- Engine misfire
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    Thread: Engine misfire

    1. 07-30-2019 12:28 PM #1
      I have a 1.8L Jetta engine 1986 in a 79 Westfalia. This thing is a rocket and fuel comsumption is way better than the original, and also I could cruise at 120 km/h or 75mph which is impossible with the original engine. It could do that... when it works!

      It’s been 2 years that I try to resolve an issue.
      At first, we got misfires during uphills but it wasn’t too bad. From last year, I noticed that when the engine is hot and the outside temperature is hot as well it would do it in uphill and also sometimes on a flat surface.
      But this year, it is strange, on hot days it is horrible even on a flat surface, but after 30 minutes driving. It’s as if the engine would like to stall for a split second and then is alive again, no back fires. And this year it does this when the engine is cold at low RPM before hitting the highway.
      I even had to stop for 30 minutes when we reached the peak of a mountain in Vermont as I could not pass 60 km/h or 35 mph, it did not have any more power.

      It has been sent to 2 garages for the last 2 years.
      What has been changed:
      - Fuel pressure regulator
      - distributor
      - knock sensor
      - ignition coil
      - fuel filter (fuel was draining very well from the tank so no blockage up there)
      And air filter cleaned (K&N nose cone)

      I am completely lost, as I do not know where to search now. Wife is hating the Westfalia 😂
      The fuel pump doesn’t do any freaking noise, and I hear it well before starting the engine.
      Could it be a fuel injector problem or an ECU problem?

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    3. 07-30-2019 04:05 PM #2
      I think what you need is a running fuel pressure test.

    4. Member
      Join Date
      Aug 23rd, 2011
      1979 Mk1 Scirocco
      08-21-2019 02:11 PM #3
      I assume you have CIS
      Sounds like you are having fuel pressure issues causing lean conditions. Check that your timing is correct too as this could make a poorly tuned system worse.

      Check the WUR is working correctly, that is done in a fuel system check procedure.
      Then check that the air fuel adjustment is correct.
      You will need the chiltons manual and a way to read your co readings from the tail pipe. if you have a narrow band O2 sensor (CISE?), you can read it with a voltmeter to see if you are close at idle.

      Harbor freight sells a master fuel pressure kit that has the correct fittings.
      If not a old VW shop that understands CIS should be able to check system pressures for you.

      Did you check any of this when the engine swap was done?
      The system should have been tuned to the bigger motor.

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    6. 08-21-2019 11:32 PM #4
      something loose in the tank?

    7. 08-28-2019 12:08 PM #5
      Look at this site and see if it applies to your transplanted engine. It worked for my '89 cabriolet 1.8L.

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