Bora 4motion won't accelerate.

Discussion in 'Mk4' started by sports racer, Jul 24, 2018.

  1. sports racer Forum Member

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    I'm picking up a Bora V6 4motion next week for a really good price because it's got a problem no-one seems to know how to fix. It has no power. Idles nice and sounds sweet when you rev it in neutral but start to drive off and the accelerator pedal may as well be disconnected for all the good it does. It does accelerate but very slowly.

    The local auto electrician plugged it into his scanner which said the oxygen sensor was faulty and killed the ECU. How they came to that conclusion I don't know - how can a signal from a sensor damage a ECU??? Anyway, both were replaced and didn't fix the problem.

    On a short test drive I disconnected the MAF but it made no difference, didn't even make it worse. I didn't check to see if the limp home light was on but there wasn't any buzzer sound.

    I'll know more when I get the car home but what should I start looking for?
     
  2. KeithMac Forum Junkie

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    First thing I'd do is a fuel pressure test with a proper gauge, normally 43psi or there abouts.

    Test it at idle and under load (if you can safely?).
     
  3. GVK

    GVK Paid Member Paid Member

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    Could be anything.
     
  4. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Scanner is VCDS?
     
  5. sports racer Forum Member

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    Picked it up yesterday. When I drove it to my brothers about 5 ks away it was slow but kept up with the traffic (just). I got to 200 metres from his place and it lost all power, wouldn't rev at all past idle. I bunny hopped the last 200 metres and parked it for the night. Today I went back with a new fuel filter and it's heaps better. The old filter was so blocked I couldn't blow through it, no wonder it ran so bad. Glad it was the previous owner and not me who spent heaps on troubleshooting by the "experts" and replacing parts that they said were faulty. :thumbd:

    I spent a whole $23 for the filter and it's much better. There's power below 2500 rpm but not much above that so I drove the 100 ks home in 6th all the way. By the time I got home the powerband was up to 2700. At this rate it should be ok by Christmas.

    How long does it take for the computer to reset itself now that it has proper fuel pressure? Should I disconnect the battery to help it reset?

    Cheers

    Paul

    [​IMG]
     
    Last edited: Jul 27, 2018
  6. sports racer Forum Member

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    I scanned it and get the following 4 fault codes 1) P1630 2) P3211 3) P3212 4) P1426 and 1 pending code - P0102.

    Are these descriptions correct and how do I fix them?

    P1630 - Accelerator pedal position sensor low input
    P3211 - Oxygen (Lambda) sensor B1 S1 Heater return coupling
    P3212 - Crankshaft position sensor A circuit low input
    P1426 - Tank ventilation valve open circuit
    P0102 - MAF sensor circuit low voltage

    Some more info. When I disconnect the MAF sensor it makes no difference to the running of the engine - it doesn't idle differently or run rough.

    I took off the intake pipe to see what the throttle butterfly valve was doing. With the engine idling then pushing the pedal to the floor it opens all the way for a fraction of a second then closes so it's almost shut. If I keep the pedal to the floor it revs to 5200 and goes no further.

    With a bit of luck cleaning or replacing the accelerator sensor will give me the acceleration I'm missing. Then I'll see if the other faults come back when I scan it after that.

    Cheers

    Paul
     
    Last edited: Aug 4, 2018
  7. Tristan

    Tristan Paid Member Paid Member

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    I wonder did some of the gunk make its way to the injectors.. Low input might have been just a low battery.
     
  8. sports racer Forum Member

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    The battery is new and I do over 200 ks a day so there shouldn't be a problem charging it. I ran a bottle of injector cleaner through the tank and it's never coughed or spluttered. Pretty certain the problem is electrical.
     
  9. Tristan

    Tristan Paid Member Paid Member

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    I meant more so from before your ownership when the previous "experts" were trying to fix it.
     
  10. sports racer Forum Member

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    You might be on the right track. After more troubleshooting it's looking like the relay for the ECU isn't letting the full voltage through. I'll know more after I replace it.
     

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