Marti

Marti

The readings I am getting are as follows

New sensor - no continuity between any of the 3 pins

Old sensor - limited continuity between the two outside pins, reading is about 1890ohms, no continuity between the outside pins and the middle pin.

Most information I could find discussed only what the engine might feel like due to the loss of power from a faulty hall sensor or whether the hall sensor had been detected as faulty by the hammer. It would be good to tell if a hall sensor was faulty with just a multimeter - assuming they have a consistent pattern that can be measured when they go faulty.

Thanks

StratfordShark

ammonman

One wire is DC voltage supply (can't remember if it is +5 or +12VDC), the other is the +5VDC pulse signal returning to the EZK and final wire is the braided shield wire to prevent electromagnetic interference. The sensor get s DC voltage from the EZK. This voltage only makes it to the pickup side of the sensor when the gap in the rotor disk behind the passenger cam gear is in the gap between the voltage source and pick-up sides of the sensor. The 3rd wire (shield aka "drain") is there to direct any stray voltage generated by electromagnetic interference to a suitable ground so that is doean't interfere with the signal voltage. If you have a VERY fast digital multi meter or an analog multi meter you might be able to see the +5VDC signal coming from the pickup side of the sensor. Best is to use an oscilloscope to view the signal pulse to verify function.

Mike

John Speake

The supply voltage from the EZK is 5v. It is a semiconductor device so resistance readings are pretty worthless.

Marti

Bedfordman

the Hall Sensor failure mode is to retard the ignition (6 degree I think)
rather than unplug, drive the car and try to feel any difference, as a testing strategy for an installed Hall Sensor: could a good old Timing Light / Strobe show this up on the timing marks?

Peter

FredR

Peter,

No idea what prompted you to resurrent this thread but disconnecting the sensor should result in a "feel" that something is "different" if the system is working correctly and that depends on the sensitivity of the test driver. If one does not feel any difference then that tells you that either the Hall sensor is dead or a knock sensor has gone south as both have the same effect.

As to the timing light one should be able to see a clear difference however I am not sure if the programmed retard impacts the idle map- I have a feeling it does not for some inexplicable reason. You would probably have to spin the motor at a certain rpm point - say 2k rpms and test at the same engine speed/load factor after disconnection. Helps if one has the timing tables from the cruise map to know what one is looking for. The problem then is at light loads the advance is greater so not convinced this would be a viable approach.

Of course the superior way to know if the Hall sensor is working is to have ST2 and PEMS fitted- that tells one immediately whether they are viable [or not]. .

John Speake

The 6 degrees retard is not applied at idle or moderate revs at light engine load. It's purpose is the protect the engine from damage at high load and higher rpm if the sensor is detected as faulty.

The sensor may test OK with a 'scope when the engine is at rest. But if the insulation of the sensor has cracked and fallen away, when the insulation rubs against the block this will create electrical noise and retard is activated.

Zirconocene

Well, so long as we're already into walking dead threads, here's a fun article I found on testing which might be applicable to someone in the future: https://www.thesamba.com/vw/forum/vi...c.php?t=701391

It will likely only test basic functionality but may be useful to someone.

Cheers

Bedfordman

Thanks, John & Fred. I got such good results from Knock Sensors and CP Sensor replacement. Was wondering if Hall unit would be worth change. Insulation / connector on my Hall Sensor OK, so, will leave as is, for now.

systemsc

A Hall Sensor, as used by Porsche during the late '80s & early '90s engines with distributor spark systems, provided TDC info for cylinder number one. This when combined with the knock control function allowed for timing control (retard)
for selective cylinders that developed knock data. Those cylinders were retarded up to a maximum of nine degrees in three degree increments. Once the knock system no longer detected a knock, the original timing would be restored.
If the Hall Sensor failed, lacked a signal, or the knock control system failed, all cylinders are retarded by six degrees above 3500 RPM. The reference is WSM 493.421 page 2-18.