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VCDS output tests - Fuel Injectors , N75 and G40

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  • VCDS output tests - Fuel Injectors , N75 and G40

    Hi

    Just wondered how reliable the output test on a 3B is?

    Ive gone through the tests several times,

    - Fuel Injector 1-5 - no sound, no buzzing
    - Idle Stabiliser Valve (N71) - Hear clicking sound
    - Carbon Canister Solenoid (N80) - Hear clicking sound
    - Wastegate Frequency Valve (N75) - No sound


    Not sure what's up with the injector test, the car runs and is drivable.

    - The N75 doesn't make a sound, Ive tried measuring the contact to the ecu which gives 11-11.5 volt ouput.
    - Nothing happens when I engage the N75 with 12 volts.
    n75_1.jpg

    - Measured the ohm but it goes a bit crazy then stabilize on 15-33 somewhere then suddently to 6-7.
    - The female 2pin contact seems a bit broken in the plastic, should probably change it
    connector1.jpg


    Going to change it just to be sure, is there anything else I could check? Does these fail frequently?
    Ordering one from Audi Tradition to see, might be time to change it anyway before further upgrades.

    ------------

    Ran VCDS some time ago after an hour drive, It feels like its struggling sometimes with 100% throttle engaged over 4000rpm but not always


    00515 - Camshaft Position (Hall) Sensor (G40)
    30-10 - Open or Short to Plus - Intermittent


    Had this fault earlier, reset the codes and was driving , still some struggling but the G40 code hasn't come back..

    Should I change it?

    Got new Bosch F5DPOR plugs, the plug cables looks decent but might change them aswell while Im at it.

    - Lars


  • #2
    Have you confirmed there is continuity between the ecu and the wgfv connector. The last car I looked at had damaged wiring behind the headlamp the wgfv was non-responsive.
    Mike

    http://www.s2-audi.co.uk

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    • #3
      Originally posted by Mikes2 View Post
      Have you confirmed there is continuity between the ecu and the wgfv connector. The last car I looked at had damaged wiring behind the headlamp the wgfv was non-responsive.
      Measured from the sensor going to ecu? not sure if it goes straight there. but 1 on the sensor and 1 pin on the earth-grounding, got 11.2 volt+
      Not sure how I could check it?

      But it might be damaged, but the N75 looks like it need replacement so I bought a new one, I dont think it will hurt in the long run, I can put the old one on the shelf for later anyway.

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      • #4
        The G40 will usually start to fail by going intermittent at a warmer temperature which you won't notice unless you happen to need to do a hot start. Eventually it'll start failing at colder temperatures then completely and the car won't start. I'd recommend replacing it. You used to be able to save yourself a lot of money by reusing the bracket and riveting on a new Hall sensor yourself.

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        • #5
          It did seem like a big job but im not sure if it is or not. hm

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          • #6
            Originally posted by larsaskogstad View Post

            Measured from the sensor going to ecu? not sure if it goes straight there. but 1 on the sensor and 1 pin on the earth-grounding, got 11.2 volt+
            Not sure how I could check it?

            But it might be damaged, but the N75 looks like it need replacement so I bought a new one, I dont think it will hurt in the long run, I can put the old one on the shelf for later anyway.
            Pin 23 at the ecu goes to pin 2 of the wgfv connector. The other (pin 1) goes via fuse 24 to pin 37 of the ecu (+12v), All you've proved is one side of the circuit is showing 12v which it should do since the ecu puts out 12v from that pin to that device along with several others.
            Mike

            http://www.s2-audi.co.uk

            Comment


            • #7
              So how do I measure it?

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              • #8
                With the WGFV off the car, connect a battery across the two pins it should click.

                If not it’s broken

                S2 Coupe 3B Project


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                • #9
                  Originally posted by larsaskogstad View Post
                  So how do I measure it?
                  Ignition off
                  Check continuity (zero ohms) of the two wires from the ECU connector to the WGFV connector.
                  You will need to extend one of the test leads, I have a length of wire with a male pin on one end to plug into the ECU connector.

                  S2 Coupe 3B Project


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                  • #10
                    Just 12v from battery to the 2 pin connecter on the n75?

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                    • #11
                      Originally posted by larsaskogstad View Post
                      Just 12v from battery to the 2 pin connecter on the n75?
                      Yes
                      It’s just a 12v solenoid valve

                      S2 Coupe 3B Project


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                      • #12
                        Yeah tried that earlier, no reaction at all. Looked quite old as well. Going to chanhe it and do an output test.

                        Now I just need to replace the g40 hall sensor. Not looking forward to doing that.

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                        • #13
                          Originally posted by larsaskogstad View Post
                          Yeah tried that earlier, no reaction at all. Looked quite old as well. Going to chanhe it and do an output test.

                          Now I just need to replace the g40 hall sensor. Not looking forward to doing that.
                          Not too bad a job, as it’s a 3B it’s inside the distributor. The trick is to find the right 13mm spanner to access the clamp nut.
                          If I remember right it has to be an open ended one and quite short.

                          Are you certain the hall sensor is bad?

                          If the car starts and runs it must be working.

                          With the 3B it’s very important that the timing is spot on, you need to check this very carefully. Roll the car forward in gear till the flywheel Zero mark (0) lines up in the bell housing window then check the dizzy rotor is exactly on the mark.

                          Do you know if the plastic dizzy gear has been replaced with a metal one.
                          Last edited by newsh; 15 September 2020, 09:40.

                          S2 Coupe 3B Project


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                          • #14
                            If the dizzy timing is slightly out it can cause running issues at higher RPMs

                            Same is true if there is a lot of backlash in the dizzy drive caused by a worn gear or plastic gear about to self destruct! Lol

                            S2 Coupe 3B Project


                            Ur quattro restoration

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                            • #15
                              Nope havent opened it yet. Was thinking about changing it to the one 034motorsport has maybe while im at it.

                              Just gotten the g40 fault from vcds a few times.. Can it be something else maybe?

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