03 Jetta TDI manual transmission cruise control problem

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by Aaron T, Mar 14, 2017.

  1. Aaron T

    Aaron T New Member

    Joined:
    Mar 13, 2017
    Messages:
    3
    Car:
    2003 Volkswagen Jetta TDI
    Location:
    Kensett Iowa
    I just bought 2003 Jetta TDI with a manual transmission and have noticed some cruise control problems. Driving down the highway at 60 mph (and even up to 70 mph) the cruise sets and maintains speed with no problem. Anything faster than 60 mph the accelerate button does not work. If the speed is set at 55 the accelerate button will accelerate the car to 60 but after that nothing happens. The cancel button works fine, pushing the clutch in or tapping the break pedal cancels the set speed as it should. If the speed is set to 55 mph, canceled, and the resume button is pushed it will resume to 55. Driving down the highway everything seems normal however when you go down the interstate at 75 mph or 80, when setting the cruise control, it will gradually slow down and does not maintain the speed set (even on a flat road). The accelerate button does nothing when pushed. Cancel button pushed, clutched pushed in, or break pedal pushed, all cancel the set speed as they should. By the way these buttons are on the steering wheel on this car. There is no CEL on. The break lights work too.

    Has anyone else come across this problem? What do you think? Road trips down the interstate are going to be miserable if not fixed. :-/

    Thank you!
     
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  2. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    23,804
    Car:
    2006 Jetta TDI
    Location:
    CT
    Are you sure that it's not in low power mode? Does the car feel as slow as a slug? Can you accelerate briskly at 70 mph? You should be able to.

    If yes, this is very weird...
     
  3. Aaron T

    Aaron T New Member

    Joined:
    Mar 13, 2017
    Messages:
    3
    Car:
    2003 Volkswagen Jetta TDI
    Location:
    Kensett Iowa
    Chittychittybangbang, that might be a possibility. It doesn't seem like I can accelerate briskly at 70 mph. I did get it up to 90 one time but not briskly. The speedometer seems like it might be running 5 mph too fast. This was comparing it to a speedometer app on my phone so I don't know how accurate that is. What do I need to do if it is in low power mode? Is low power mode the same thing as limp mode?
     
    Last edited: Mar 14, 2017
  4. Seatman

    Seatman Well-Known Member

    Joined:
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    5,762
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    No, limp mode is a sudden loss of power that returns with a cycle of the key, yours sounds like permanent low power.

    Check the diy pages for more info, possibly bad maf etc
     
  5. Aaron T

    Aaron T New Member

    Joined:
    Mar 13, 2017
    Messages:
    3
    Car:
    2003 Volkswagen Jetta TDI
    Location:
    Kensett Iowa
    Thanks Seatman. Right after my reply I found the limp mode and low power mode threads. I definitely have a low power problem. I just took it for a test drive and had it floored in 5th gear and it was slooooowly getting up to 80 mph. The RPMs were hovering around 3000 at that speed. I think it might be a dirty EGR and intake manifold. I took a peek in the EGR and it was pretty nasty in there. I'll start working through the low power thread and get those points checked off.
     
  6. Seatman

    Seatman Well-Known Member

    Joined:
    Jul 9, 2010
    Messages:
    5,762
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    You could also unplug the maf and try it, it should be better or worse but not the same, if it is the same you may want to find someone with vagcom and log it. A bad maf rarely throws a code unless it's an electrical fault.
     
  7. chittychittybangbang

    chittychittybangbang Administrator

    Joined:
    May 23, 2007
    Messages:
    23,804
    Car:
    2006 Jetta TDI
    Location:
    CT
    Yeah, you should have no problem accelerating past 100 mph if you floor it. You have permanent low power which causes the cruise to slowly slow down to where the engine can maintain power.
     

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