Fo Orin: Starter Tooth Sensor Question

[Orin]

> You seem to be somewhat familiar with the Audi turbo set-up.
> 
> So--let's see if we can pick their brains a bit. No point in reinventing
> wheels when a reputable mfgr. has done development work, after all !!
> 
> 1. Does Audi use a mag pick-up or a Hall-effect sensor?

Magnetic variable reluctance.

> 2. Does it face the ring gear radially or from one face?

Radially.

> 4. Is it any sort of a "smart" sensor ?? (Any on board digital or analog
> signal processing in the sensor?)

No, same sensors since 80s as far as I can tell.  Difference in part numbers
seems to be concerned with the connectors and/or cable length.

> 5. Do they do any signal processing for this sensor in their ECU??

Simple comparator based circuit on both flywheel teeth and second
'cyl 1' sensor.  Just a Schmitt trigger on the flywheel sensor.
The second cyl 1 sensor uses a percentage of the previous peak
level to compare against with a bleed resistor on the capacitor used
to store the previous peak.

I have the circuits hand drawn and scanned somewhere.

> 6. I take it they use a second sensor for a timing pick-up Does this one
> pick up from "lugs" added to the flywheel, or from something else?? Is this
> one Hall or mag??

It's a pin inserted in the engine side of the flywheel.  

> 7. I also assume they use a third sensor  off the cam or a dizzy shaft to
> get cam position?? Again, Hall or mag??

Hall sensor in the distributor - in fact, the same as the NA engines
use to fire the ignition, only with one window rather than 5.

> I happen to have one of the Bentley service books for the Quattros, so I
> will do some digging too.

It should be in there as long as it's for some turbo model between 84 and 95.

> Also thinking that a useful ECU function might be to "wife and or bozo
> proof" the starter and ring gear-- use a discreet input for a "start"
> command and an on/off output to control the starter solenoid via a relay.
> Do things like not enable the solenoid if the flywheel sensor is picking up
> any engine motion at all, cut juice to the solenoid once the flywheel
> sensor frequency goes above a certain level for a particular length of
> time, refuse to re-energize the solenoid for "X" seconds after it has been
> de-energized (so as to give the starter time to spin down to a full stop).

Hint... most of the Audi ECUs don't energize the fuel pump relay until
they detect a signal from the flywheel sensor.  They also de-energize it
a couple of seconds after the signal stops.  Unfortunately, they also
de-energize it as an overboost or overrev cutoff.

> I'm thinking all of these functions would tend to keep the tooth fairies
> away from the ring gear.

The Audi teeth seem remarkably bozo proof.  Seems to take a hydrolocked
cylinder or broken starter to break them.

Orin.
----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org