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Author: Subject: Tacho frequency
pekwah1

posted on 14/12/16 at 08:52 PM Reply With Quote
Tacho frequency

Hi Guys,

I've got a dash unit that can handle either 166hz or 333hz signal.
Now i know nothing about tacho's and such, but will this work with a 2.0 blacktop zetec?
If not, is there a way to make it work?

Thanks in advance.
Andy

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r1_pete

posted on 14/12/16 at 09:57 PM Reply With Quote
Have a look here, open the instructions and then the audio file calibration link, it may give you some pointers.

https://www.spiyda.com/magento/index.php/smiths-rvi-rvc-conversion-board.html

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obfripper

posted on 14/12/16 at 10:14 PM Reply With Quote
You should be ok for 9999rpm max with the 333hz input setting and a tacho feed giving 1 pulse per ignition event/2 per revolution.
Depending upon your ecu you'll either have a dedicated output, or will need to create a diode arragement like below from the coilpack to feed the tacho input.



Dave

ETA
http://www.useasydocs.com/details/EDIS_tach.gif
The embedded pic works on my phone, but not on pc for some reason.

[Edited on 15/12/16 by obfripper]

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pekwah1

posted on 14/12/16 at 10:16 PM Reply With Quote
Thanks for the link, i've had a quick look and not much the wiser tbh.... Obviously that's geared towards a calibration tool though
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pekwah1

posted on 14/12/16 at 10:18 PM Reply With Quote
Thanks,

The reason for asking is that i've just taken a CVH out of the car to replace with a blacktop, and the tacho didn't seem to work at all running off a coil... didn't know whether the zetec would be different

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obfripper

posted on 14/12/16 at 10:45 PM Reply With Quote
What dash unit is it?
Any link to specs etc may explain more, there may be more setup involved on the dash unit.
Most modern stuff will usually work with a plain 12v pulse signal, older analog tachos need the spike from a coil to give a response and will not respond to a clean 12v pulse.
If you're using megasquirt with edis, pin 11 on the edis unit is a clean tach out.
The donor car ecu will have a clean tach out on pin 48 if you're going that route.

Dave

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snapper

posted on 15/12/16 at 05:50 AM Reply With Quote
Megajolt diode pack for direct signal from coil pack
autosportslabs website show how to build and wire to the coil pack





I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)

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pekwah1

posted on 24/4/17 at 11:20 AM Reply With Quote
Digging up an old thread here.....

Thanks for the info so far, i found the picture that obfripper posted as below:



And as he states, i appear to have pin 48 from the ECU that sends the tacho signal.
The tacho i have only has two settings of either 133hz or 333hz, that's it, nothing else i can change.

I guess i just need to hook it up and try really and see what happens, at the moment i've tried taking off pin1 on the coil which didn't work, so will try the one from ECU, and failing this maybe go with the diode approach.

Regards,
Andy

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