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Thread: Back Pressure cause juddering?

  
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    Back Pressure cause juddering?

    Past few months, ever since i fit my catback system, ive been getting juddering, which is usually when going steady speeds or sitting in traffic/trailing round roundabouts, often around 2-3k revs.

    Ive tried new plugs, going to put some injector cleaner in, and ive been told it can be other things such a EGR or exhaust blowing causing false lamba readings etccccc.......

    But can the new backpressures from the exhaust be causing this? If so, what can i doo?
    Its annoying! Makes it look like i cant drive when it does it!

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    LiamD's Avatar
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    Could be the coilpack. Search for "pedal test" on here, follow the guide in one of the threads and post any fault codes you may get.
    Astra GSi 03 in Arden Blue

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    Just done the pedal test, the spannercar warning light thingy just came on and flashed, and stopped flashing when i took my feet off the pedals :S And no codes!
    Is my car not compatable with the pedal test or something?
    1.6 16v sxi 52 plate

    Oooops! Just realised how to "count" the codes
    done it again
    0136

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    The catback will have reduced back pressure, not increased it, and it is not going to cause juddering so far as I know.

    If the light flashes continuously then it means there are no codes stored.

    At a guess, EGR valve, it causes those exact symptoms, mine failed this way with no codes stored at all. I'd also be checking you didn't knock a lambda sensor or it's wiring when fitting the catback.

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    check your rear lambda sensor as advised

    P0136 referrs to this

    probs been knocked during fitting the exhaust

    personally i would remove the sensor and clean the tip in petrol (dangle it in a cup of petrol for 10mins or so, dry off then refit)

    why not disconnect the battery or better still the 2 plugs on the ECU whilst u do it, then once reconnected the codes will be cleared

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    I checked it after i fitted because i knew i had knocked it a bit, but it seemed fine, connection was in etc, but could this cause the car to be like this? Since the lamba sensor doesnt have the "authority" to affect the way the car runs?

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    It will cause those issues - the lamda's monitor the exhaust gasses before and after the cat and adjust the fuelling to keep things 'correct'. If one is faulty or not connected correctly, then the readings will be out and the car will not manage the fuelling correctly hence the juddering, revs issue etc.

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    Hmmm.. My car does exactly this, but only after i got a vxr turbo fitted... still does it to this day.
    Does it happen when your just cruising along and it judders like it is hesitating? lasts for about a second?

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    yeh thats it! like when you nearly stall, but not like its dieing in that way, just the same judder, usually as or after ive use the throttle

    happens alot in slow traffic going round roundabouts etcc

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    Yeah... Its starting to really piss me off lol. Mine only happens only when im cruising along and not increasing in speed.

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