Pulsing Passat Idle

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by stefan, Nov 11, 2017.

  1. stefan

    stefan New Member

    Joined:
    Jun 19, 2012
    Messages:
    3
    Car:
    2005 Passat TDI Wagon
    Hey guys,
    My 2005 Passat TDI starting having a little issue. Often, if in gear, but stopped, the engine rpm starts to pulse a bit. Maybe a little faster than once a second. Its not huge, but you can see the tach twitch, and definitley feel it.. If I put it in neutral, it stops, if I move, I no longer notice it. It happens in both drive and reverse.

    Things I have done recently include an injector purge, popped off EGR to have a look at the intake, looks fairly clean. Disconnected the MAF to see if it effected the idle, but no. Fuel filter is new. Scanned, no codes. BSM is updated too on this car.

    I had a funny pulsing issue when I first got my Malone tune, years ago. We logged some data, and found he has an EGR setting wrong, but it also caused a pulsing, so I was wondering if the EGR could be acting up. I was also thinking about what the effects of a failing tandem pump or lift pump would be... Short of that, wondering if it could be something bigger like a torque converter or something in the auto transmission.

    My phone won't catch the sound of the idle very well, but this guy's YouTube is darn close to what I'm seeing, just as a reference:



    Anyways, just curios if anyone had some ideas as to what else I could check or test.

    Much appreciated, thanks all!
     
  2. stefan

    stefan New Member

    Joined:
    Jun 19, 2012
    Messages:
    3
    Car:
    2005 Passat TDI Wagon
    Today, I checked vacuum lines near the tandem pump, near the n75, and to air box, and checked the check valve there, with a mityvac. Everything held vacuum. Also, vacuum pump seems to be pulling lots of vacuum when running. Also ran input tests on EGR and anti-shudder valve to make sure they moved freely, and they looked good.
     

Share This Page