audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

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Injection system > < Fuel delivery unit and fuel gauge sender - rest-of-world vehicles (front-wheel drive)

A5

  • Power unit
  • Simos direct petrol injection and ignition system (6-cyl. 3.2 ltr. 4-valve)
  • Mixture preparation system, electronic inj.,Gas
  • Engine control unit

Removing and installing engine control unitJ623
Removing and installing engine control unit -J623-
Special tools and workshop equipment required
t  Hot air blower (220 V/ 50 Hz) -VAS 1978/14--item 1- with nozzle attachment -2- from wiring harness repair set -VAS 1978-
   
t  Small, commercially available vice grip pliers -3- (mole grip)
  Note
  A24-0475
t  The engine control unit -1- is bolted to the protective housing -5-. To make it more difficult to unscrew the shear bolts -4- for locking plate -2-, their threads have been coated with locking fluid.
t  The metal casing has to be removed before the connectors can be unplugged from the engine control unit (e.g. to connect the test box or renew the engine control unit).
Removing
–  When renewing engine control unit, select diagnosis object “Replace engine control unit” in “Guided Functions” on vehicle diagnosis, testing and information system -VAS 5051B-.
–  Switch off ignition and remove ignition key.
  A24-0593
–  Slightly pull off rubber seal in front of nut -1- on plenum chamber cover.
–  Unhook wiring harness -2- from retainers -A-.
–  Remove nut -1-.
–  Pull filler neck -3- with filler pipe out of washer fluid reservoir and through opening in body.
  A92-10087
–  Unscrew bolts -arrows- and take off cover for electronics box.
  A10-10853
–  Release retainers -arrows A- and pull out engine control unit -J623--arrow B-.
  A10-10854
To help prevent unauthorised access to the connectors on the engine control unit, the engine control unit -1- is bolted to a metal casing -5- by means of shear bolts -3 and 4- and a locking plate -2-.
The threads of the two shear bolts -4- which are not screwed into the engine control unit are secured with locking fluid. To unscrew these two bolts, the threads must therefore be heated with the hot air blower.
  A24-0593
The threads of the two shear bolts -3- which are screwed into the engine control unit are not secured with locking fluid. Do not apply heat to the threads in the control unit housing; this is not necessary and would cause overheating of the control unit.
  A24-0593
–  Select settings on hot air blower as shown in illustration, i.e. set temperature potentiometer -2- to maximum heat output and two-stage air flow switch -3- to position 3.
  WARNING
Heating the thread of the locking plate also heats up the shear bolts and parts of the metal housing. Take care to avoid burns. It is also important to ensure that only the thread is heated and none of the surrounding components if at all possible. These should be covered if necessary.
  A24-0476
–  Apply heat to the threads of the shear bolts on the connector side for approx. 25 to 30 seconds.
–  Unscrew shear bolts using vice-grip pliers (see arrow in illustration).
  A24-0594
–  The two shear bolts screwed into the engine control unit do not need to be heated. They can be removed without heating.
–  Detach metal locking plate from control unit connectors.
–  Release connectors on engine control unit and unplug connectors.
–  Take out old engine control unit -J623- and install new engine control unit -J623-.
Installing
Installation is performed in the reverse sequence.
–  After installation, the locking plate must be re-fitted on the engine control unit -J623-.
–  Clean threaded holes for shear bolts to remove any residue from locking fluid. This can be done using a thread tap.
–  Always use new shear bolts.
l  Tightening torque for bolts securing cover of electronics box: 3.5 Nm.
After installing a new engine control unit, the following operation must be performed:
–  Activate engine control unit via vehicle diagnostic, testing and information system -VAS 5051B- in “Guided Functions” mode, “Replace engine control unit”.
  A24-0595

  • Power unit
  • Simos direct petrol injection and ignition system (6-cyl. 3.2 ltr. 4-valve)
  • Mixture preparation system, electronic inj.,Gas
  • Engine control unit

Injection system > < Fuel delivery unit and fuel gauge sender - rest-of-world vehicles (front-wheel drive)