My Tach reads incorrectly. At idle, the tach reads 4500 rpm. Press the gas pedal a little and the tach pins itself in the zed zone. Any ideas what would cause this?





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Edwin
1986 IROC, 1992 Body Kit, 1989 5.7 IROC Engine, Crane Cam, 3" CVX Exhaust, ADS Superchip, 24# FoMoCo Injectors, Gutted Cat, AFPR (45 psi), Airfoil, 3.42 Gears, MAF Screens removed, Gutted Airbox, K&N Filters

 

Hmmmmm, could be several things. The tach itself might've gone bad, the needle moved on the shaft so that it's no longer at zero, or the needle is merely stuck. The first thing I would try is remove the instument panel cover and see if you can free up the needle. My tach got stuck once, and that's how I fixed it. If your tach is functioning properly, the needle should go to zero RPM when you turn the key on before actually starting the engine. If it doesn't go to zero when you turn the key on, chances are the needle's probably just hung up.

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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."

 

The needle goes to 0 when the car is off. It doesn't look like the needle is twisted around the shaft because the tach completely over-reacts to throttle input. One blip of the throttle from Idle sends the needle from 4000 (the reading I get at idle) to deep in the red zone. I think I need a new tach.



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Edwin
1986 IROC, 1992 Body Kit, 1989 5.7 IROC Engine, Crane Cam, 3" CVX Exhaust, ADS Superchip, 24# FoMoCo Injectors, Gutted Cat, AFPR (45 psi), Airfoil, 3.42 Gears, MAF Screens removed, Gutted Airbox, K&N Filters

 

I also need an answer to this problem. According to my tach, the 305 in my Camaro RS flys up and over "7 grand" with ease.

 

Same with mine at idle its at 2k rpm hopefully you find a way to fix it and tell us how you did it

 

this really belongs in the electonics board, but heres a thread to fix 90-92 tachs, found it with a quick

https://www.thirdgen.org/forums/elec...meter-fix.html