EVAP System Through 08.06
Fuel/EVAP System, Checking for Leaks
=> [ EVAP System Overview ]
=> [ Leak Detection Pump, Checking Pressure Build up ]
=> [ Leak Detection Pump, Checking Vacuum Supply ]
Special tools, testers and auxiliary items required
• Evaporative emissions tester (KLI 9210)
• Hose adapter (KLI 9210/55-2)
• Vehicle diagnosis, testing and information system (VAS 5051B), (VAS 5052) or (VAS 5053)
• Hose clamps up to 25 mm diameter (3094)
Test Conditions
• A leak was detected by the Leak Detection Pump (LDP) (V144).
• Guided fault finding was performed with the vehicle diagnosis, testing and information system.
Evaporative Emissions Tester (KLI 9210) Preparation:
• Depending on the version, the appearance of the evaporative emissions tester (KLI 9210) may vary.
- Check the evaporative emissions tester (KLI 9210) to see if there is enough fluid in the smoke generator.
- Set the valve - D - to "Hold".
- Open the nitrogen bottle - H -.
- Connect measuring hose - G - to self-test connection - B -.
- Set the valve - D - to "Test".
- Using pressure reducer - J -, adjust the pressure to 10 in. H2O (25 mbar).
- Set the valve - D - to "Hold".
- The pressure must now be maintained a minimum of 2 minutes. If the pressure is not maintained, check the tester.
Fuel System, Checking for Leaks
- Remove the rear engine cover in - direction of arrows - if applicable.
- Disconnect the breather line - arrow - from the Evaporative Emission (EVAP) canister purge regulator valve (N80) in the engine compartment.
- Connect the adapter hose (KLI 9210/55-2) - A - as shown between the EVAP canister purge regulator valve (N80) and the breather line.
- Connect measuring hose - G - from the evaporative emissions tester (KLI 9210) to the adapter hose (KLI 9210/55-2).
- Connect the evaporative emissions tester (KLI 9210) to the vehicle battery.
- Connect the evaporative emissions tester (KLI 9210) to the vehicle.
- Start engine and run at idle speed.
- Select the OBD operating mode on evaporative emissions tester (KLI 9210).
- Now select diagnostic mode 8 "Tank leak test".
- Mark "Tank leak test" entry and press right arrow button > to activate the test.
• When diagnostic mode 8 "Tank leak test" is activated, leak detection pump and EVAP canister purge solenoid valve 2 (N115) are closed for a maximum of 1000 seconds. The EVAP canister purge regulator valve (N80) is not activated. The entire system is now closed.
• If the Engine Control Module (ECM) stops the test, it can be reactivated by stopping the engine and restarting.
- Set the valve - D - to "Test". The fuel system is now filled with nitrogen.
- Observe pressure gauge - C - and flow meter - E -. The fuel system is filled if the flow quantity decreases and the pressure increases to 10 in. H2O (25 mbar).
• Depending on the level in the fuel tank, this procedure may take up to 3 minutes.
- After the pressure has stabilized, set the valve - D - to "Hold".
• After 5 minutes the pressure must not drop below H2O (20 mbar) drop.
If no pressure decrease can be determined, end diagnostic mode 8 and check the LDP (V144) pressure buildup. Refer to => [ Leak Detection Pump, Checking Pressure Build up ].
If pressure does not build up or if positive pressure is not maintained for at least 5 minutes, locate leak as follows:
Allow engine to continue running in idle - with diagnostic mode 8 activated -.
- First check the EVAP canister purge regulator valve (N80) for leaks. Clamp off the hose to the EVAP canister purge regulator valve (N80) with a hose clamp (3094) - arrow -.
- Repeat pressure test by resetting the valve - D - to "Test".
- Observe pressure gauge and flow meter. The fuel system is filled if the flow quantity decreases and the pressure increases to 10 in. H2O (25 mbar).
- After the pressure has stabilized, set the valve - D - to "Hold".
- If pressure now no longer falls, replace the EVAP canister purge regulator valve (N80).
If pressure still drops:
- Reset the valve - D - to "Test".
- While fuel system is being filled, press smoke generator button - I - for approximately one minute.
The fuel system is now under pressure and filled with smoke.
- Check all visible fuel system lines and hoses for any escaping smoke. Also check the fuel tank cap.
• Illuminate components and hoses with a strong flood light, the smoke will be more visible.
• To check for leaks at accessible locations, also use ultrasonic measuring device or commercially available leak detection spray.
• Depending on how long fault finding lasts, smoke generator button may have to be pressed again. This ensures there is enough smoke present in the fuel system.
If no malfunctions are detected:
- Remove rear right wheel housing liner.
If smoke comes out of the air filter:
- Clamp off hose between the EVAP canister purge solenoid valve 2 (N115) and air filter - arrow -.
- Observe the air filter. If no smoke comes out of it now, the EVAP canister purge solenoid valve 2 (N115) leaks. Replace the EVAP canister purge solenoid valve 2 (N115).
If smoke still comes out of the air filter:
- Clamp off hose between the LDP (V144) and air filter - arrow -.
- Observe air filter. If no smoke comes out of it now, the shut off valve in the LDP (V144) leaks. Replace the LDP (V144).
If no smoke comes out of the air filter:
- Check all fuel system components and hoses for escaping smoke.
To check the fuel pump and fuel filter flange, the assembly opening in the vehicle interior must be opened.
- Replace any leaking hoses or components.
After completing the work, perform "Check tank ventilation system for leaks" guided function using the.
EVAP System Overview
1 - Evaporative Emission (EVAP) canister
2 - Adapter hose (KLI 9210/55-2) installation location
• With leak test in fuel system.
3 - EVAP canister purge regulator valve 1 (N80)
4 - Vent line
• To intake manifold.
5 - Solenoid valve
• For Leak Detection Pump (LDP) (V144).
6 - Vacuum line
• To intake manifold.
7 - Air filter housing
• For LDP (V144)
8 - Leak Detection Pump (LDP) (V144)
9 - Fuel tank
10 - Fuel cap
11 - EVAP canister purge regulator valve 2 (N115)
12 - Pressure retention valve
A - Clamp off here
• With leak test in fuel system.
• To check EVAP canister purge solenoid valve 1 (N80).
B - Clamp off here
• With leak test in fuel system.
• To check EVAP canister purge solenoid valve 2 (N115).
C - Clamp off here
• With leak test in fuel system.
• To check LDP (V144).
Leak Detection Pump, Checking Pressure Build up
Test Conditions
• Evaporative emissions tester (KLI 9210) with adapter hose (KLI 9210/55-2) connected to vehicle.
• Valve - D - is at "Hold".
• Diagnostic mode 8 ended and vehicle is running at idle
Fuel system must have no pressure for this test. To release residual pressure, proceed as follows:
- Briefly open the quick release coupling - arrow - on the adapter hose (KLI 9210/55-2) to release pressure in the fuel system. The pressure gauge - C - must drop to 0 in. H2O.
- Select the Guided Functions operating mode on the evaporative emissions tester (KLI 9210).
- Select the "Check tank ventilation system for leaks" guided function.
- Activate test.
- Observe pressure gauge while test is running.
- The Leak Detection Pump (LDP) (V144) must pump the fuel system pressure up to at least 7 in. H2O (17 mbar).
- If the pressure is not reached, check the LDP (V144) vacuum supply. Refer to => [ Leak Detection Pump, Checking Vacuum Supply ].
- If the fuel system has no leaks and the LDP (V144) vacuum supply is OK, replace the LDP (V144).
Leak Detection Pump, Checking Vacuum Supply
Special tools, testers and auxiliary items required
• Turbocharger tester (VAG 1397A)
• T-piece (251 201 346)
• 6mm diameter hose
• Leak Detection Pump (LDP) (V144) installation location: Under wheel housing liner in right rear wheel housing.
- Remove rear right wheel and wheel housing liner.
- Loosen the Evaporative Emission (EVAP) canister bolts => [ (Item 14) Bolt ] EVAP System Assembly Overview and lower it so the vacuum line is more easily accessible.
CAUTION!
Support the EVAP canister so it does not hang by the hoses and lines. This prevents damage.
- Remove vacuum line - 1 - from the LDP (V144).
- Connect the turbocharger tester (VAG 1397A) with T-piece and 6 mm diameter hose between the vacuum line - 1 - and the LDP (V144) - 2 -.
- Switch on measuring range I (absolute pressure measurement).
- Connect vehicle tester and start engine.
- Select Guided Functions operating mode on vehicle diagnostic tester.
- Select "Check tank ventilation system for leaks" guided function.
- While the test is running, observe display on turbocharger tester (VAG 1397A).
• The pressure must pulsate and must not rise above 0.700 bar during the test.
- If the pressure rises above 0.700 bar during the test, the vacuum supply is too low. Check vacuum line to intake manifold for kinks or blockages.