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Old 09-19-2011, 08:42 PM   #1
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Default tachometer discrepancy?

diypnp
90 1.6
stock everything else

i noticed that when i hit the rev limiter the laptop said i was bouncing around 7k and my tach said around 6k

so i decided to log it and perform a 7k shift

in the log the the rev limit bouncing was showing 7k (my tach 6k)
and when i performed the 7k shift the log showed 7k as well as my tach showed 7k

is the oem tach slow reacting?
i just dont get it cuz with my oem ecu my oem tach showed bouncing around 7k when i bounced off the rev limiter

whats going on here?
i just dont get it

thanks
jared
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Old 09-20-2011, 09:12 AM   #2
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Often it's only after installing a standalone that gives you a digital reading from the sensors directly that you find out just how inaccurate your stock tach is. The stock tach is still being driven off the factory ignition module and the readings it gets are not affected by what ECU is in charge.
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Old 09-20-2011, 01:21 PM   #3
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Stock tachs suck. I can bury mine to 8k and im really not even at 7 yet.
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Old 09-22-2011, 06:09 PM   #4
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i have never messed with revlimiters before so i had set the diypnp for fuel and spark cut, i figured why not
i googled how the miata ones work
they only use fuel cut
so i changed it to that

and now the discrepancy has vanished

the tach was hitting aprox 7400 and the data log showed a max of 7384
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