1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Rpm surge after release of throttle - any ideas?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Scullies, Mar 14, 2013.

  1. Scullies
    Offline

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,371
    Likes Received:
    372
    [Mar 14, 2013]
    This afternoon, I fitted a used speed sensor of eBay as I crushed the original one while fitting the engine.
    I also replaced the vac lines to the fpr, and DV. The boost gauge is tee'd into the DV vac feed.

    After a test drive, I have an issue with the rpm. It carries on rising after I lift off the throttle for about 1000 rpm then slowly drops down.
    Seems I have invented No Lift Shift without touching the ecu lol

    There is a fault code
    17748 - Camshaft position sensor (G40) / engine speed sensor (G28)
    P1340 - 35-00 - incor. Correlation.

    Do I need to calibrate something with VCDS.

    I had no other faults with the damaged speed sensor when it was electrically disconnected, just a non working speedo and no signal from speed sensor.
    Last edited: Mar 15, 2013
    #1
  2. Scullies
    Offline

    Scullies Well-Known Member

    Joined:
    Feb 9, 2012
    Messages:
    1,371
    Likes Received:
    372
    [Mar 15, 2013]
    So this morning I checked the engine timing marks. Crank and cam marks are spot on. Also have 16 chain rollers between the camshaft markings.
    fitted a new camshaft sensor but still have the same problem with the rpm surging after throttle lift off.

    I will try disconnect the engine speed sensor when it's cool enough to stick my hand down there.
    The sensor is working as my speedo is operational again.


    Edit - for being stupid.

    so after some thinking about the speed sensor and how it would be picking up engine speed from the gearbox, I have realised my mistake.

    seems I have been confusing the engine speed sensor with the vehicle speed sensor.
    Engine speed sensor is the crankshaft sensor that picks up a signal from the trigger wheel. Vehicle speed sensor that I replaced is in the gearbox and sends signal to your speedo.

    think I will have a few beers then look at the car again, it might make more sense then lol
    Last edited: Mar 15, 2013
    #2

Share This Page