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Old 01-17-2011, 11:22 AM   #1
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Default Connecting 92 tach to DIYPNP

I have a 92Miata running a DIYPNP and VVT controller to run a2001 engine. I connected the 01 coils through the 15 pin connector. now my tach doesn't work and I understand why but can I use the tach out in DIYPNP through the 15 pin connector to the yellow/blue tach wire and bring my tach back to life?
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Old 01-17-2011, 11:37 AM   #2
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yes
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Old 01-19-2011, 10:59 AM   #3
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eh,..no.

I wired the tach from the DIYPNP TACH to a pin on the 15 pin connector then out to the 92 Miata tach wire (yellow.bluestripe) Turned it on and still no tach.

I'm using the 2001 coils on this car.

Here's the settings I used on the tach output.

What am I missing?

thanks
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Connecting 92 tach to DIYPNP-tachout-screen.jpg  
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Old 01-19-2011, 11:31 AM   #4
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You need to grab a 1k 1/4watt resistor, open your diagnostics box and jump IG- with B+ with the resistor. Or you could do the same within the MS box by jumping that Tach input wire with a 1K resistor to 12v inside the unit itself.

It needs a pull up on the signal and there is none currently.
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Old 01-19-2011, 11:53 AM   #5
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The pull up is already in the DIYPNP.
I'd suspect something more along the lines of a wiring problem.
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Old 01-19-2011, 11:57 AM   #6
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then are we certain "the pin" you picked on the db15 is the same that is going back to the TACH hole on the mainboard?
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Old 01-19-2011, 12:01 PM   #7
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That was my thought as well. I would suggest checking for continuity back to "TACH" on the DIYPNP main board.
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Old 01-19-2011, 01:50 PM   #8
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I'll check for continuity. Thanks
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Old 01-20-2011, 11:36 AM   #9
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I checked continuity and found a wiring issue in my fat fingered soldering on the 15 pin connector. I fixed it by moving both wires to the next pin on the DB15 and had continuity, turned on the Tach output, fired the car and still no tach.

Can the pullup fail? Can the tach fail? Worked fine with the MSPnP

Or are there other settings that I'm overlooking?
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Old 01-20-2011, 12:21 PM   #10
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I could never get the tach to work on my 93 with the diypnp. I went back to the 1k resistor in the diagnostics box. When I enabled tacho after wiring into the blue yellow wire; the tach signal worked fine at idle, but didn't move correctly with engine rpm. Maybe I wired something incorrectly in the diypnp
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Old 01-20-2011, 12:59 PM   #11
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Where are you tapping into the yellow/blue wire?
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Old 01-20-2011, 01:17 PM   #12
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I tapped the Yellow/Blue wire where it comes into the Diagnostic connector on the drivers side of the engine bay.
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Old 01-20-2011, 01:33 PM   #13
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yeah that should work. is the ignitor still plugged in?
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Old 01-20-2011, 01:48 PM   #14
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The ignitor is still plugged in.
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Old 01-20-2011, 02:28 PM   #15
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unplug it and see what happens.
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Old 01-20-2011, 02:54 PM   #16
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Quote:
Originally Posted by JohnW8 View Post
The ignitor is still plugged in.
Oh? Yes, you 100% need to unplug it. It has a tach output on it.
I'm not sure if that has any negative implications as far as potential damage to the DIYPNP tach driver (which is on the module).
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Old 01-20-2011, 03:26 PM   #17
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I clipped the wire under the dash on mine,a nd then connected the tach out wire to it.

Should I have also cut the tach feed wire coming out of the ignitor?

OR does that mean that when you install cops with a diypnp you do not need to run the tach signal wire to the COPs?
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Old 01-20-2011, 03:40 PM   #18
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Well the Coils are what send the signal to the dash tach. so if you have both the coils AND diypnp sending out a signal, that could be an issue.
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Old 01-20-2011, 03:55 PM   #19
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Quote:
Originally Posted by Braineack View Post
unplug it and see what happens.

I had a gutted igniter in place to keep a factory appearance and my fuel pump would cycle in short bursts. I didn't try starting it at that point. When I swapped in the working igniter the fuel pump quit cycling. It would do the normal startup fuel pump routine...
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Old 01-20-2011, 04:03 PM   #20
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Quote:
Originally Posted by Braineack View Post
Well the Coils are what send the signal to the dash tach. so if you have both the coils AND diypnp sending out a signal, that could be an issue.
But I removed the 92 coils and replaced them with the 01 coils that don't utilize the 92 ignitor. Does the ignitor itself generate a signal?
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