better spark circuit swap IGN and IAC2B

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08-10-2010, 06:03 PM

heychris

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better spark circuit swap IGN and IAC2B

Another question.. Thanks for your patience and help...

on the miata turbo wiki
http://miataturbo.wikidot.com/MS2_a

They swap the IGN and IAC2B from Joe's circuit

https://www.miataturbo.net/megasquirt-18/better-spark-out-circuit-33964/

Why is it swapped?

08-10-2010, 06:18 PM

Ben

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The way an MS1 is normally set up fires Miata coils in the opposite order compared to how an MS2 or MS3 is set up.

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08-10-2010, 06:40 PM

Braineack

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dont question, just accept.

08-10-2010, 06:49 PM

Joe Perez

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Pretty much what Ben said.

The "classic" DIYAutoTune wiring of the ignition system puts "Spark A" on the 2/3 cylinders, and "Spark B" on the 1/4 cylinders. Depending on your point of view, that could be considered backwards. However, they also set up the decoding of the CAS "backwards", so it all evens out in the end.

I personally wired my ignition the "correct" way, as I'm running a 36-1 crankwheel with the missing tooth in the traditional location (just prior to TDC), therefore my firing order cannot be reversed in software to compensate for reversed wiring.