Is there a way to check tach filter? Tach jumps all over when starting and pegs under accelaration? Or is it bad tach?

quote Originally posted by Wayne Renninger: Is there a way to check tach filter? Tach jumps all over when starting and pegs under accelaration? Or is it bad tach?

I think the only other way is to bypass it... and see if it stops "floating," though it could be inaccurate.

Definitely sounds like a bad tach filter, not the tach though. Could also be a bad ground...

Take it out of the circuit and replace it with a bare wire. The tach should work but better than it has been,
The filter effectively blocks high-frequency ignition noise so only clean ignition pulses are sent to the tach. If you have an extra just replace it and see,

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