Weird Idea

General Megajolt Questions and Answers

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Luca Lagonigro
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Joined: Sun Feb 29, 2004 9:23 pm

Weird Idea

Post by Luca Lagonigro »


What is the lower RPM limit for the MJLJ and EDIS module?

I'm asking this question because I just had a weird idea: create a 36-1 sine wave with a PC sound editor and burn a audio CD with this signal...

Then play the CD on a 12V player and connect 1 speaker output - + to -VRS and +VRS input on the EDIS module.

Impedance on the module should be high enough to be handled by the CDP powerpack.

What do you think?

brentp
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that could work, but it would

Post by brentp »

that could work, but it would really prefer a square wave.

How about creating a simple 555 timer circuit to feed a signal to it?

Brent
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Luca Lagonigro
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I read on the net someware th

Post by Luca Lagonigro »

I read on the net someware that the VR signal is relly a sine with variable amplitude and frequency, due to the Variable Reluctance nature ofthe sensor. Square wave will work, at least this is what B&G says in their MJL site. In both cases sine or square the signal MUST cross ground reference and have every 35 cicles 1 "pause".

To stimulate the edis module you need a 36-1 signal, with a simple N555 (afaik) you can get a simple square wave but no missing tooth.

EDIS will not trigger TDC and I belive it will not fire the coils. I'm not sure but I think not even LHM (Limp Home Mode) will work with no TDC reference.

In B&G site there is the code to make a VR signal generator from a 68HC908 microprocessor, unfortunately it is written for a QT4 version. I don't have any programming experience so it is impossible for me to understand if the code can be ported to a KX8

Luca

brentp
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simulate PIP signal

Post by brentp »

Sorry, I missed the part about feeding the EDIS module. Acutally what I meant was to simulate the PIP signal that feeds into the MJLJ from the EDIS module. What you would be able to do with this is verify the SAW pulse is being generated (using an oscilliscope), and also verify the software processing of the PIP & SAW signals via the runtime display.

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Luca Lagonigro
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Did U tried? I've the O-s

Post by Luca Lagonigro »

Did U tried?

I've the O-scope and tomorrow I'll bring a function generator home, we'll see if I can simulate the PIP.

Wich one is the PIP waveform in this graph?

http://www.picotech.com/auto/waveforms/ford_edis.html

brentp
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The red signal. on the MJLJ,

Post by brentp »

The red signal. on the MJLJ, what you should see is the SAW pulse happening right after the end of the PIP signal, and the SAW pulsewidth should vary based on the configured ignition advance. the shorter the SAW pulsewidth, the greater the ignition advance.

Brent
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Luca Lagonigro
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Brent, I've made it work with

Post by Luca Lagonigro »

Brent, I've made it work with a square wave signal (2Vrms ˜30Hz) at the PIP input.

I think there is something wrong with my PIP input circuit because I had to feed the processor directly, I had no time to look at it closely tough.

Is there soemone else with a built board? I think we should collect some Oscope screenshots to be used as reference during testing.


brentp
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Try raising the voltage on th

Post by brentp »

Try raising the voltage on the signal - look at the schematic and you'll see how input circuit works with the 5.1 zener diode and transistor.

Screenshots would be good, but I only have a CRT based one. if someone has a software based o-scope, that would be great.

Brent
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Luca Lagonigro
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I've made the weird idea work

Post by Luca Lagonigro »

I've made the weird idea work, I've used a Car Audio Amplifier (DC/DC) with a 36-1 signal fed by a CDP to the EDIS VRS+/-.

The Amp has to be connected in bridged mode to accomplish the trough 0 waveform. Some load need to be connected to the EDIS coil output to get the waveform on the Oscope, I've used 1K resstor I had on the table it worked fine.

Other than that the signal I used was a 9KHz, I've lately (after burning the CD and made all the connections and test) did some math, it turned ou that I was feeding the EDIS with a 15K-ish RPM signal.

Interesting uh? The SAW pulse was appearing / disappearing from the Oscope... I believe I've hitted the red line ;) and the RPM limiter was doing his job.

I'll try again with some different tracks ;).




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