Diagnosing Long Term Mass Airflow and Engine Issues (Turbo?)

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Makhaon, Apr 17, 2017.

  1. Makhaon

    Makhaon New Member

    Joined:
    Oct 21, 2016
    Messages:
    2
    Car:
    Volkswagen Golf TDI 2004
    Location:
    Morrison, CO
    Hi all;

    This is my first post, although I've gotten a ton of value from browsing these threads over the past few years. I'm running into an issue that is idiosyncratic enough that I thought I'd check and see if anyone here had ideas.

    2004 Golf TDI, BEW engine, 153K
    (Timing belt replaced at 87K)

    I've been getting the "mass airflow sensor" code for a long time now. I replaced the sensor, but it didn't solve the problem. I got it checked out and found that I needed a new camshaft; with the help of the walkthrough here, I did that myself with a KermaTDI camshaft replacement. Everything went well and the car seemed to be running better than before, but I've now noticed some other issues--and it's still throwing the same mass airflow code! Here are the symptoms:

    slow oil leak - This seems to be from the valve cover gasket, so perhaps I installed that incorrectly when replacing the cam.
    increased engine noise - not at first, but when the car has been going for a while and/or at high speeds, I can hear a louder sound from the engine. It reminds me of a jet engine warming up or cooling down, actually. It's especially noticeable when I'm slowing down coming off the highway. I also recently noticed that that sort of whirring noise increases and speeds up as the car speeds, up, not just when the engine is going faster--I heard it while speeding up in neutral going down a hill.
    extra black smoke from the exhaust - especially when accelerating, but mostly at higher speeds (40-60 mph)

    Gas mileage is holding steady, although occasionally it seems like the power is diminished.

    Could all of this be from a valve cover problem? I'm also suspicious of the turbo starting to go bad. What does this all sound like to folks here?

    Thanks for your time!
     
  2. Ed Ke6bnl

    Ed Ke6bnl New Member

    Joined:
    Aug 25, 2015
    Messages:
    19
    Car:
    2002 VW Jetta TDI
    Location:
    So. Ca.
    Mods:
    none
    Let me just guess some attention is need to check the turbo. BUT I am a new owner if a 2002 tdi. Definitely lets hear from some experts, plenty out there.
     
  3. Seatman

    Seatman Well-Known Member

    Joined:
    Jul 9, 2010
    Messages:
    5,795
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    The oil leak is fairly common with the PD engine, most including ,myself take the cover off, clean it al up then use a smear of oil resistant sealant, sorts that right out.

    For the maf it's worth removing the battery and battery tray and cleaning up the earth points down there, there's at least 3 with quite a few wires. Check for any that look damaged but mostly just make sure it's all clean as that can cause maf issues.

    It sounds like the whirring is maybe a wheel bearing, jack up each front wheel, spin the wheel while holding the spring, if you feel roughness through the spring the bearing is worn, should be nice and smooth.
     
  4. Makhaon

    Makhaon New Member

    Joined:
    Oct 21, 2016
    Messages:
    2
    Car:
    Volkswagen Golf TDI 2004
    Location:
    Morrison, CO
    Seatman, all of those recommendations are great! The wheel bearing diagnosis makes a lot of sense, I've been having some uneven tire wear. And great tip on checking underneath the battery.

    As far as re-sealing the gasket, are the valve cover bolts re-usable in your experience?
     
  5. Seatman

    Seatman Well-Known Member

    Joined:
    Jul 9, 2010
    Messages:
    5,795
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    Yeh, they're fine to reuse, never heard of anyone replacing them to be honest.
     
  6. crsmp5

    crsmp5 Well-Known Member

    Joined:
    Feb 14, 2012
    Messages:
    1,498
    Car:
    85 kubvan
    with a jack under the control arm... cannot let the wheel hang down, it will load the cv joints if you do.. and give false positive... hell right side axle of a mk4 hits the subframe at full droop :p

    step 2... start car up... put in 4th gear (no throttle needed.. just idle).. with a long stick/screw driver/crowbar.. place it on the strut housing of the spinning wheel... put your ear up to it and give it a listen.. works great... compair sides of car.. if one louder.. its bad.. but long stick of any kind that your safe distance from spinning wheel.. traction control must be off... does not work on 4wd/quattro/syncro/4motion cars.. the system dislikes this and makes all kinds of bad sounds
     
    Last edited: Apr 19, 2017
  7. Seatman

    Seatman Well-Known Member

    Joined:
    Jul 9, 2010
    Messages:
    5,795
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    It can hang down fine bud, no false reading. Grab hold of the spring with one hand and spin the wheel with the other. You can't feel a rattly shaft through the spring, just a bad bearing.
     

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