1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

79 rx7 tach bouncing?

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Old 08-28-14, 08:04 PM
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79 rx7 tach bouncing?

Hi all. Would be quite grateful for some assistance. Stu--you still around? Bone stock 79 Rx7 12a points ignition. Runs great but tach has just mysteriously started bouncing erratically from 2 grand to 7 etc back and forth while the car sits at idle. car has been in storage for awhile if that matters. Pulled the battery and alternator and had them checked today. Replaced points, cap, rotor, plugs, and coils...checked all connections for coils, dizzy, battery, and plug wires. Replacing plug wires tomorrow. What else could it be? It seems like it would be simple so I have done the simple things that are the usual suspects--especially the trailing coil. Any ideas? Oh--and now that I replaced the points, any tips on how to set them? Going to hop on faxed.ca and check out the manual. All other ideas are greatly appreciated. Thanks!
Old 08-28-14, 10:14 PM
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OH bouncing

I personally would check the grounds. They have been known to do very random and weird issues when the grounds corrode from age.
Old 08-29-14, 12:04 AM
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It might be the voltmeter activating.
Old 08-29-14, 01:04 AM
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Originally Posted by Jeff20B
It might be the voltmeter activating.
Which would mean check relay is messing up, if I recall correctly.
Old 08-29-14, 10:56 PM
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its either the choke and check relay, or the points. if the ignition misfires, it'll register on the tach, and it will misfire if the points are bad
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