KMS MP25 - Page 14

KMS MP25(M)/MA25(M) manual Version 4.2
14
3.2.4.1.1.1 Crank pickup:
You can enable the crank pickup and set the references.
Here you can select if your connected sensor is hall or inductive.
Hall sensor: a current runs through a thin Hall-plate. When this plate is undergoing a magnetic field,
a voltage arises between the two sides of the plate. When a tooth passes the plate the magnetic
field changes.
Inductive sensor: consists of coil around constantly magnet. The change in magnetic field generates
a current in the coil. When a tooth passes the coil with magnetic core the magnetic field changes.
When a tooth is approaching the signal gets stronger. When a tooth is passed the signal gets weaker.
Difference is the Hall sensor generates a Voltage and the inductive sensor generates a current.
TIP: Measure the resistance between two pins by using a multimeter. When sensor is inductive the
resistance should be between 0.5 kΩ and 2 kΩ. When the sensor uses a 3-pole connecter there
should also be the resistance of 0.5 kΩ – 2 kΩ between two pins. The remaining pin is the shield of
the sensor cable. If resistance is not measurable the sensor will be likely a Hall effect sensor.
Warning:
Do not use unsuppressed spark plugs and leads. They can cause
electromagnetic interference.
Crank-type:
The rpm signal has to be delivered by an hall/inductive sensor using a rotating trigger pattern. The
individual pattern types are listed under the pulldown menu. Not all trigger patterns are compatible
with all engine types. Possible combinations are listed in this table. Some trigger patterns are
shown in Appendix 1: Trigger pattern drawings.
When using a 60-2 trigger pattern the maximum engine speed is limited to 12.500 rpm.
When using a Hall-sensor, it is nescessary to use a convertor that will change the Hall-signal into an
inductive signal (exception below). The convertor has KMS partnumber KAC.17.001.
Ref. point:
The reference point (the position of the piston at the moment the first tooth after the missing
tooth/teeth passes the sensor) of the crank pickup sensor can be set between 0 and 180 degrees
before TDC (for most engines recommended between 70-120degree). The position of the reference
point in the software must be checked. Mark the TDC on the crankshaft pulley or flywheel. Check
with a timing light the degrees when igniting on cylinder 1 in TDC with a static engine speed. If the
ignition advance set in the software deviates from the measurement with the timing light, then you
have to correct the reference point in the software.
TIP: set for the complete rpm-range the ignition advance map to 10 degrees. The ignition advance
read out on the software screen will be stable and doesn’t change when your engine speed varies a
bit.
For example, your reference point set in the software is 90 degrees. The ignition advances 10
degrees at 1000 rpm. Checking with the timing light on cylinder 1 gives you 5 degrees ignition
advance. That’s a deviation of 5 degrees which must be corrected on the reference point. The
correct reference point is 90 – 5 = 85 degrees.