With Generic Scan Tool
Fuel Injectors For Injection Quantity And Proper Seal, Checking
Recommended special tools and equipment
- VAG1348/3A remote control with VAG1348/3-2 adapter cable
- V.A.G 1602 tester for quantity of injected fuel
Without illustration:
- VAG1594A connector test kit
Test requirement
- Fuel pressure must be OK, check, fuel pressure regulator and retaining pressure, checking. Testing and Inspection
Test sequence
CAUTION: Fuel system is under pressure! Before opening system, place rags around the connection point. Then release pressure by carefully loosening connection.
To reach the fuel rail (fuel distributor), several work steps are required which are described in the following for vehicles with manual transmission (without Secondary Air Injection - AIR-); there are only minor differences in the work procedure for vehicles with automatic transmission (with Secondary Air Injection -AIR-).
- Loosen air guide at points designated by arrows and remove air guide.
Next, several hose connections must be disconnected:
- Maintain absolute cleanliness.
- After test, replace clamps with new ones and secure correctly again.
1 Remove Wastegate Bypass Regulator Valve -N75- from fuel rail; hoses remain connected.
2 Disconnect connector at Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-.
3 Disconnect connector at Recirculating valve for turbocharger -N249-.
4 Open the clamp indicated at recirculating valve and disconnect hoses.
5 Open the clamp at fuel pressure regulator and disconnect hose.
6 Disconnect connectors from fuel injectors at cylinder bank 1 and cylinder bank 2.
7 Open clamp and disconnect hose (via this hose, vacuum is supplied as necessary to the mechanical recirculating valve).
8 Open the clamps indicated and disconnect hoses. Hoses lead to intake side of turbocharger bank 1 and bank 2 respectively.
9 Open the clamp indicated and disconnect hose (via this hose, fuel vapors are added to intake manifold).
10 Open screw plug briefly at fuel rail (supply line) to release pressure. Use a clean rag to absorb exiting fuel. Then close screw plug tightly again.
11 Unscrew fuel rail from intake manifold (see arrows). (Tightening torques for bolts: 10 Nm).
- Lift fuel rail with fuel injectors off intake manifold and support it.
NOTE:
- Once the fuel rail has been lifted, check whether the fuel injectors are properly secured to it.
- Individual fuel injectors may possibly loosen from the fuel rail during lifting and remain inserted in intake manifold. In this case, reinstall fuel injectors correctly on fuel rail. Also, always observe notes below.
- Connect test box to control module wiring harness, connect test box for wiring test. Test Box, Connecting For Wiring Test
- Set test box in vehicle interior.
Checking proper seal
- Bridge terminals 1 and 65 at test box using adapter cables from VAG1594 connector test kit (this step supplies Ground -GND- to one side of relay coil of Fuel Pump -FP- relay).
NOTE: After bridging, Fuel Pump (FP) will run continuously, even with engine not running for the following reason: Fuel Pump (FP) relay supplies continuous B+ via central electronics. Fuel Pump (FP) relay receives minus via the cable bridge in test box.
- Check proper seal of fuel injectors (visual inspection). With Fuel Pump (FP) running, only 1...2 drops per minute may drip out per injector.
- If fuel loss is greater, turn off fuel pump (remove cable bridge) and replace the malfunctioning fuel injector; also always observe notes below.
Checking injection quantity
- Insert fuel injector to be tested in a measuring glass from VAG1602 injection quantity test device.
- Connect one terminal of fuel injector to engine Ground (GND) using an adapter cable and an alligator clip from VAG1594 connector test kit.
- Connect the second terminal of fuel injector to B+ using VAG1348/3A remote control, VAG1348/3-2 adapter cable and assisting cable.
Make sure that the test box is located in the vehicle interior.
- Bridge terminals 1 and 65 at test box using adapter cables from VAG1594 connector test kit (this step supplies Ground -GND- to one side of relay coil of Fuel Pump -FP- relay).
Fuel Pump (FP) must run.
- Operate VAG1348/3A remote control for 30 seconds.
- After all three fuel injectors of one cylinder row have been activated, place measuring glasses on an even surface.
Specified value for each fuel injector: 135 ... 165 ml.
- If measured value of one or more fuel injectors is outside of specified range, switch Fuel Pump (FP) off (switch ignition off) and replace faulty fuel injector, also always observe notes below.
- Repeat test at fuel injectors of second cylinder row.
- If the measured values of all fuel injectors are outside the specified range, check fuel pressure. Testing and Inspection
NOTE: Also check spray pattern when checking injection quantity. Spray pattern must be the same for all injectors
Notes for installing fuel rail and fuel injectors:
Installation of fuel rail with fuel injectors is the same in reverse order. Observe the following points when installing:
- Replace O-rings at all opened connections. (Never remove plastic cap from valve head to replace front O-ring - lift O-ring off over plastic cap).
- Lightly lubricate O-rings with clean engine oil.
- Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining clips.
- Place fuel rail with secured fuel injectors onto intake manifold, and apply uniform pressure to press it in.
- Replace clamps with new ones and they must then be installed securely.