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aftermarket tach

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ERusinko:
I've tried 2 different tachs and when i hook them up they both peg at 10,000 while the car is at an idle !
I'm conected to a switched power (Red), tried 2 different grounds (Black), and hooked to the negative side of the coil (Green).
Is there something different with electronic ignition ?
1978 Pinto 2.3 litre
I could appreciate any help !!
Eddie Rusinko
Yuma, AZ

Wittsend:
Is it possible someone reversed the factory wires at the coil? I'd remove both wires and test for voltage at each with the ignition on. I'd assume that the electronic ignition still triggers the coil by switching the ground on and off like a points distributor. Otherwise from your description it sounds like it is wired right.

PintoTim2:
Any chance the ignition module is doing multispark?   

davidpinto:
AFTER MARKET TACHS HAVE A SWITCH FOR 4,6 OR 8 CYL.SOME ARE ON THE INSIDE OF IT,WOULD NOT READ RIGHT IF NOT SET  FOR 4 CYL.

Wittsend:

--- Quote from: davidpinto on May 01, 2023, 06:51:07 PM ---AFTER MARKET TACHS HAVE A SWITCH FOR 4,6 OR 8 CYL.SOME ARE ON THE INSIDE OF IT,WOULD NOT READ RIGHT IF NOT SET  FOR 4 CYL.

--- End quote ---

That is a good point that I forgot to consider. However, I believe if it was set to 8 (or 6) cylinders that it would read lower, not higher. And even if it is the other way around it would only double and a 900-ish RPM idle would be 1,800 RPM, but he is pegging at 10,000 RPM. So, while he may not have it set in the right position (and should make that correction as you note) the 10,000 RPM idle likely has another cause.

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