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Four pin COP to standalone CDI

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I am trying to figure out how to drive the Porsche Cayenne four pin coils by a standalone CDI (M&W)

Now I am stuck and have a couple of questions, hopefully you can shed some light, thanks a lot:

1. Is it correct that two pins are for the OEM ECU to monitor if the coils fire?

2. Can I leave this checking circuit connected and the OEM will not detect that it is not controlling the coils anymore?

3. Do you have suggestions as how to wire it? Pin A1 and A4 seem to be the checking circuit ? (partial factory diagram attached)

Attached Files

Heres a section out of the M&W instructions that may help


COP (coil on plug) coils with inbuilt drivers are not suitable for use

with CDI ignition. COP coils designed for inductive ignition may

contain a blocking diode in the secondary winding which must be

considered during wiring (see coil polarity note below). Use resistive

spark plugs with all COP coils. Keep plug gap < 0.025” (0.6mm) to

prevent coil damage. DO NOT use AEM pencil coils under any


Thanks for the pointer.

How about alternatively, respectively for the sake of understanding the four wire coils, if we'd run them from a Aftermarket ECU (sample Haltech Elite 2500) and drive the coils like that. How would one wire them?

You only need to use 3 of the wires if you are to run them as inductive COP's, +12v, GND and the signal wire.

From the look of the diagram you've posted I think it wires as follows(someone correct me if I'm wrong):

A1 - GND

A2 - possibly the fire signal

A3 - +12V

A4 - possible the tacho signal (confirmation of fire) Might require earthed

I stand corrected

A1: Ground (ECU ground ?)

A2: Ground to the secondary (engine ground ?)

A3: +12v to the primary

A4: ECU (to the internal transistor)

That's the internal transistor that make the primary coil discharge to the secondary.

No checking circuit or tacho signal on that coil.

I believe they are:

Pin 1 - Engine earth

Pin 2 - ECU earth

Pin 3 - 12v

Pin 4 - ECU Trigger

CDI ignition isn't compatible with an internal igniter coil which is what these appear to be. You'd need to swap to a coil that's designed to use an external igniter module.

Internal igniter coils can be driven directly from an aftermarket ECU.

Thank you all for sharing !

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