Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Diode test lamp V.A.G 1527
• ◆ Adapter set V.A.G 1594
• ◆ Test box V.A.G 1598/31
• ◆ Current flow diagram

Check conditions

• ● → Fuse No. 3 must be OK.
• ● The battery voltage must be at least 11.5 V.
• ● Earth connection in plenum chamber OK.
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● If the vehicle is equipped with an air conditioning system, this must be switched off.
• ● Fuel pump relay must be OK , final control diagnosis.
• ● Engine speed sender must be OK, checking .

• ● Hall sender must be OK, checking
  .

Checking activation and voltage supply

• ‒ Remove cover over camshaft housing , Fig.1 .
• ‒ → Pull 4 pin connector off ignition transformer (N152) -arrow-.

• ‒ → Pull plug -arrows- off all injectors.

• ‒ → Connect diode test lamp V.A.G 1527 using aux. cables from V.A.G 1594 to connector contacts of Cyl. 1.
• ‒ Operate the starter and check the voltage supply for No. 1 cylinder injector.
       The LED must flicker
• ‒ Repeat check at the injector connectors for Cyls. 2...4.
• ‒ Switch off ignition.

If the LED flickers on one or several cylinders:

• ‒ → Connect diode test lamp to contact 1 and earth of relevant injector connector.
• ‒ Operate the starter and check the voltage supply for No. 1 cylinder injector.
       The LED must light up
• ‒ Repeat check at the injector connectors for Cyls. 2...4.
• ‒ Switch off ignition.

If the LED does not light up:

• ‒ Check wire between 2 pin connector contact 1 and fuel pump relay (J17) for open circuit using current flow diagram.
       Wire resistance: max. 1.5 ω

If the LED does not light up on one or several cylinders:

• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

• ‒ → Check wiring for open circuit between test box and 2-pin connector referring to current flow diagram.
       Injector 1: Contact 2 and socket 88
       Injector 2: Contact 2 and socket 87
       Injector 3: Contact 2 and socket 85
       Injector 4: Contact 2 and socket 86
       Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another between contacts 2 to vehicle earth and to battery positive.
       Specification: ∞ω
• ‒ Check wiring between connector contacts 1 of injectors for open circuit to one another.
       Wire resistance: Max. 1.5 ω

If no fault is detected in the wiring:

• ‒ Check resistance of injectors
  .

Checking resistance of injectors

• ‒ → Check resistance of injectors between contacts.
       Specification: 12.0...17.0 ω(at room temperature)

Note:

The resistance figures are valid for approx. 20 °C. At higher temperatures the resistance figures will increase.

If the specification is not attained:

• ‒ Remove air cleaner => Page 24-26 , Fig. 2 .
• ‒ Renew defective injector
  , item 7 .

Perform installation of injectors in reverse order. When doing this note the following:

• ◆ Renew O-rings on all injectors and lightly moisten with clean engine oil.
• ◆ Insert injectors vertically and in the correct position into the fuel rail and secure with retaining clips.
• ◆ With injectors secured to fuel rail, fit fuel rail on intake manifold and press in evenly.

• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-20 , interrogating and erasing fault memory.
• ‒ Erase the learnt values and adapt the engine control unit again=> Page 24-128 .

If the resistances are OK and no faults can be detected in the wiring:

• ‒ Replace engine control unit
  => Page 24-121 .

Checking spray pattern and for leaks

Special tools, workshop equipment, test and measuring appliances and auxiliary items required

• ◆ V.A.G 1331 Torque wrench (5...50 Nm)
• ◆ V.A.G 1594 A Adapter set
• ◆ V.A.G 1630 Digital potentiometer
• ◆ Measuring container

Test conditions

• ● The fuel pressure must be in order, checking
  => Page 24-83 , checking fuel pressure regulator and holding pressure.

Test sequence

• ‒ Remove air cleaner => Page 24-26 , Fig. 2 .
• ‒ → Pull 4 pin connector off ignition transformer (N152) -arrow-.

• ‒ → Pull the 4 pin connector off coolant temperature sender (G62) with coolant temperature gauge sender (G2) -arrow-.

• ‒ → Connect digital potentiometer V.A.G 1630 using aux. cables from V.A.G 1594 to connector contacts 3+4 and set connected side to 15 kω.

• ‒ → Pull the vacuum hose off fuel pressure regulator -arrow-.

• ‒ → Disconnect 2-pin connector from camshaft adjustment valve(N205) -arrow-.

• ‒ → Pull plug -arrows- off all injectors.
• ‒ Unclip injector wiring harness on fuel rail.
• ‒ Remove fuel rail complete with all injectors from intake manifold (fuel hoses remain connected)
  => Page 24-12 , item 9 .

• ‒ → Hold a small container under the injector to be tested and fit the connector.
• ‒ Have 2nd person operate starter. Injector must spray in pulses.
• ‒ Repeat check with other injectors ensuring that injector to be checked is only connected.
• ‒ Switch off ignition.
• ‒ Switch off ignition and afterwards check injectors for leaks. No more than
       2 drops/min
  may leak from each injector.

If the fuel loss is greater:

• ‒ Renew defective injector
  , item 7 .

Perform installation of injectors in reverse order. When doing this note the following:

• ◆ Renew O-rings on all injectors and lightly moisten with clean engine oil.
• ◆ Insert injectors vertically and in the correct position into the fuel rail and secure with retaining clips.
• ◆ With injectors secured to fuel rail, fit fuel rail on intake manifold and press in evenly.

• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-20 , interrogating and erasing fault memory.
• ‒ Erase the learnt values and adapt the engine control unit again=> Page 24-128 .