From: Wally Plumley [wplumley@bellsouth.net]
Sent: Tuesday, June 04, 2002 5:12 PM
To: 928
Subject: [928] Re: hall sensor

At 04:19 PM 6/4/02, Jay Gary Wellwood wrote:
> >
> > where is this "RPM SENSOR" as they show as a different device than the 
> Hall.
>
>The RPM sensor (or Impulse Sensor) housing - the forward most sensor of
>the two that are back there.  It connects to the wiring harness directly
>under the MAF for the RPM signal.  The other sensor located on the bell
>housing is a mechanic's Tool.  It is the item you see on the Driver's side
>of the Intake - and connects to nothing electrically - it was as mentioned
>a Mechanic's tool - which didn't work very well I'm told.
>
>The Hall has a vey slight input to the LH Unit - and as Wally pointed out
>- the car will run without it.  From what I understand - originally, the
>Hall was to determine the position of the Cam for precise Injection timing
>while the RPM Sensor provides the speed/accelleration input.  If you trace
>the wires out, you'll find will finds that they trace all the way back to
>the Tach for the engine speed signal.


If the EZK control unit detects the absence of the Hall signal, the 
ignition timing is retarded - I think by four degrees.

Wally Plumley
928 Specialists