Page 3 of 90

24-2
      
CAUTION! 
     
To operate the engine at starter speed 
without actually starting it (for example, in 
order to test compression), unplug the 
connectors from the output stages for the 
ignition coils and also the connectors on the 
injectors. 
     During some of the tests the control module 
may identify and record malfunctions. The 
DTC memory should therefore be checked 
and (if necessary) erased after completing 
the tests and any repair work that may be 
required. After erasing DTC memory 
generate new readiness code   Page 01
-
105
 . 
     
Always switch off the ignition before 
cleaning the engine. 
     Always switch off the ignition before 
connecting or disconnecting the battery, 
otherwise the engine control module may be 
damaged. 
     Be sure of proper radio code (for vehicles 
equipped with coded anti-theft radio) 
     
Be sure the battery negative (-) cable is 
Pa
ge 3 of 90 Motronic Multi
port Fuel In
jection 
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1 
         
        
        
     
        
        Page 57 of 90

24-48
      
Checking for leaks  
     
-  Bridge sockets 1 and 65 on the test box using 
test leads from VAG1594 A connector test kit. 
(This creates an Ground (GND) connection to 
one side of the fuel pump relay coil.) 
     
Note:  
     Once the socket are bridged the fuel pump runs 
continuously, even if the engine is not running. 
This is because the fuel pump relay receives its 
positive voltage supply via the central electrics. 
The negative voltage supply for the fuel pump 
relay comes via the cable bridge on the test box. 
     
WARNING! 
     
Fire hazard. DO NOT smoke or work near 
heaters or have anything in the area that can 
ignite fuel! 
     
-  Check injectors fuel for leaks (visual check). 
When fuel pump is running, only 1 or 2 drops 
should escape per minute from each injector. 
     
-  If fuel loss is greater, switch off fuel pump 
(remove bridge) and replace faulty injector   
Page 24
-53
 , also observe notes on   Page 24
-
53
 . 
Pa
ge 57 of 90 Motronic Multi
port Fuel In
jection 
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1 
         
        
        
     
        
        Page 59 of 90
24-49
 
    
WARNING! 
Make sure test box is inside of passenger compartment. 
The fuel pump should run.  -  Connect one fuel injector terminal to engine Ground (GND) using test 
cable and crocodile clamp from VAG1594 connector test kit. 
-  Connect second fuel injector terminal to B+ using remote control 
VAG1348/3 A, adapter cable VAG1348/3-2 and auxiliary cable. 
-  Bridge sockets 1 and 65 on the test box using test leads from 
VAG1594 A connector test kit. (This creates an Ground (GND) 
connection to one side of the fuel pump relay coil.) 
Pa
ge 59 of 90 Motronic Multi
port Fuel In
jection 
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1 
         
        
        
     
        
        Page 61 of 90
24-51
      
-  Repeat test for fuel injectors from second bank 
of cylinders. 
     
-  If measured values for all fuel injectors are 
outside tolerance range (specification), check 
fuel pressure   Page 24
-33
 . 
     
Note:  
     When checking the injection quantity, also check 
the spray pattern. The spray pattern should be 
the same for all the injectors. 
      Installation of the fuel rail together with injectors 
is performed in the reverse sequence. The 
following points should be noted when installing:  
     
Replace O-rings at all opened connections. 
(When replacing the front O-ring, make sure 
not to remove the plastic cap from the 
injector head. The O-ring must be pulled off 
over the plastic cap.) 
     Moisten O-rings with clean engine oil. 
Pa
ge 61 of 90 Motronic Multi
port Fuel In
jection 
(MFI
) system, servicin
g
11/22/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.FU04.24.1