Fuel Injection Volume, Leakage and Spray Pattern, Checking
Fuel Injection Volume, Fuel Injector Leakage And Spray Pattern, Checking
Requirements
- Fuel pressure OK
Preparation
- Remove intake air duct between air cleaner housing and throttle valve.
- Remove engine cover.
- Remove accelerator pedal cable at bracket.
- Remove ball joint at connecting linkage for cruise control.
- Move accelerator pedal cable over cruise control vacuum unit toward rear.
- Disconnect vacuum hose for cruise control vacuum unit.
- Disconnect vacuum hose from fuel pressure regulator.
- Disconnect harness connector for engine coolant temperature sensor (blue connector).
- Disconnect harness connectors for knock sensors.
Remove cable ties or retaining straps as necessary.
- Disconnect connector for Intake Manifold Tuning (IMT) valve.
- Disconnect harness connector for air control valve for fuel injectors.
- Disconnect harness connectors from fuel injectors.
Remove cable ties or retaining straps as necessary.
- Remove fuel rail from intake manifold and lift off together with fuel injectors.
- Disconnect hose from air control valve for fuel injectors.
- Connect VAG1598/19 test box to wiring harness connector for Engine Control Module (ECM).
Checking fuel injector leakage
- Using adapter cables from VAG1594 connector test kit, connect jumper wire between VAG1598/19 test box terminals D11 and A4 (to actuate fuel pump relay).
- Switch ignition on.
- Visually check fuel injectors for leaks.
- With the fuel pump running, no more than 1 to 2 drops per minute may drip from the fuel injectors.
- Switch ignition off.
If fuel leakage is greater than 1 to 2 drops per minute:
- Stop fuel pump (disconnect jumpered connection on VAG1598/19 test box) and replace faulty injector(s).
- Install fuel rail.
- Check readiness code. If DTC memory has been erased, generate new readiness code.
Checking fuel injection volume
NOTE: Before removing fuel injectors, release fuel pressure by briefly opening and closing fuel filler cap.
- Remove fuel rail
- Insert fuel injector to be tested into measuring container from VAG1602 fuel analyzer.
- Switch ignition on.
Using adapter cables from VAG1594 connector test kit:
- Connect jumper wire between test box terminals D11 and A4 (to activate fuel pump relay).
- Connect jumper wire between test box terminals A2 and E7 (to activate Motronic ECM power supply relay and supply voltage to fuel injectors).
- Connect harness connector for cylinder 1 fuel injector to fuel injector being tested on right cylinder bank (bank 1).
To check fuel injectors for right cylinder bank (bank 1):
- Temporarily connect jumper wire between test box terminals E11 (Ground) and terminal E1 for 30 seconds.
Specified value: 105-115 ml (3.5-3.8 oz.)
- Connect harness connector for cylinder 5 fuel injector to fuel injector being tested on left cylinder bank (bank 2).
To check fuel injectors for left cylinder bank (bank 2):
- Temporarily connect jumper wire between test box terminal E11 (Ground) and terminal E5, for 30 seconds.
Specified value: 105-115 ml (3.5-3.8 oz.)
- Switch ignition off.
If fuel delivery is not OK:
- Switch off fuel pump and Motronic ECM power supply relay (disconnect jumpered connections at test box).
- Replace faulty fuel injector(s).
- Install fuel rail.
- Check readiness code. If DTC memory has been erased, generate new readiness code.
- If fuel delivery for all fuel injectors is not OK:
- Check fuel pressure.
NOTE: When checking fuel injector delivery volume, also check injector spray pattern. The spray pattern must be the same for all 8 fuel injectors.
Installing
Installation of the fuel rail and the fuel injectors is the reverse of removal. Also observe the following special points:
- Replace all O-rings at all connections that have been opened.
To replace the front O-ring, do not remove the plastic cap from the valve head. Slip the O-ring over the plastic cap.
- Lubricate O-rings with clean engine oil.
- Install fuel injectors upright to stop (open connectors must face outward) and secure injectors with retaining clips.
- Place fuel rail with installed fuel injectors into position at intake manifold and press in to stop.
- Insert bolts by hand. Lightly push fuel rail by hand toward intake manifold and tighten bolts to 10 Nm (7 ft lb).
- Check fuel injectors for correct installation position (open electrical connectors face outward).
- Check to see that fuel injector retaining clamps are properly seated.