Cutting out at ~ 5k RPM

Ben Swann benswann at
Sun Sep 16 17:58:49 PDT 2007

I have been tuning the Megasquirt Fuel combined with MAC-14 ignition and
accelerates like banshee to about 4500 RPM then I get breakup like points
flutter or incorrect dwell as relating to older point style ignition.  I think
I have some sort of ignition problem because engine breaks up at around 5k
regardless of fuel parameters – I have played with enrichment and enleanment
within safety limits and fueling does not seem to make much difference.

I suspect a coil breakdown, but wondering if anyone else has seen this.  This
balanced engine should rev out beyond 7K with this setup as rev. limit is way
up there(not set any limit yet).  I checked wires and does not correlate to
any single wire.

There is plenty of fuel and pump pressure to make it get plenty rich, which
makes me believe even more that I have an ignition problem.  Can’t believe it
would be + feed wire to coil which is at least 10 guage or greater to battery.
Would there be any need to install a cap – this is not on the 200 (10 or 20V)?

Engine falls flat even if not under load at around 5000 RPM – sometimes as
early as 4500 – usually when under load or approaching 2 bar, or at no load
condition might actually get to 5400 RPM then breaks up.  I will try swapping
coil, but seeing if anyone else has experienced this sort of cut – I have seen
similar cut over 6800 RPM on 20V or over 2.5 bar, but this is ridiculously


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