avoidable, just to be able to run one more Ignition output for direct fire). I've used the help system to determine how to change the ignition mode to "Rotary - Leading Direct". 

I'm sure there is a very simple answer I'm missing and I apologise for that in advance! 


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You will need to repurpose the Ignition 4 for the direct fire for the extra leading coil.

You then have 2 options I think:

1) Use an Expansion connector loom to change Ignition 5 to Air Con.

2) I have also seen people who disable the Fuel Speed feature and run their pump at full speed all the time repurpose the Injection 5 output to AC/Clutch

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  • 1 year later...

Can you explain a little more in depth. I am about to do the same thing. I going to buy the plug in ecu for my 93 rx7. I can under stand changing the setting for ignition 4 but can someone explain with a wire diagram. What wires are need to be used?

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Note the above posts were relating to the S7/8 ECU so your S6 will be slightly different.

You need the "ignition 4" output to drive the 4th coil for direct spark - however ign 4 in the stock configuration was used to drive the AC clutch.  So you need to move the AC clutch wire off the ign 4 (pin 87), If you still have AC then I would suggest you move it to Inj 7 (pin 52) (which was originally the "Cat light" so not too important).  Leave the cat light wire disconnected - tape up out of the way.  Now you have ign 4 free to drive your coil. 


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