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Trigger errors with VR sensor

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Hi guys,

I have been tuning a car fitted with an Elite 1500 and a VR crank sensor on a 36-1 wheel. With the default arming threshold in the Haltech software, the engine would only rev to 3000 rpm before misfiring and counting trigger errors. By lowering the arming threshold as RPM increases, the engine continued to rev higher. I continued to lower the arming threshold but the engine still misfired around 4700rpm. The arming threshold at that point was now at 0.5V which seems unusual so I didn't go any lower.

Upon looking at the signal through the built in scope, it seems that at 3000rpm, the first tooth after the missing tooth was around 1/2 the voltage compared to the rest of the teeth (See pics attached). This problem didn't occur at 1500rpm which makes me think the problem gets worse as RPM increases and occasionally this tooth gets missed, causing an error.

Has anyone experienced this before? VR sensor and wheel were part of a kit so they should be compatible. Air gap was set at 0.020" as per instructions. Tried filter levels 0, 1 and 2 with 2 being the best. Eventually changed to a hall effect sensor and all trigger issues were resolved.

Cheers, Dean

Attached Files

hello, the polarity of the sensor looks incorrect, i would recommend reversing the polarity of the sensor and reset the base timing. and reset the arming thresholds to where they were. the reason for this is because the rising voltage should slope more horizontal and the falling should be almost a straight line (no curve) ""

Are you sure you don't have a pull-up resistor on that signal? It doesn't look symmetrical like I would expect.

The polarity of the sensor was wired correctly according to the markings on the sensor. Timing was stable as rpm increased. Wouldn’t the timing drift as rpm increases if the polarity was wrong? I will try swapping polarity in future just to verify this.

The pull up resistor was disabled. I agree that it doesn’t looks symmetrical but I assumed that this was the build in scope clipping the negative side of the signal

change the polarity just inverts the signal. So which edge is used will change (so you need to re-verify TDC with a timing light)