unstable digital speed information on MXL2

[Hanns Per]

it shows abt. every 10th of a second a different speed around the actual speed. the variance is smaller at lower speed but at abt. 120 kmh it is extreme from 60 to 130. I would like to have a stable info which varies according to actual speed only. I have this more or less since I changed from the Analog speedometer to the MXL2. The installation is as follows: Caterham CSR built 2005, The wheel speed sensor is the original one Schneider XS1N08NA340 (12-24V) on the rear right wheel.  The signal from the sensor is connected to the MBE9A9 + of sensor to the 12V battery and - of the sensor to the chassis. Between + and the signal there is the original 1K 0.25W resistor.

I tried all the different settings in the AIM and MBE and made adjustments to the sensor position but no improvement. 

Thank You for Your help

Hanns Per

 

[aerobod - near CYYC]

Assuming the wheel speed sensor LED activates as expected and the air gap is correct, I would put an oscilloscope probe on the speed sensor output and record the waveform, looking for signal variation and noise.

With my car I had an intermittent failure in the low voltage feed on cylinder number 1 that I traced on the road with a cheap USB oscilloscope, this is the thread I started on that: https://www.lotus7.club/forum/techtalk/good-tool-chasing-intermittent-electrical-issues

[Hanns Per]

Now I found the answer to ma problem, the original Caterham wheel speed sensor is not suited for the MBE ECU, in fact the wiring I made is dangerous and can harm the ECU. Caterham uses the original sensor only for the Tachometer. So I now try to put a Hall effect  sensor like this one GS100502 from ZF Electronics. Somewhat tricky to mount this sensor where the sensor ring is on the CSR. I think of putting it on the Diff side flange of the drive shaft and put a sensor ring there. Anyone knows what the sensor ring specification is for the Caterham dirive shaft. thks Hanns Per