VWVortex.com - Engine bogging down under load - Digifant 2
Username or Email Address
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    VWVortex


    Page 2 of 2 FirstFirst 12
    Results 26 to 33 of 33

    Thread: Engine bogging down under load - Digifant 2

    1. Member rix337's Avatar
      Join Date
      Feb 11th, 2003
      Location
      Powder Springs, GA
      Posts
      4,792
      Vehicles
      93 Cabby, 17 Jetta SE, 17 GTI Sport, 93 Corrado SLC(sold)😭
      03-26-2020 07:04 PM #26
      Quote Originally Posted by matty kirk View Post


      As a side note, and completely unrelated I tried using the valve guide removal method pictured on a Ford 300 6 that I am rebuilding, not realizing that the guides are cast into the head in many cases. DAMN! Oh well, turns out that wasn't the head I wanted to use anyway. Live and learn.
      Ouch! Glad it wasn’t the head you wanted. That would have been an expensive way to find out you can’t remove them, lol. We all have the popcorn ready waiting to hear what is found. Thanks for keeping us up to date.
      Tuco, there are two kinds of people in this world...the ones with loaded guns, and the ones who dig. You dig. - Eastwood

      93 Cabby 09 Jetta TDI 93 Corrado S/C(sold) 17 GTI Sport

    2. Remove Advertisements

      Advertisements
       

    3. 03-26-2020 10:57 PM #27
      It has been a while for me and this FI system.
      Things that I saw that commonly created running issues:
      1. Coolant Temperature Sensor
      2. Fuel Pressure Regulator (leaks gas into the vacuum hose)
      3. Broken/loose ground wires on the intake manifold (very common)
      4. Incorrect Igntion Timing (adjusted with the CTS unplugged and after you rev the warm engine up a couple of times I think)
      5. Faulty Air Flow Sensor that can be adjusted a little
      6. Faulty Oxygen Sensor
      7. Clogged Catalytic Converter (although I haven't seen this on these cars, it is possible)

      I have had to troubleshoot many of these cars using the digital volt ohm meter at the ECM/ECU plug to find out why they were not running well and not passing emissions.

      Good Luck!

    4. 03-27-2020 08:47 AM #28
      My '90 Cabriolet suffered issues with the ignition coil. It exhibited the same issue you're having, hesitation and stalling upon hitting the throttle. I originally went through the same troubleshooting. It was far worse when the weather was hot, but once it started giving me trouble, it would continue through all weather conditions as if the hot weather killed it.

      ...just a thought.

    5. 03-27-2020 09:01 AM #29
      Quote Originally Posted by tolusina View Post
      Voltage on the ECU line to the O² sensor with the sensor disconnected is 0.45 VDC to 0.5 VDC, let's call this vRef as in 'reference voltage'. This may not be technically accurate nomenclature but it's helpful for us to work in these terms.
      It's called, 'bias voltage'.

    6. Member matty kirk's Avatar
      Join Date
      Jul 2nd, 2007
      Location
      Eugene, OR, transplanted from Eastern PA
      Posts
      1,001
      Vehicles
      1990 VW Cabriolet 1.8L 2H head/2L ABA block,02J 5sped,Digi2- 1981 Ford E-150, 300 6, 4 on the floor
      03-28-2020 04:42 PM #30
      OK. So.

      1st. Replaced fuel filter.
      Filter looked older than I remembered as I though I had replaced it back in 2014, or so, anyway, that;s still a while ago...
      At any rate, fuel sample from filter was mostly clean with only minor sediment present. Not enough that you expect to be detrimental to performance.

      2nd. 02 Sensor testing.

      With 02 sensor unplugged, I verified that vRef is in fact .51 volts.
      I then ran engine up to temp. Plugged in 02 sensor, and back probed ECU lead. With engine running voltage did in fact fluctuate from .01 to .09 volts rather quickly.
      When I revved the engine by hand voltage went high .09 and then resumed fluctuating as before.

      When I grounded ECU lead to battery, voltage went to 0.0 and remained there. Engine did not want to rev at all while ECU was grounded.

      When I used a AA battery between battery negative and ECU lead, voltage went high 1.38, but did resume fluctuating with throttle open.

      Not sure what exactly I found out here. But those are the results.

      The next thing I did was pull the 02 sensor and bench test it with a torch.
      Every test I watched online showed the 02 sensor generating upwards of 1.0 volt when heated with a torch.
      My 02 sensor would not generate over .07 volts at any time when heated with a torch.
      Last edited by matty kirk; Yesterday at 04:33 PM.
      Even a blind squirrel finds a nut in the dark, sometimes.

    7. Member matty kirk's Avatar
      Join Date
      Jul 2nd, 2007
      Location
      Eugene, OR, transplanted from Eastern PA
      Posts
      1,001
      Vehicles
      1990 VW Cabriolet 1.8L 2H head/2L ABA block,02J 5sped,Digi2- 1981 Ford E-150, 300 6, 4 on the floor
      Yesterday 04:48 PM #31
      After posting above, I installed the new 02 sensor.

      I also cleaned and re-gapped my spark plugs.

      Today I test drove the car, and I can say that the problem seems to be solved.
      My route was approx. 28 miles long, and the car performed well throughout. I a few hard runs through the gears, and did not notice any of the previous bogging or hesitation.

      Thank, guys.
      Even a blind squirrel finds a nut in the dark, sometimes.

    8. Yesterday 07:31 PM #32
      Winner Winner Chicken Dinner.

      Glad to hear.

    9. Member rix337's Avatar
      Join Date
      Feb 11th, 2003
      Location
      Powder Springs, GA
      Posts
      4,792
      Vehicles
      93 Cabby, 17 Jetta SE, 17 GTI Sport, 93 Corrado SLC(sold)😭
      Today 12:10 PM #33
      Hot diggity, something mostly simple. Glad to hear it.
      Tuco, there are two kinds of people in this world...the ones with loaded guns, and the ones who dig. You dig. - Eastwood

      93 Cabby 09 Jetta TDI 93 Corrado S/C(sold) 17 GTI Sport

    Page 2 of 2 FirstFirst 12

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •  
    vwvortex.com is an independent Volkswagen enthusiast website owned and operated by VerticalScope Inc. Content on vwvortex.com is generated by its users. vwvortex.com is not in any way affiliated with Volkswagen AG.