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post #2 of (permalink) Old 9th December 2006
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I'm guessing that the rev counter module is designed to work on a conventional single coil and distributor engine. It'll be expecting twice as many pulses as any one of your coils is generating, and so I imagine you'll get half the reading. Even with four separate coils , the engine will still operate on the 'wasted spark' system. A crank position sensor (or TDC in Renault terms) can only tell where the crankshaft is. The 'suck, squeeze, bang, blow' cycle is dictated by the camshaft(s) which turn(s) at half the speed, so the ECU actually fires twice for each cycle, once where you'd expect it, and again (pointlessly) near the end of the exhaust stroke.

This may not work, but it has to be worth a try. Get a couple of silicon diodes from your local electronics supply shop. Connect the ends with the band markings together and connect this to the input for the rev counter. Connect the other ends of the diodes to the negative sides of two different coils . You may have to experiment as to which coils to connect up to. It's pot luck as to whether you'll get two that fire together or not.

What this should do is allow the pulse through to the rev counter from each coil , while preventing it from feeding back to the other coil via the diodes. I reckon it should work, though the standard disclaimer (you follow this advice at your own risk) applies.
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