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Stock in dash tach not reading correctly

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Old 06-21-2011, 02:23 PM
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Default Stock in dash tach not reading correctly
I got my 69 Camaro running with the LS-2 and am trying to use the factory in dash Tach, but it seems that the ECM must give off a different pulse, because the RPM's seem way low. Has anyone else ran into this and is there a cure to run the factory tach?
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Old 06-21-2011, 02:25 PM
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Most likely the factory pcm is still set for a 4 cylinder signal. Are the readings about half of what they should be?

Originally Posted by kwkrat2
I got my 69 Camaro running with the LS-2 and am trying to use the factory in dash Tach, but it seems that the ECM must give off a different pulse, because the RPM's seem way low. Has anyone else ran into this and is there a cure to run the factory tach?
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Old 06-21-2011, 02:27 PM
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1/2 would probably be accurate. Wouldn't the PCM be set for the GTO tach?
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Old 06-21-2011, 02:41 PM
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Originally Posted by kwkrat2
1/2 would probably be accurate. Wouldn't the PCM be set for the GTO tach?
Don't ask me why GM decided to have the pcm's send out a 4 cylinder tach signal, but they did.
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Old 06-21-2011, 03:07 PM
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So is this a re-program issue?
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Old 06-21-2011, 09:55 PM
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Just have the person that did the programming to set the tach output to 8 cylinder.
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