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Highway Hiccups

Discussion in 'T3 & T4 Tech Help Clinic' started by Kevinthesyncro, Aug 28, 2021.

  1. Kevinthesyncro

    Kevinthesyncro Member

    Messages:
    79
    Location:
    Western Australia
    Hi everyone,
    I need some help. A while ago my 89 syncro started with what GoWesty call the highway hiccups (an intermittent misfire) this was on the way home from a very long road trip in WA. Fortunately we only about 300 klms from home and annoying as it was got home safely! I then did the soldering diode thing on the wires entering the ‘intake air sensor’ this worked for a while then GoWesty brought out a wire filter to be spliced in place of the original wiring going to the intake air sensor! At last this fixed everything up and my syncro started running perfectly, then after a few months the same problem reoccurred just as bad as the very first time travelling home from the road trip, so I ordered a new intake air sensor from GoWesty and finally I thought the problem was fixed, except now very occasionally the same problem has began again and I honestly have no idea how to fix or fault find???…..any ideas guys????
    Other than this issue I love my syncro and have owned it for the last 10+ years.
    Please advise, I think there will be some of you who have had a similar experience and overcome the problem???
    Cheers all
    Kev
     
  2. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    There was a factory fix for this. 025 906 302 an extra harness put on the air flow sensor.

    After fitting I didn't have the problem again.

    upload_2021-8-28_19-22-21.jpeg
     
    Last edited: Aug 28, 2021
    Barry likes this.
  3. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    Here is some official VW documentation. In theory this could still be claimed if you had a good VW dealer. I did hear of someone successfully claiming on a 20 year old T3.
     

    Attached Files:

    Elsie 76, Syncro27 and Grantus like this.
  4. Kevinthesyncro

    Kevinthesyncro Member

    Messages:
    79
    Location:
    Western Australia
    Hi syncro,
    The filter I fitted from GoWesty is their own version of the part that you fitted and they stand by it???
    I really don’t know what to do???
    Cheers
     
  5. Maccas

    Maccas Active Member

    Messages:
    66
    Location:
    Gosford, NSW
    Here's the rider GoWesty states in its article on their "rebuilt" AFM:
    "Note: The running issue with your vehicle may not be the air flow meter! Installing a GoWesty rebuilt unit may not make your vehicle run better, and it might make it run worse if the culprit is something else."

    So the something else could very well be maintenance items not done at all, not done more recently or done wrong.
    To that end, years ago a syncro owner produced a maintenance check list ... as a basic guide for others after his experience with maintenance and fault finding on his syncro. It's been modified a little but essentially the same:


    VW T3 - Periodic Maintenance\Fault Avoidance
    A checklist of causes / fixes, not exhaustive nor in a particular
    order, to help resolve present and/or limit future unpredictable behavior:

    01. faulty or incorrect spec spark plugs & gap setting
    02. faulty or incorrect spec spark plug ignition leads (OEM copper core)
    03. faulty distributor cap (cracked etc) and worn distributor rotor
    04. remove / clean all sensor connections … CRITICAL
    05. remove / clean all ground connections … CRITICAL
    06. faulty O2 sensor
    07. faulty temp 2 sensor … CRITICAL
    08. faulty Hall sender … part of the distributor
    09. remove / clean ECU main connector.
    10. test sensor continuity to ECU .. open circuit wire/s in wiring loom
    11. faulty fuel regulator
    12. faulty fuel filter
    13. check fuel pressure
    14. check vacuum
    15. check timing
    16. carbon build up on valves
    17. faulty fuel pump relay
    18. faulty ECU power relay
    19. faulty coil & /or connections.
    20. Air Flow Meter … carbon track worn, move.
    21. Air Flow Meter ... add capacitor across pins 2 & 4.
    22. Air Flow Meter ... add earth wire to AFM metal case to ground.
    23. & a few other things I haven't thought of.

    I do agree the AFM, after 30 year ... needs some TLC, as I and others have already done with success.
    However, I'd certainly recommend items in the checklist be considered and actioned first, before the AFM issue.
     
    Dapom likes this.
  6. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    See if you can get hold of a second hand one. They come up for sale.

    If it happens again. Just stop and go and have a coffee. When you restart it should be OK for a while. That is "Vanagon syndrome". Be careful about some of the fixes you get told. There are a lot of myths out there.
     
  7. Wiz

    Wiz Well-Known Member

    Messages:
    462
    Location:
    Near Ballarat
    Are you suggesting Kev should pretend he's driving an EV?
    PR
     
    syncro likes this.
  8. Kevinthesyncro

    Kevinthesyncro Member

    Messages:
    79
    Location:
    Western Australia
    Guys, many thanks for the good advice, but the bus was recently fully serviced and this did not happen whilst at the mechanics because it was during the ‘honeymoon’ period when I fitted the GoWesty filter and the bus was running good. I will check all connections though and fit an earth wire as mentioned although I question why VW didn’t do this from the factory? and will definitely check the plug leads (I thought all leads were now silicone for improvement) ?????
    Cheers Kev
     
  9. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    Because it's not a design problem. All of the earths are adequate when in good condition.

    Silicone is just marketing. VW use copper core cables with resistor connectors. The originals last for many years. The only real fail point is the resistors which can be easily checked. Owners replace perfectly good leads with aftermarket rubbish which doesn't last. General mechanics are used to cars with carbon leads that need to be replaced often.
     
  10. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    No just about 20 minutes should do. And he can also stop close to a coffee shop and not have to walk 5kms.:D
     
    Last edited: Aug 29, 2021
  11. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    Another thing that could cause similar symptoms is a faulty hall sensor or maybe a coil (rare). They can cause problems due to heat and when they cool down again they work OK.
     
  12. Maccas

    Maccas Active Member

    Messages:
    66
    Location:
    Gosford, NSW
    I'd highly recommend instead as soon as possible, to seek out WA domiciled highly experienced syncro owners for mouth to mouth "show & tell" advice . Such advice would include them identifying known local reputable syncro/T3 services you should seek assistance from ... rather than relying on a "convenient" general mechanic with no proven T3 background.
     
  13. Kevinthesyncro

    Kevinthesyncro Member

    Messages:
    79
    Location:
    Western Australia
    Where would I source a genuine set of leads? Seems like everything is coming from the states nowadays?
    I used to visit an old German guy who was unbelievably thorough and each time I left with a list of to-do items that would bring the bus back to “as left the factory” then he retired so I found another mechanic who was almost as good, now he has retired and I have drive over 120+ klms to Perth (which I am planning to do) to get this all sorted!
    I love the syncro but often I wish I still had my T2.
    Cheers Kev
     
  14. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    Leads would be at the bottom of my list with this fault. They can be checked with a meter. What leads do you have?
     
  15. Kevinthesyncro

    Kevinthesyncro Member

    Messages:
    79
    Location:
    Western Australia
    Hi syncro
    The leads were changed about 2 years ago and I believe they are silicone. Where in Oz would I source a genuine set of leads? Something I did notice yesterday while driving, when driving at normal highway speeds and the engine very slightly feels like it’s missing, the oil warning light has a very dull flicker, not a full bright glow as on turning the ignition on, just a barely perceptible light flicker and it’s not even visible if the sun is from the drivers side.
     
  16. Barry

    Barry Well-Known Member

    Messages:
    5,995
    Location:
    Abbotsford NSW
    I would be getting that checked out
    Can you get an oil pressure reading done?
     
  17. syncro

    syncro Well-Known Member

    Messages:
    10,290
    Location:
    Southern Highlands
    If they are NGK leads they should be OK. Even cheap silicone/carbon leads should last more than 2 years. Buy from Australian VW specialists. Mick Motors, Tooleys etc.
     
  18. gazman

    gazman Well-Known Member

    Messages:
    1,909
    Location:
    Perth WA
    There are plenty of reasons why a car might develop an intermittent misfire - we can all offer educated guesses but the best option would be to take it to a good vw mechanic. Where in WA are you?
    I wonder if you have a bad ignition related electrical connection that is causing the dull oil light glow and simultaneously reducing power at the coil causing misfire?
     
    Barry likes this.
  19. Kevinthesyncro

    Kevinthesyncro Member

    Messages:
    79
    Location:
    Western Australia
    Funnily enough I was beginning to think down those lines only this morning, not what you have just suggested but something in the electrics to do with the printed circuit in the dash pod or bad coil connections???. I have replaced the ignition switch quite a while before all this started but that’s an easy fix and I have changed several over the years all fairly simple to do so I doubt if it’s the switch and I only have one key in the ignition not like a bunch of keys hanging there causing damage???
     
    syncro likes this.
  20. Syncro27

    Syncro27 Well-Known Member

    Messages:
    6,630
    Location:
    Terrigal, NSW Central Coast
    Try adding a nice big thick battery cable as a second earth from the block somewhere to the chassis.

    My syncro previously had an ER27 6cyl engine which would start fine but it would miss-fire after it got warm and would really struggle.

    I did some research on the interweb and a specialist fuel injection bloke said earthing the engine is a great and very cheap starting point regardless of what you think of your existing earths.

    He said, when the engine heats up, the resistance in the wiring increases around the engine and this can give the computer false readings making the engine play up and even stall.

    After adding a battery cable I had lying around in the garage - a total immediate fix. It was like I put a new engine in. It was using the old VW copper wire strip earth which seems to like building up resistance.

    Might be able to see the big thick blue cable in this photo which is my second earth on my current T3 2wd engine

    [​IMG]
     
    Last edited: Aug 30, 2021
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