Technical > Wiring & Sensors

Several Wiring Questions

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Sanjuro:
Alright guys, I got the thing finished and scoped:





Rob you are right, we do get this funny spike even though I raised the missing tooth gap.  Hopefully like the wiki said v3.3+ hardware can handle it:



As it turns out, all I had to do was slope the gap...  next time!

rob@vems.co.uk:
The thing you need to watch for is not the voltage spikes the LM1815 chip doesnt trigger on peaks it triggers on the point where the signal crosses zero.  With 60-2 we have seen the 'zero' point rise above 0v, so what actually happens is that the point at which the crank trigger voltage falls below 0v changes.  The result is that you can end up with the ignition timing being different on one side of the wheel to the other.  One 60-2 someone posted was so bad that the trigger signal just stopped working over a certain RPM.  Athough that was a bad, out of round, home made trigger wheel from what I could see.

If you take a look at the modern 60-2 wheels you'll see that the teeth and gaps are only a few millimeters high, and the missing "tooth" is actually a very long tooth rather than a very long gap, so the trigger material stays close to the VR sensor - this way if any noise gets into the sensor circuit it just adds to the peak voltage, rather than causing a negative voltage to go high (which can cause a false trigger if the noise spike is high enough to take the voltage over 0v).

Early Renault triggers seemed to take the voltage spike out but having a solid tooth as long as the missing tooth gap, with this the ECU sees just two very long gaps and runs happily.

GintsK:
Especialy I had problems with small diameter 60-2. Teeth are close each other except missing part which then cause a huge signal without zero crossing .
It is good idea to use Hall sensors for small ones.

e.g. BMW have two modifications of small 60-2. With hall missing gap is like on drawing above. But when VR sensor used - filled more than half of depth.

rob@vems.co.uk:

--- Quote from: Sanjuro on March 04, 2009, 12:12:40 pm ---As it turns out, all I had to do was slope the gap...  next time!

--- End quote ---

Or have a massive tooth rather than a gap.
Next time a 36-1 or have 3 teeth and use a cam sync ;)

Good work on publishing the results there.

Denmark:
how did the triggerwheel end up looking like, if you changed the design in the gab?

I alctully have a bit of cranking trigger errors on one of the older impreza´s i made ,that is even with the 36-1 wheel i made,but that is also rather small ,around 80mm in diameter,and the gab is just a missing tooth,so i was thinking if that would benefit froma raised gab also??

/skassa

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