Tach reads double the actual RPM
#1
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Tach reads double the actual RPM
OK, I finally found out which wires in the instrument cluster harness needed to be spliced to hook up the tach in my V8 Miata. The problem is that the tach is reading exactly double what it should. I assume this has something to do with how the signal is generated on the V8.
Is there some way to cut the signal in half to make my tach read correctly? I'm using the same signal source on both the Maxigauges and the car's tach. MaxiGauges reads correctly, tach is double those readings at idle and when blipping the throttle.
Is there some way to cut the signal in half to make my tach read correctly? I'm using the same signal source on both the Maxigauges and the car's tach. MaxiGauges reads correctly, tach is double those readings at idle and when blipping the throttle.
#2
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I read about this once... found it:
Don't know if it will work on a miata, but:
Volvo's That Run - Chapter 9 - Speedometer and Tachometer - Turbobricks Forums
Don't know if it will work on a miata, but:
Volvo's That Run - Chapter 9 - Speedometer and Tachometer - Turbobricks Forums
#3
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Ah, looks like there is a potentiometer to adjust, at least on the NA's. Hope it's on the NB cluster.
Help with Tach adjustment - MX-5 Miata Forum
Help with Tach adjustment - MX-5 Miata Forum
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OK, so there is no potentiometer on the NB's. There are screws on the backside labeled sin+ and sin - and cos+ and cos-.
I opened up the tach and this is what I found
When idling at 1000 RPM there is 1000 ohms resistance across sin+ and cos- and there are 800 ohms across cos+ and sin-. Those values do change when the throttle is blipped.
Any suggestions? Any additional readings that I could take that might help the electrical gurus here?
I opened up the tach and this is what I found
When idling at 1000 RPM there is 1000 ohms resistance across sin+ and cos- and there are 800 ohms across cos+ and sin-. Those values do change when the throttle is blipped.
Any suggestions? Any additional readings that I could take that might help the electrical gurus here?
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replace the factory tach with an aftermarket tach in the cluster. I messed with my tach for a few weeks before I said screw it and made one fit and works better than I could have imagined.
#12
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I did send an email to Hakan to see if there was any way to pull an output from the MaxiGauges. It obviously has a similar converter built in as those gauges were reading double actual RPM when I installed them but in the setup menu I was able to switch from 4 to 8 cylinders (or vice versa) and it started reading correctly on the digital display.
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I bought a Dakota Digital box the other day. For $80 I can forget about it. Still need to get a speedo healer and tie into the VSS but speedo can wait. That's all that is left.
Going for sand and buff next Saturday. It's never been buffed since paint.
Going for sand and buff next Saturday. It's never been buffed since paint.
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