MX5 / Miata - Pulses Per Mile

MX5 / Miata - Pulses Per Mile

Postby Law » Thu Aug 18, 2016 4:40 pm

Good Evening,

Thank you to Jean for replying to my email regarding the Duel VR info.

I may even answer my own question here. But I thought I would ask.

I'm in the process of installing a Race Tech Dash2. Which requires a Square voltage signal.

The VR device by jbperf will do this perfectly for me.

Now the thing I'm trying to get my head around is working our the pulses per mile. I think without double checking I have a live monitor I can use on the laptop with the Dash2 to view all the sensors RAW information before the Dash2 converts it to X value.

So the sum is Miles/Circumference * 1 wheel rotation pulses = Pulses to enter into Dash2 per mile

1609/1.841 * ?

As the sensor is off the rear of the gearbox. I'm guessing the sensor should still work if I spin the back wheels by hand. (Could be wrong)

So could I turn the wheels 1 full turn and record how many pulses it gives either by a voltage reader (may miss it) or the software.

Not sure if this is ideal at all.

But wondering if anyone has any experience or advise or a suggestion for a better idea.

The OEM mk2 NB dash cluster converts the signal to 4000 pulses per mile and that what it expects. So adjusting the Gear on the sensor to match the rear diff ratio will always give you 4000ppm. The 4000 is what I've pulled from miataturbo forums. Not sure how correct this is.

Thanks. :D
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Joined: Thu Aug 18, 2016 1:29 pm

Re: MX5 / Miata - Pulses Per Mile

Postby Rod S » Fri Aug 19, 2016 4:43 am


Re. the turning wheels to work it out, that's fine, I've done it myself.

Just bear two things in mind, first you want the rolling circumference of the tyre for your calaculations, not plain 2*Pi*r because they aren't round when in use. The difference is minimal but most tyre manufacturers do quote the rolling circumference (or rolling radius). Secondly, if you jack up one side and leave the other wheel stationary on the ground and just turn the one, the propshaft/final drive rotates at half the speed it would normally because of the differential.

Hope that helps,

Rod S
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Joined: Mon Sep 06, 2010 4:03 am
Location: Rural Suffolk, England, UK

Re: MX5 / Miata - Pulses Per Mile

Postby Law » Mon Aug 22, 2016 4:37 am

Thank you for the advise.

I will bear that in mind when doing it. It's good to know I can do that trick to work out the pulses per one full wheel turn.

I will update with how I get on. :D
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Joined: Thu Aug 18, 2016 1:29 pm

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