Know it all Boffins please

[PINBALL]

Whats a HALL SENSOR and what does it do ?

Also when it fails what are the consequences please.

My 02 - E320 CDI is experiencing power surges when chiefly either de-accelerating or on low 30 mph cruise controlled when going downhill without pulling or under load.

My indie is second guessing its the hall sensor, as he said its got an after market one fitted - prob off Ebay by previous owner.

Any 2nd guesses always welcome to broaden the mind on where to check further - thanks.

Wish Malcolm was still around - I really do miss his always helpful input.

 

[Frosty149]

A hall sensor is a relatively small, sealed, component the communicates electronically (by voltage variations or simple switching) rotational speed and position - used in ABS systems, tachometers and the most likely application for your question, ignition timing and variations therein.
Think rotating small individual magnets on a disk, attached to the end of a shaft, a metallic strip in proximity, is acted upon by the magnetic forces and this is communicated as an electrical signal to the ecu.
A bit simplistic, but, hopefully makes some sense.

 

[mikestrivens]

Here is a good description:

https://en.wikipedia.org/wiki/Hall_effect_sensor

 

[Craiglxviii]

Hall sensor- the recording head in a VCR or tape deck.

 

[LostKiwi]

Hall effect sensors are typically used in ABS sensors and crank position sensors.
Can't see either of those causing the effects you're seeing?

 

[Westheath]

My 02 - E320 CDI is experiencing power surges when chiefly either de-accelerating or on low 30 mph cruise controlled when going downhill without pulling or under load.
Any 2nd guesses always welcome to broaden the mind on where to check further - thanks.

.

Torque converter.

 

[JohnArnoldBrown]

Hall sensor- the recording head in a VCR or tape deck.

Really? I find that very surprising. I could imagine a Hall effect playback head.