5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Tach 2x rpm

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Old 07-18-2007, 03:47 AM
  #1  
FoxGT
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Default Tach 2x rpm

Not sure why or how to fix this, but the tach on an '88 GT is reading twice as many rpm as it should be. at 2k rpm it reads 4k rpm. Any way to fix this?
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Old 07-18-2007, 04:59 AM
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raven_ghostwolf
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Default RE: Tach 2x rpm

was the tach replaced recently from a doner car? if the car was a 4 cyl. then there should be a switch on the back of the tach that indicates either 4 cyl or 8 cyl. I know the older 4 eye tachs had this never really looked at the 87 up.
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Old 07-18-2007, 05:16 AM
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FoxGT
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Default RE: Tach 2x rpm

Not sure, just got the car. I'll look when I get a chance to work with it.
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Old 07-18-2007, 06:17 AM
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daleclough
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Default RE: Tach 2x rpm

There's a switch on the rear of the tach. As raven_ghostwolf said, it's was probably from a 4-cyl.

Easy removal/fix.

Cheers!
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Old 07-18-2007, 11:36 AM
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67mustang302
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Default RE: Tach 2x rpm

Yep, it's setup for the ppr on a 4cyl, switch it to the V8
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Old 07-18-2007, 12:21 PM
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FoxGT
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Default RE: Tach 2x rpm

thank you guys
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Old 07-18-2007, 03:35 PM
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NorCal5.0
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Default RE: Tach 2x rpm

did it work cuz i have the same problem? im gonna look at it right now tell you what i see...
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Old 07-31-2007, 12:56 PM
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Default RE: Tach 2x rpm

ya i got the same problem......., twice the rpm it really is. I also went from a 140mph to a 85mph speedo and now it reads wrong. I figured it wouldnt make a difference. The whole cluster is out of a 91, 4 cyl.
I like the 4cyl gauges better it keeps me out of trouble. LOL
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Old 07-31-2007, 09:28 PM
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lookin4astang
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Default RE: Tach 2x rpm

Yes it does matter. If you change the speedo, you will have to change the speedo gear to correct the mph. Also, as numerous guys have stated already, the tachs in these things were the same whether it be a 4,6, or 8 cylinder. There was a switch in the back and that's all it takes to fix it.
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