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Thread: Evaporation (EVAP) Leak Detection Pump (LDP) Test

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    NostraJackAss Jack@European_Parts's Avatar
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    Evaporation (EVAP) Leak Detection Pump (LDP) Test

    EVAPORATION (EVAP) LEAK DETECTION PUMPS (LDP) Prepare for BIFURCATION! TEST'S!

    Here in this thread we will commence to establish comprehensive testing of the EVAP critical systems & to control GHG's, with a full understanding of the importance of them, while also identifying FOD or Deltree type Tampering by aftermarket tuners.



    Let's consider mechanical design and function of the systems since the RTFB appears to be very weak!


    Leak Detection Pump (LDP) Evap System


    The leak detection pump (LDP) is integrated into the EVAP system and can have two functions. The LDP can:
    Pressurize the EVAP system and detect a drop in pressure that would indicate a leak.
    Function as the EVAP Canister Vent on vehicles that do not have a separate EVAP Canister Vent.
    The LDP is a vacuum-driven, ECM controlled, diaphragm pump. In order to operate, the engine must be running and vacuum applied to the Vacuum Switch.

    Tank Leak Diagnostic Module (DM - TL) Evap System


    The canister purge valve can be actively checked using the Tank Leak Diagnostic Module (DM - TL). For this purpose the electric pump is shortly activated while the combustion engine is running, to build up a minor pressure in the fuel tank and monitor the pressure decay after opening the canister purge valve. Optionally as a quick pass method, the monitoring can be carried out by passively monitoring the fuel mixture deviation when the canister purge valve is opened. If a significant fuel mixture deviation is detected, the purge valve monitor passes. The Tank Leak Diagnostic Module (DM - TL) consists of an electrically operated air pump, an orifice with a defined diameter serving as a reference leak, and a change-over valve switching the air flow between the reference leak and the tank. If neither the pump nor the change-over valve is activated, the tank is ventilated through a bypass in the module.


    Natural Vacuum Leak Detection (NVLD) Evap System


    The system utilizes an engine-off natural vacuum evaporative system integrity check that tests for leaks with a diameter of 0.020 inch while the engine is off and the ignition is off. The natural vacuum leak detection (NVLD) evaporative system integrity check uses a pressure switch to detect evaporative system leaks. The correlation between the pressure and the temperature in a sealed system is used to generate a vacuum in the tank when the temperature drops. If a sufficient temperature drop is detected for a minimum time period, the vacuum level in a sealed system will exceed the threshold to close the NVLD pressure switch. Therefore, if the switch does not close under these conditions, a leak is detected. If the switch closes, the system is considered to be leak-free.


    EVAP System, Checking for Leaks


    The following procedure is used to diagnose EVAP System leaks.
    Special tools and workshop equipment required
    Mighty VAC hand pump tester and vacuum caps or pinch clamps to isolate, in some cases a smoke tester but not preferred!


    EVAP and Fuel Supply System Vacuum hose and line routing diagram as per RTFB

    Leak checking
    – Using a Mighty Vac or Smoke tester, check the Evaporative Emission (EVAP) canister system for leaks.
    If a leak is detected:
    – Check the fuel filler cap seal for damage and for proper installation. Replace if necessary.
    – Check all hose connections of the fuel supply system and replace or repair any leaking lines.
    – Check all hose connections of the EVAP system and replace or repair any leaking lines.
    – Check that the seal under the locking flange is properly tightened on the fuel tank.
    – Secure all hose connections using appropriate fittings for the model type.
    – Replace seals and gaskets when performing repair work.
    – Repair or replace any damaged component.
    If no leaks are found in the EVAP system:
    – 0x01-02-05 or in OBD2 Erase the DTC memory if a DTC was set. Refer to → Chapter „Diagnostic Mode 04 - Erase DTC Memory“.
    – Perform a road test to verify repair.

    If the same DTC does return and no leaks are found in the EVAP system:
    – Check for any related TSB's.
    – Perform the diagnostic test procedure for the suspected component.


    Follow the JPPSG.........
    http://forums.ross-tech.com/showthre...uot-JPPSG-quot

    Use this thread link it is very helpful......

    http://forums.ross-tech.com/showthre...l=1#post127189

    The first thing we must separate in the system to cut through the complication above is this.

    Although EVAP and LDP are considered one system, they are indeed with their own part of the readiness bit & being shared before a car can be set to ready, all sub system shared OBD tests which are split off "must pass".

    So for instance traditionally EVAP was 0x01-04-070 or 150 in bin bits in early cars. ( The VCDS test that commands the N80 )

    LDP was 0x01-04-071 or 153 for bin bits in early cars. ( The VCDS test that commands the leak detection pump )

    http://forums.ross-tech.com/showthre...ut-0x01-08-000

    Some cars supported additional purge or charcoal canister valves, for example the Audi TT and early VW Cabriolet, in addition to the traditional N80 valve in the bay & that most are familiar with.

    Later cars also support additional technology and monitoring with another control unit & that functions to monitor the GHG capture blending process, we will address those at a later part of this thread.

    Let's focus on the first two I aforementioned to get a baseline. EVAP & LDP to simplify.

    EVAP will be N80 purge valve for blending vapors from the fuel tank & that have been remediated by a line from the fuel tank with connected accouterments (such as charcoal canister) inline possibly to the engine bay to engines intake at TV.

    LDP will traditionally use a direct vacuum line from engines intake & post TV & sometimes in conjunction with an auxiliary vacuum pump or reservoir in booster storage & that can create a myriad of problems due to PCV integration etc.

    When seeing DTC's for a small leak or large leak, this is in ref to the LDP's jurisdiction, for example a loose or missing gas cap.
    Some cars will monitor the gas cap & have magnetic switches that command an MIL by DTC's from the instrument cluster 0x17 & that show an additional MIL for gas cap + call up on the CAN/K line or W-CAN respective networks to store a DTC in 0x01 engine This can in some applications deny a readiness bit or any other air leak, vacuum or BOOST!....hence why complete auto-scans should be submitted!

    When seeing codes for EVAP & specified outside a "leak" as exception aforementioned, for MAP sensors or trim reported by the Oxygen sensors "OXS' for air leaks, rich running conditions or cross checks than the 070 circuit or N80 valve is suspect & the zone we start with.

    http://forums.ross-tech.com/showthre...What-Causes-It

    Be advised that you can get an N80 070 test to pass & with no gas cap installed or even vented even if the N80 is stuck open mechanically & due to this it can result in a MAP sensor code if it resides in the intake & do to un-metered air.

    EVAP ANY air leaks in intake or connected to it from for example engine PCV lines for LDP permitted back to tank through other accouterments if failed or an N80 mechanically fails.

    LDP Pumps Air and monitors leaks in fuel tank directly & due to not being able to achieve a target to maintain a threshold to not permit GHG's to enter the atmosphere.

    Consider the fact that if the LDP is pumping air in tank and the charcoal canister or other accouterments fail and permit the LDP to begin to overrun and force PSI up into an intake introducing raw fuel or charcoal contamination to the N80 causing the N80 to stick open.

    You will often read about, hey I just fueled up and my car won't start because it was flooded, it was the N80!
    Not always and often NO IT WASN'T! <<<<<<<<<<<<<< The failed N80 was the result not the cause and shortly after being changed it will fail again when it cant maintain PSI being pushed in or ethanol/charcoal deposits FOD or Deltree tuners FOD!

    What input does anyone have, do you like this so far or is it easily understood, because I am just getting warmed up here & a terrible writer......?
    Last edited by Jack@European_Parts; 05-21-2018 at 10:36 AM.
    European Parts Emporium/Performance / Immobilizer Solutions EPE
    Certified Master Trained NY/BAR/BAD 7076062/ASE/SAE/NASTF Legal Factory Authorized/Licensed GeKo/FaZit # 403738
    Specializing in Custom Services IE: "welding-fabrication" / EPA-SMOG Update or Pass-Thru-Programming / Data Transfer / Immobilizers & OEM Quality Parts
    Above Magic! No Written record, AUTO-SCAN or Appointment = NO HELP!
    www.FixMyEuro.com <<<<<CLICK HERE! or vwemporium@aol.com ( JPPSG & Unverified members need not PM me & Please don't email or call facility for free tech support...use the forum )
    Getting you CONTROL again of your property - TAKE IT! In Conjunction with.........

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    NostraJackAss Jack@European_Parts's Avatar
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    EVAP CRIMP TEST 070 PART ONE of Bifurcation

    Tests at the engine in the bay.........

    Vehicle should not be driven during these tests and don't forget to remove the crimps that could impair the brake booster operation or any auxiliary safety functioning system!

    0x01-04-070 EVAP N80
    ( We are inducing a failure to qualify the system is functional & to verify if FOD!)
    So for this part of test we want to see EVAP System NOT OK!


    Locate N80 and on intake side, crimp the rubber hose with smooth jaw locking pliers or equivalent, also crimp the LDP line, Vent oil CAP & crimp PCV and Brake booster!

    Verify deviation by performing 070 test with VCDS & that you are "unable" to PASS by obtaining & watching the basic setting test FAIL!

    If for some reason it happens to pass....... STOP! FOD! check intake for leaks, PCV and or MAF is okay and correct part number!
    Check ECU for FOD DELTREE TUNER!

    Remove one crimp at a time while qualifying isolation tests for each zone crimped off & to see if a different result happens for each time you run a test in VCDS 0x01-04-070!

    Monitor trims too!

    Proceed........remove crimp intake side of N80 aforementioned & now install to tank side of N80.
    Now remove the N80 connection hose on inlet tank/charcoal side and install a mighty vac or vacuum gauge tester vented to atmosphere.

    Run the test 070 and verify that the N80 will seal the connection under full vacuum of idle, no leaks are acceptable!

    If the valve leaks or remains stuck open, change N80.

    Again!

    Remove one crimp at a time while qualifying isolation tests for each zone crimped off & to see if a different result happens for each time you run a test in VCDS 0x01-04-070!

    Monitor trims too!


    For forced air modified cars, consider installing a one way metal ball valve between intake TV-N80 & to enhance the ability to prevent boost from damaging the N80 valve or charcoal canister!
    FACT : It will make your car faster and cleaner! WIN WIN!

    Vehicle should not be driven during these tests and don't forget to remove the crimps that could impair the brake booster operation or any auxiliary safety functioning system!
    Last edited by Jack@European_Parts; 06-03-2018 at 08:00 PM.
    European Parts Emporium/Performance / Immobilizer Solutions EPE
    Certified Master Trained NY/BAR/BAD 7076062/ASE/SAE/NASTF Legal Factory Authorized/Licensed GeKo/FaZit # 403738
    Specializing in Custom Services IE: "welding-fabrication" / EPA-SMOG Update or Pass-Thru-Programming / Data Transfer / Immobilizers & OEM Quality Parts
    Above Magic! No Written record, AUTO-SCAN or Appointment = NO HELP!
    www.FixMyEuro.com <<<<<CLICK HERE! or vwemporium@aol.com ( JPPSG & Unverified members need not PM me & Please don't email or call facility for free tech support...use the forum )
    Getting you CONTROL again of your property - TAKE IT! In Conjunction with.........

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