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2000 1.0 12v won't accelerate under load

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  • [Corsa B 1993-2000] 2000 1.0 12v won't accelerate under load

    Hi everyone,


    My son has a 2000 Corsa B 1.0 12v with 50,000 miles that he's had for 2 years now. It's been no problem during that period and has been regularly serviced by a friend so has been well maintained.


    A couple of weeks ago it started to loose power and, sort of die/cough when under load over 3,500 rpm. We have changed the Mass Airflow Sensor and blanked off the EGR valve but nothing has improved. Our friend has spent several hours looking over it today and has not been able to make any progress. It's not throwing any codes at all so we have nothing else to go on.


    We're out of ideas now and I don't want to just keep chucking money at it if we're not really making any progress.


    Does anyone have any ideas? All suggestions gratefully received.


    Cheers


    Pete

  • #2
    Since we can't see the car can you say something about the basic service items - ie can we assume the plugs and filters are all good, including the fuel filter which is often ignored - even by professionals. You say your friend has been maintaining it - but we need to make sure it's nothing obvious before going further.

    Also - was the replacement AFM a genuine Bosch one? The aftermarket ones often cause more problems than they solve.

    When you say there are no codes can you tell us how that's been checked please. The 12v ECU doesn't always speak to generic code readers, I've had a few where the guy has sworn blind there are no codes recorded and the using Opcom I've found the relevant code in there.

    If there are no codes, the EML is working but doesn't come on when it loses power, and it's happening under load and at higher rpm, I'd check the fuel delivery system. The pump may be weak and/or there may be a partial blockage.

    The other thing is to check the voltage at the battery with the engine off (should be about 12.5v - 13.5v) and then with it running (should be around 14.5v) - just to make sure it's not a weak voltage issue.

    One other thought - if you used a generic reader - I've known the EGR cause a problem at higher rpm which lodges in the ECU and doesn't go until the codes have been cleared. It shouldn't happen in theory, but it does - so have you cleared the ECU of all codes even if none seemed to be present?
    1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

    Comment


    • #3
      Hi Taurus,


      Thanks for your response.


      yes - the car has been regularly serviced and all plugs and filters are good - changed only about 6 months ago. We actually replaced the fuel filter today incase that was the cause but it hasn't helped.


      Mass flow meter wasn't a Bosch item unfortunately. I'm not sure what make it was but it was sorted from Euro Car Parts. Is there any way of knowing whether it's not working correctly? I've read somewhere that, to see if it's the case of the problem, it can be unplugged to see if it improves matters. It'll run a bit rich but won't cause a problem. Is this correct and something we should try?


      I'm not sure what kit was used to check the codes - just that the local garage and the mechanic we know who both have code readers found no codes when they checked. I don't know whether they have tried to clear the codes even though none are showing.


      i did wonder about the pump but just don't know enough to figure out if it's misbehaving.


      I took ok it out today and, if you are gentle with the throttle, you can get it to rev out ok. If you, for example, get it to 3,000rpm in 2nd and stamp on the gas, it'll get to about 4,000 and then have a massive kangaroo session that'll last for maybe 5 seconds. If you keep it planted, it will often get past it and carry on round to 5,000 though it's still a bit lumpy.


      Does any of this help at all?


      Cheers


      Pete

      Comment


      • #4
        1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

        Comment


        • #5
          Hi Taurus. Thanks again for another really detailed response. This is really helpful stuff.

          My son has the car booked in on Weds at a garage where they will plug a laptop in and he'll take it for a run to replicate the kangeroo-mode stuff and, hopefully, this'll give us a clue as what is going on. I reckon we'll wait to see what transpires from that before doing anything else.

          Just a quick thought - could this be a coil pack problem or would that automatically throw an EML code?

          Oh - and we're in Medway Kent, by the way!

          Cheers

          Pete

          Comment


          • #6
            It could be a coilpack breaking down, but the only way to tell is to try a replacement. They tend to fail as they get hotter. Sometimes it will throw a code - usually a Lambda code due to the exhaust gases being out of parameter if there's a misfire. But the coilpack itself won't throw a code.
            1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

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            • #7
              Thanks for all the help Taurus - turns out the misfiring was due to the cheap MAF - when the original (still faulty) Bosch part was put back on the car lost these new problems.

              Fitted a new Bosch part and the car is running wonderfully again. Goes to show - always get a proper part, especially if its a sensor!

              Many Thanks,

              Matt

              Comment


              • #8
                Glad it's sorted. At least it was an easy, if not particularly cheap, fix.
                1972 Viva restoration thread - http://www.thecorsa.co.uk/projects-b....html#post1534

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