BMW 328 e36 loosing wheelspeed signal over 152kmh.
656 pulses / 100kmh. So somewhere around 1000 pulses per sec it drops.
Is there a 1khz rc-filter on the wheelspeed input ?
- 2k4 * 220nF = 528 usec time constant (but freq signal can be sensed at partial amplitude, not a sharp filter)
- but it used to be 4k7 * 220nF earlier (that filter definitely won't work for such high-freq signal without a divider: freq >3 times the recommendation)
I would like to change it to 2khz to allow the wheelspeed signal to max speed ( 260kmh )
Which components to change?
- 220nF to 100 nF
- Even if firmware can handle higher frequency, [Recommendation] is divider for more than 10 pulses per wheel rotation (== 354 Hz @255 km/h).
- HALL signal can also be divided by 4 or 8 (elimination of the VR-input conditioning part of the small circuit by disconnecting LM1815's output).
Try lowering sensor signal min length, pulses closer than 6464uS (in your config) are dropped 656 Hz/100kmh ~= 997 Hz / 152km/h which is close to 1.5 mSec pulse time, close enough to be significant, lower it to around 2000 uS and report. Also disable second wheelspeed sensor if its not being used (2nd speed sensor calibration = 0)
- Forgot to write. Tried 2000, 1000 and 0 for the filter an neither made any difference. I´ve also tried disabling the second speed sensor. Didnt have the last log on my laptop..
- Ive also tried Divider 3 and 218 pulses / 100kmh. Much better at low speeds but didnt make any difference to the problem