EVAP System Through 09.06
Fuel/EVAP System, Checking for Leaks
=> [ Fuel System Leak Test ]
=> [ EVAP System Overview ]
=> [ 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 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 breather line.
- Connect measuring hose - G - from the evaporative emissions tester (KLI 9210) to the adapter hose (KLI 9210/55-2).
- Set the valve - D - to "Hold".
- Connect the evaporative emissions tester (KLI 9210) to the vehicle.
- Start engine and run at idle speed.
- Select the Guided Functions operating mode on evaporative emissions tester (KLI 9210).
- Select the "Check tank ventilation system for leaks" guided function.
- Activate test.
- While the test runs, observe pressure gauge on the evaporative emissions tester (KLI 9210).
• The LDP (V144) must pump the fuel system pressure up to at least 7 in. H2O (17 mbar).
The minimum pressure is not reached, but the pressure reached does not decrease:
- Switch ignition off and perform pressure retention test. If no decrease in pressure is observed: Check the LDP (V144) vacuum supply. Refer to => [ Leak Detection Pump, Checking Vacuum Supply ].
The minimum pressure is not reached and the pressure reached decreases immediately:
- Clamp off hose to the EVAP canister purge regulator valve (N80) with hose clamp (3094) - arrow -.
- Repeat the test. If minimum pressure is not reached: Replace the EVAP canister purge solenoid valve 1 (N80).
The minimum pressure is not reached again and the pressure reached decreases immediately:
- Leak in fuel system, perform "fuel system leak test". Refer to => [ Fuel System Leak Test ].
If the minimum pressure is reached, switch ignition off.
The valve in the LDP (V144) is now closed and the pressure is maintained.
- Observe pressure gauge:
If the pressure does not decrease, perform a pressure retention test to locate any possible pinhole leaks.
If the pressure decreased, clamp off hose to EVAP canister purge regulator valve (N80) with a hose clamp (3094) - arrow -.
- If pressure now no longer falls, replace the EVAP canister purge regulator valve (N80).
If the pressure still decreases, perform "fuel system leak test". Refer to => [ Fuel System Leak Test ].
Pressure Retention Test
- Set the valve - D - to "Test". Increase the pressure up to 10 in. H2O (25 mbar).
- Observe the 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 the pressure is not maintained for 5 minutes, the leak should be localized as follows:
- First check the EVAP canister purge regulator valve (N80) for leaks. Clamp off hose to the EVAP canister purge regulator valve (N80) with 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 the pressure still decreases, perform "fuel system leak test". Refer to => [ Fuel System Leak Test ].
After completing the work, perform the "Check tank ventilation system for leaks" guided function using the.
Fuel System Leak Test
Test Conditions
• Procedure for "checking fuel system for leaks" has been performed. Refer to => [ Fuel/EVAP System, Checking for Leaks ] Fuel/EVAP System, Checking for Leaks.
• Evaporative emissions tester (KLI 9210) with adapter hose (KLI 9210/55-2) still connected to vehicle
- Connect the evaporative emissions tester (KLI 9210) to the vehicle battery.
- Remove rear right wheel housing liner.
- Clamp off hose between the Leak Detection Pump (LDP) (V144) => [ (Item 8) ] and air filter - arrow -.
- Set the valve - D - to "Test".
- Observe the 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).
- 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 the pressure no longer decreases, replace the LDP (V144).
If the pressure is not maintained for a minimum of 5 minutes or if no pressure is built up, localize the leak as follows:
- Fill fuel system with smoke by setting 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 fuel system lines and hoses for 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.
• To check fuel pump and fuel filter flange, the assembly openings in the vehicle interior must be opened.
- Replace any leaking hoses or components.
After completing the work, perform the "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
Leak Detection Pump, Checking Vacuum Supply
Special tools, testers and auxiliary items required
• Turbocharger tester (VAG 1397A)
• T-piece (251 201 346)
• 6 mm 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.
- 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.
- Activate test.
- While the test is running, observe display on the turbocharger tester (VAG 1397A).
• The pressure must pulsate and must not rise above 0.700 bar (absolute pressure) 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.