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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)
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 !