jp928 wrote:tHERE ARE TWO TYPES = OPTical and Hall sensor. My 92 is optical, mates 94 NB is hall. Externally same, internally different.
jp 92 red
Optical and Hall effect are distinctly different animals, the later magnetic based unit is a Hall effect technology--the optical interrupter early unit is not.
The cam angle sensor was changed from an optical type to a magnetic type when the 1.8 was introduced.
The cam drive and mount is the same from 1990-1997 and the signals are compatible so they interchange
Starting in 1999 the cam angle sensor is gone and replaced with a crank angle sensor mounted behind the crank pulley. The camshaft drive and CAS mount are still there so the sensor can be retofitted for the purposes of a 99-05 engine swap into an earlier car.
The optical unit reads holes punched in a disk while the later unit is magnetic based. In theory the later style is more accurate and offers potentially less spark scatter. Without removing the rear cover they can be recognised by the optical has a flat rear cover and the magnetic has a convex rear cover.
In an MX% the ignition trigger signal rises 70 deg before each TDC (the 4 equal holes) and uses the other two to determine cylinders #1/4 and #2/3 (the primary and waste spark).