Terry,

I'm not sure how you specifically build 420A input circuits, but generally speaking, the modifications required create the exact same circuit on both the v3.0 and v2.2 boards. How exactly did you build your input circuit?

I respect your opinion, Terry, but here's why I do not think the issue is within the board:

When we bench test our v3.0 units, there are absolutely no peculiarities in the crank signal. Up and down the entire RPM range, we measure consistent signals with no spikes.

At standard engine speeds, the crank signal is not oscillating fast enough to be generating any significant RF artifacts. Furthermore, given the internal ground and power planes, the tach input circuit is isolated from noise rather well.

In car, we still do not observe any irregularities in the signal.

Using the process of elimination, the only difference between our units and yours is the wiring harness. We use coaxial cable with a grounded sheath... For this reason, I do not think a twisted pair would mask the problem so much as solve it.

As you suggested, perhaps the sensor itself as fault... that would be odd considering it works fine with the v2.2 board, though.

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-Paul

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