[Jason Rouillard]

I tried without sensor, with filter, with rising/falling and with a signal from my ICM and i has all of time same thing.

Exactly. Keep in-mind, the Tooth Logger and the Composite Logger give different info. The Tooth Logger only shows time in any condition, high or low. So, the longer it is low, the taller the bar, and the longer it is high the taller the bar. Yours is a good example of the effects, and how the timing only shifts, as either high or low signal, Rising or Falling, the duration (time) of the wide teeth and gaps are the same, inverted or non-inverted. A Composite Log would be different info.

Where we see issues ("double bar") with the Tooth Logger is when the signal voltage drifts upwards or downwards in a "wide" space, triggering a high or low early, where there is no tooth (missing). Again, this is either incorrect polarity or setting to read the wrong signal edge. An irregular wheel may read perfectly in any combination where there is insufficient time for the signal to drift high or low early.

Finally, we say "correct polarity" so we know which sensor signal edge will be sharp and most accurate. And "correct edge setting" for the specific conditioner module to read that correct edge, that will not drift timing at high-rpm. Four ways to set up VR, but only one is optimal.

For an irregular wheel such as the GM7x, test your sensor for polarity separately, and connect to the proper VR inputs. Set your Trigger Edge for the specific VR conditioner module you are using. Then set your timing using Trigger Angle, with a timing light.

I reversed the polarities and put my setting to Rising Edge (MAX9926). I did a tooth logger and i has same result.

I checked the voltaage on each wire and one have 0.6V and other 0.06V.

If I understood correctly, the wire with the highest voltage goes to vr+?
If this is correct, my wires were reversed and the original plan did not give the correct information.

Is measuring the voltage on each wire is the right way to know which wire goes where?

Thanks !

[Jason Rouillard]

In my last post, i said i have more voltage on one wire. It's false, both are equal.

How i can know which wire go to vr+ and vr- ? Try and error ? Oscilloscope?

[PSIG]

You can find more info here by searching terms such as "VR sensor polarity test". Using a multimeter or volt meter:

Testing of the two VR pins should show a (+) voltage when a ferrous object approaches, and (-) as it departs. So for example, if you stick the sensor to a wrench magnetically, it should produce a positive voltage when sticking, and a negative voltage when removed, if your meter is connected in correct polarity. The tested positive wire goes to VR1+ and negative to VR1- for crank, and similar for cam. Shield wire goes to one of your Speeduino power ground terminals — not one you have chosen for your sensor grounds.

[Jason Rouillard]

I did the test and i found which wire make + when i stick or remove metal from sensor.

But, i have a gm7x and it have notch so i need to put wire that make + when i remove the metal from sensor ?

If i understand, a notch wheel reverse polarity of sensor ?

[PSIG]

I did the test and i found which wire make + when i stick or remove metal from sensor.

Good, then you know it should make (+) when moving toward metal, and (-) when moving away.

But, i have a gm7x and it have notch so i need to put wire that make + when i remove the metal from sensor ?

No, see above. The notch in the trigger wheel is where the metal is moving away from the sensor, and where the signal should be "going low" (going -).

If i understand, a notch wheel reverse polarity of sensor ?

A sensor in correct polarity will generate (+) voltage moving towards a tooth, and (-) voltage moving away from a tooth (gap or notch). There you have it, three different ways to say the same thing.

[Jason Rouillard]

Tomorrow I will do an chart for next person with same problem. Maybe you will can validate it ?

[PSIG]

Great idea. I'll just put one together with notes right on it.

[PSIG]

While I put the "cheat sheet" together, here are a couple similar images used in the past that may help to explain why we are after a certain combination of settings for VR sensors and conditioners.

Also note that not all specific sensors or "tooth" configurations will have all issues. However, we suggest one combination that works for the vast majority of components and setups. This avoids a confusing page of "if", "but", "except for" statements. "Do it this way, and it works", whether you need it or not.

VR signal polarity & trigger edge.jpg (125.6 KiB) Viewed 246 times

VR_correct_polarity.jpg (41.65 KiB) Viewed 246 times

Correct polarity cam.jpg (83.71 KiB) Viewed 246 times

[Jason Rouillard]

I did the fix, but it's not work.

I put my setting on rising edge with cranking at 0 degree and fix timing at 0 also. I tried to time my engine with timing lamp but timing jumps around 4-5 degrees before top dead center and after top dead center.

I tried to reverse polarity of crank sensor and it was worst...

I made a mark on my crank pulley and engine while my piston 1 was at tdc. My mark on pulley jump before and after the mark on engine.

Why my timing jump like this ? What can cause this if i have good polarity and good setting for trigger setup ?

Thanks !

[jonbill]

I think possible reasons for that would be:
1) loose sensor mount
2) loose trigger wheel
3) decoder error - wiki says gm7x decoder is untested, but that might be very out of date.
4) signal noise leading to false 7th tooth detection. I think this would be coupled with spiky rpm in the log.
5) something else