Graphing RPM

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Autonerdz
TwoWaves
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Re: Graphing RPM

Post by Autonerdz »

Here is a case where an RPM math channel was applied to a one degree optical CMP a few years ago.

http://www.autonerdz.com/cgi/yabb2/YaBB ... 08802930/7

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This technique, of course, works best with higher resolution signals.

In this case, it was very helpful to easily see if signal degradation was the cause or the effect of a stalling situation as it illustrated where the RPM fell.

Jasonr23
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Re: Graphing RPM

Post by Jasonr23 »

Hi

With further questions for graphing RPM. I have an earlier Ford with a hall effect internal to the distributor. From the wiring diagram i attached can i use any of the wiring you see to gain an rpm signal? or can i gain an rpm signal from the coil lead?

TIA

Jason
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Jasonr23
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Re: Graphing RPM

Post by Jasonr23 »

Taken from a ford tfi-4 ignition module it's the crank signal wire. Any guidance for turning this into rpm using the math function? Seems the reluctor has total 5 + 1 teeth?
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Steve Smith
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Re: Graphing RPM

Post by Steve Smith »

Hello and thank you for the post

There a number of options to try depending on the number of pulses per one revolution of the crankshaft

Assuming your speed/crank signal is connected to channel A you could try 60/5*freq(A) for 5 pulses per crankshaft revolution

Alternatively you could use Crank(A,5)

These should tally with your tachometer but if not you could amend the number 5 to a value that corrects the rpm value

The following links should help here and here

I hope this helps, tale care......Steve

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