Lost on 98 TDI low power problem

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by 408cuda, Jul 3, 2010.

  1. 408cuda

    408cuda New Member

    Joined:
    Jul 3, 2010
    Messages:
    2
    Hi guys/gals. First post. Been using the how to section to diagnose (or try) the sudden loss of power on my 98 Beetle 5spd TDI with 125k. This site is amazing and incredibly helpful. I have about 1000-1500 miles on the beetle since buying it and it was great while it lasted, 42+mpg with no problems. One day it just didn't have the kick it had the day before, like the turbo wasn't working. Scanned for codes and got nothing. After finding this site I started by replacing the MAF from Advance auto, no diff. Next I cleaned a very clogged intake, EGR, and even VNT vanes. Thought I found it with a sticky VNT actuator so I bought a new Garret unit and all gaskets from tdiparts. Put it all back together and while it feels stronger it still doesn't feel like it did before. I unplugged the MAF before I did all this and it seemed to make a difference so I thought it was working. Now I unplug it and it seems to make no difference, and in fact I am getting codes ranging from 1144 to 1146 that come and go even after clearing and leaving MAF hooked up. I had it running rough at one point and found it was popping #34 fuses setting off a handful of codes. I wiggled the 109 relay and it seemed to stop that? Anyway, it's still not right with the CEL on for 1145/MAF at the moment. I don't have a VAG-Ross scanner or know anyone with one. Any ideas on what it might be? I plan to switch EGR/TURBO solenoids and check more for leaks but the MAF codes have me wondering. I measured the voltage of the MAF wires hooked up and if memory serves it was pin 2-bat voltage, 3-nothing/grnd, 4 5.0 volts and 5 had about 11 volts. Any advice it greatly appreciated, I miss my TDI and want it back! Thanks.

    Forgot to mention:
    I also replaced the fuel filter
    The engine idles and runs great just suddenly down on power
    And the engine temp light is almost always lit up blue, it rarely and briefly goes out.
    Last edited by a moderator: Jul 4, 2010
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  2. Two Mikes

    Two Mikes New Member

    Joined:
    Jul 3, 2008
    Messages:
    85
    Maybe the coolant temperature sensor is bad? It was a common problem on the newer cars. I would get the vag com before throwing more parts at it though. The way I understand it, if your MAF is unplugged and there's no difference it's bad.
  3. ZoomALH

    ZoomALH New Member

    Joined:
    Jun 19, 2009
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    85
    When was the timing belt last done? You double checked all the vacuum lines right? Everything was put back after the intake job and the EGR works?
  4. 408cuda

    408cuda New Member

    Joined:
    Jul 3, 2010
    Messages:
    2
    I bench tested the EGR and it worked. I checked most of the vac lines but not sure how to test the whole system. The line to from boost sol to actuator is good as well as the EGR. Not sure when/if the belt was done, got no service history with the car. It ran great one day, then down on pwr the next like flipping a switch. I still get p1145 mass air shorted to b+. The connector on my MAF is somewhat broken up and I found there was nothing separating the wires internally and it was indeed shorting to the ground (pin 2 touching 3 IIRC) so I took the wire separator from a 98 Beetle gas I have and know the wires are not touching but I still the same problem. In fact now all the pins on the MAF show BAT volts when its running. I don't what would cause that, new sensor got shorted as well or ECU? Thanks.
  5. Seatman

    Seatman Active Member

    Joined:
    Jul 9, 2010
    Messages:
    5,246
    Car:
    2000 Mk4 Golf Estate 1.9tdi 174 bhp
    Location:
    Scotland
    Mods:
    PP764's, turbo and mapping
    loss of power

    Hi, I don't know if this helps, but on my 2000 seat cordoba 1.9tdi the ecu is in a rubbish position. It sits below the windscreen and gets dripped on a lot when it's raining. When I first got the car I started experiencing quite a few problems i.e. the car would lose power, wouldn't restart e.t.c. I took the ecu out and opened the casing and the contacts were all covered in corrosion, wet and shorting out. I cleaned the contacts carefully with a small screwdriver an cloth and cleaned the casing, dried it thoroughly and waterproofed it with silicone and the car has been great ever since. Hope this is helpful

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