Re: ATTENTION: All UrQ Owners!

[Robert Houk - SMCC Bos Desktop Hardware <rdh@UrQ.East.Sun.COM>]

   Now since we are talking electrical goodies, let me toss this in.  Last
   weekend I decided I'd fire up the TQC.  Naturally the battery was dead.
    Normally, I'd just throw on the charger wait a while and then go for a
   drive.  But about a month ago I bought a DVM and I decided now's the time to
   play with the Audi.  Dead battery - no starter, no click and I measured 8.5V.
    After a bit of charging, with charger off, float voltage was 12, load
   voltage was 9.5.  Left the charger on overnight.  Float voltage with charger
   on was 14.5, charger off 13.8, on load 11.8.  Battery is 1 year old Audi
   battery.  Measurements were made across the battery terminals.  

      I haven't made the measurement yet but is there a significant voltage drop
   from the battery to the ECU?

      How low can the supply dip before the ECU decides not to fire?

The ECU is apparently fairly voltage-sensitive (more so than most). That,
coupled with Audi's wiring practices . . .

       Anybody ever figure out a separate rechargeable (stiff) power supply for
   the ECU?  

   The reason for all these ECU questions is that almost all of my hard starting
   problems seem to be directly related to the spark plugs not firing.
    Occassionally when my car would not start I'd throw on a timing light and
   OFTEN when the engine is cranking over there would be no spark but when I
   would let go of the key I'd get one flash.  Sometimes the car would be able
   to catch on this, most times not.  The more I ponder this, the more I think
   that the ECU must require a VERY stiff supply - something that the new cars
   do not???????  

'Twould appear to be the case.

       Internally does the TQC MAC-02 use +12VDC? or is the supply regulated
   down to say +9VDC? Are the new car's ECUs based on +5???????

I think the MAC-02 uses two regulated levels, +8 (for analog/sensors? The
pressure sensor is fed +8) and +5 (for the logic).

On my car, the system voltage drops to around 9-10 volts on cranking . . .
The better the voltage to the ECU, the better off you will be.

					-RDH