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Thread: Misfire and random boost?

  
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    Misfire and random boost?

    My car has developed a new problem. Some times when passes about 3,000rpm it hesitates as if it has cut out and bump started itself again and does it a few times until it gets higher up the revs. When it does it no dash lights come on and the boost dropps completely but you can hear the turbo is still spinning. The EML is on but with the same old fault codes due to the lack of an ABS pump. Ive changed the plugs and as far as I can see there are no boost leaks and there is nothing in the way of the actuator. Any ideas?
    It would definitely go better with an engine in it

    ZLET converted SXi See Here

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    how long does this hesitation last? i was getting the same symptoms at 3k and again around 4.5k. in 5th at top speed it was a pig to drive.

    bought new coil pack and plugs and it ran sweet as a nut, symptoms very close to yours

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    Quote Originally Posted by gsi_10 View Post
    how long does this hesitation last? i was getting the same symptoms at 3k and again around 4.5k. in 5th at top speed it was a pig to drive.

    bought new coil pack and plugs and it ran sweet as a nut, symptoms very close to yours
    lasts about the same as that tbh. Ive had a coilpack fault and changed it. It was similar but not the same with that. When the coilpack was gone it did it all the time, this only happens sometimes
    It would definitely go better with an engine in it

    ZLET converted SXi See Here

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    My pack was away and it did it sometimes, not always.

    If cold it would pull fine, soon as it warmed up it was like a nudge in the back at around 3k, a slight misfire. Sometimes it would go great but under full load it would kill boost etc, lasted like a quarter of a second, but really pissed me off. took a blast round a backroad when it pissed me off once too many to throw up the eml. P0300 P0303 codes. new pack sorted it and pulls great now.

    So advice would be take it right up the rev range in 3rd, mine flashed up the eml and chucked it into limp mode. Was a godsend as before i had been babying the car and had no codes to work with. Worth a shot mate

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    Quote Originally Posted by gsi_10 View Post
    My pack was away and it did it sometimes, not always.

    If cold it would pull fine, soon as it warmed up it was like a nudge in the back at around 3k, a slight misfire. Sometimes it would go great but under full load it would kill boost etc, lasted like a quarter of a second, but really pissed me off. took a blast round a backroad when it pissed me off once too many to throw up the eml. P0300 P0303 codes. new pack sorted it and pulls great now.

    So advice would be take it right up the rev range in 3rd, mine flashed up the eml and chucked it into limp mode. Was a godsend as before i had been babying the car and had no codes to work with. Worth a shot mate
    Thats what it did when the coil pack was gone but it was replaced with a genuine one which has only been on the car for 4 months. Its not the same sort of misfire, its asif the car is cutting out then bumping again. Its been up and down the revs in all the gears and there are no codes. Im pretty much sure its not the coilpack this time.
    It would definitely go better with an engine in it

    ZLET converted SXi See Here

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    maybe a bcs?

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    found out what the problem was. I opened the bonnet with the car running and started checking plugs cos I thought it might have been the lambda sensor not plugged in properly. When I checked it I caught the wire for the sensor that sits in the pipe after the intercooler and the car cut out. Turns out the wire had been rubbing on the battery tray and worn through and as I was boosting and the pipe was swelling and moving it was causing the wire to short on the metal under the tray and making the car cut out. That was where the juddering came from when the car started to boost. Sure enough, a new bit of wire spliced and soldered in and some of that plastic tube round the wire the problem has gone and the cause removed. Happy days.
    It would definitely go better with an engine in it

    ZLET converted SXi See Here

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