M48 and IEX

[Andrew C]

Looking to run 12 coils off an M48 with an IEX. This is a Porsche 911, with 2 plugs per cylinder. We are using Denso 580 coils. We are thinking that in Wasted Spark mode, we-can split the IEX wire to send signal to both coils on a cylinder? Is this the proper way to feed twin plug applications?

[Holmz]

Looking to run 12 coils off an M48 with an IEX. This is a Porsche 911, with 2 plugs per cylinder. We are using Denso 580 coils. We are thinking that in Wasted Spark mode, we-can split the IEX wire to send signal to both coils on a cylinder? Is this the proper way to feed twin plug applications?

Let's pretend there are 6 plugs.
With 6 wires, one could run 6 coils.
A (with 12 plugs then with 2 plugs per coil... So it looks like a wasted spark but the spark is actually used. And the ECU does not think of it as wasted spark.)

If the firing order has equal spaces then 3 wires can come out and those can go to 3 coils.
The 3 coils run 2 plugs to the cylinders that are 360 apart.
One spark is used and one is wasted - firing on the overlap.

So for a 12 plug you could run each of the 3 outputs and Y those to 3x2 coils, which service the 3x(2+2) plugs in wasted spark, so the sparks are wasted and the ECU knows they are wasted.
Or you could run the 3 outputs into a Y, and then into 2 more Ys and have each of the 3 wires with 4 tails. Those could go into 12xCOP and run in wasted spark mode on the ECU, and they will be wasted on the engine.
Or you could run the 6 outputs into Ys so you have 6x2 tails, and run those into 12 coils or 12 COP. This is not wasted spark from the ECU point of view. Or run the 6 tails into double ended coils that are used for wasted spark like back in A , which is also not wasted.

I am not sure what is proper.
You will need some coil drivers, but whether you use coils (6 double ended or 12 singles) or COP (12), probably depends on a few other factors like reliability, weight, etc.
I cannot see where wasted spark is better if you have the 6 outputs. If you only have 4, then 3 fits within the 4 outputs.
Also one does not need a cam sensor to run wasted spark.

[Andrew C]

Bit confussed.

12 seperate coils, 6 cylinder engine. IEX wit 6 coils signal wires split for each coil signal to fire the two coils for each cylinder.
So I think you mean I can split each cylinders IEX wire to fire each coil per cylinder at the same time.

D580 have their own igniters, so this is a clean setup, just want to be sure on signal v requirements..

Why would this not be waisted? I see in the ECU it is not waisted since it thinks its firing 6 coils not 12.

[Holmz]

...
Why would this not be waisted?
...

It is not waisted, but rather wasted as in:
waste |weɪst|
verb
1 [ with obj. ] use or expend carelessly, extravagantly, or to no purpose: we can't afford to waste



3 wires to your 6 coils produce ignition sparks, and then 360 degrees later a wasted spark. Each of the three wire needs to go to 2 coils.

6 wires to the 6 coils could either have them fire every 360 in wasted spark mode, or every 720 crank degrees in non-wasted mode.

I would not know a good reason why one would choose wasted spark.

[stevieturbo]

I would not know a good reason why one would choose wasted spark.

Not all engines have a cam sensor/trigger fitted for sequential operation

So it isnt a case of choosing wasted spark. That feature is the easier one, you would choose to add sequential though, which may require more work and setup.

Unless rpm/dwell time necessitates full sequential, or you have a knock control system that can accommodate per cylinder retard then there really isnt any benefit as far as sparks are concerned

And of course...not all ecu's will have enough ignition drivers to allow full sequential. So again you'd have to choose a better more expensive ecu to run sequential

So there are many reasons why you would opt for wasted spark, largely cost and time related.

[Andrew C]

We run both ref and sync, and have run this in sequential prior to swapping to the 580 coils, we had Bosch Motorsports 3x2 coil packs and igniters prior, worked well. We are splitting the IEX signal wires and running sequential. 2 coils firing at same time in each cylinder..