audi Workshop Repair Guides

Audi Workshop Service and Repair Manuals

ABOUT US
Checking restrictor in fuel return line > < Checking return flow rate of injectors at starter cranking speed

A4 Mk3

Checking for injectors sticking open
Checking for injectors sticking open
If one of the injectors is sticking open, this means that the injector needle is not closing fully and fuel escapes into the cylinder.
Special tools and workshop equipment required
   
t  Hand vacuum pump -VAS 6213-
  W00-10259
t  Use a return line to make an -adapter-.
Procedure
–  Interrogate and, if necessary, erase event memory using → Vehicle diagnostic tester.
–  Pull off engine cover panel → Chapter.
–  Clean all connections (with commercial cleaning solution or similar) before removing.
  Note
t  Make sure all parts are clean; no dirt must be allowed to enter the fuel system.
t  Check all cylinders in turn.
  Caution
Risk of malfunctions caused by dirt.
Observe → Chapter „Safety precautions when working on the fuel system“.
Start with cylinder No. 1.
  N23-10450
–  Disconnect fuel return hoses from injectors; to do so, press down both tabs and at the same time pull centre piece up to release connection -arrow-.
–  Connect adapter to return line connection of injector to be tested after adapter has been cleaned and blown out.
–  Generate a vacuum of -500 mbar using the hand vacuum pump -VAS 6213-.
If the vacuum reading remains the same for 30 seconds, the injector is OK.
If the injector is faulty, the vacuum reading will fall back to 0 bar within 2 to 3 seconds.
Repeat test if necessary; note drop in vacuum reading on hand vacuum pump -VAS 6213-.
–  Renew faulty injectors → Chapter.
  A23-10539

Checking restrictor in fuel return line > < Checking return flow rate of injectors at starter cranking speed