graph rpm spikes

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graph rpm spikes

Postby aussiedragster » Thu Nov 02, 2017 6:26 am

often around the shift and sometimes after the finish line i'm getting a crazy zig zag on the graph spiking up and down 5-600rpm within a 100th/sec or so lasting for a period of a tenth or two.surely this is electrical? no way rpm can vary so much in this time frame.engine sounds clean so could it be a sign of a bad coil or rpm wire is wrapped around spark plug lead,i know it's supposed to be on wire to kill switch but seems to work fine on plug lead on another car.funny always appears same spot around the shift never mid run or before finish line.thanks
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Re: graph rpm spikes

Postby Pool Man » Sun Nov 05, 2017 10:23 am

Do you have a graph
I deserve respect for the things that i DO NOT do.
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Re: graph rpm spikes

Postby Farock72 » Sun Nov 05, 2017 10:53 am

Hook to kill switch and try it.
If its a mychron instructions say hook to hot side of kill switch.
worked for me had same issue
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Re: graph rpm spikes

Postby slowgoat » Sun Nov 05, 2017 3:56 pm

This is a sign problem, wrap your rpm wire around the spark plug wire and the issue will be fixed
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Re: graph rpm spikes

Postby aussiedragster » Mon Nov 06, 2017 4:17 am

thanks for the replies,would like to post a graph but still working out how to do that,but wrapped the pickup wire around the wire from coil to kill switch and done a few passes and it seems to have gone.will download soon and have a closer look but graph on mychron itself doesn't seem to show them anymore and rpm and jackshaft line as a whole seems a lot cleaner.funny how it works ok on one car and not another,is it possible that it appears [electrical interference] at the shift as rpm is peaking?
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