Hey guys, I just tuned up my car today(Plugs, cap, rotor, wires, 02 sensor) the car was running good before the tune up, but my Tachometer had like a jump to it (it would click up about 300 RPM's and down again) (almost like a second hand on a watch) it just kept doing it up, down, up, down, etc. Not your usual bounce like when a car is missing or running rough. I changed the cap & rotor and plugs , wires, and it does not do it anymore. The tach does not move at all it unless of course I rev it. I think it was a defect that was on the old cap, or rotor. I know the tach works off of the distributor, so this seems to make sense to me. I know that a while back, there were a few guys in here, that had problems with jumping tachs, and I thought this might help some of you. Cap & rotors aren't that expensive, so it is an easy thing to try if you have a prob with the tach. I hope this helps some of you out there. It is nice to look down at the tach and not have it bouncing up & down.
Take care guys
Mike

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(Gran Turismo Americano) "The Ultimate Firebird"
Smokin 1989 GTA- Bone stock except for exhaust. (no catalytic-stainless pipe into Flowmaster 2 chamber).