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Slow revving

Discussion in 'Z3 Roadster & Coupé' started by Romeo, Feb 24, 2014.

  1. Romeo

    Romeo Regular Member

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    New to the forum so apology if subject has already been discussed before...

    Bought a 2.0 Z3 recently and noticed that engine is a bit slow to rev, especially compared to my previous cars. Engine is running pretty well and without misfiring but I found it takes some time for the revs to go down before up-shifting, in other words the revs don't go up/down instantly like on my 3.0 Jag.

    I heard of hard or "sticky" accelerator pedal so not sure this is normal or this would somehow affect the revs.

    Sorry new to BMW engine...

    Any good advice welcome :drinks:
     
  2. FRANKIE

    FRANKIE Zorg Guru (V)
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    Romeo, I bought a '96 1.9 Z3 towards the end of last summer. For various reasons I won't go into now, I have yet to put it on the road. But I have always worked on my own cars and have a decent working knowledge of their operation. There are several members who have expert experience that might know the answer immediately. I can only relate to this problem from experience with working on other cars. I would first check the throttle cable to make sure its not hanging up anywhere. I then would check the ease at which the throttle plate moves in the throttle body. There is a spray that is made just for the throttle body and is called 'throttle body spray' that cleans and lubricates the throttle body. Some cars have an Idle Air Control Valve (IACV). These are attached to the throttle body and usually have an electrical connection and a connection from your coolant, the heat from which controls the opening for idle air. Usually when this goes bad, it only effects Idling causing it to lope. If this these aren't the problem, the MAF sensor and EGR valve could be faulty. Other members could better advise you regarding these. Frankie
     
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  3. Aceman

    Aceman Moderator
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    Hi Romeo,

    There is a common problem on Z3's where the throttle cable gets stiff over time but not sure if you will the cable or fly by wire version. The only other thing that springs to mind at the moment is a possible problem with the clutch pedal switch which alters the throttle response when the clutch is depressed so it cannot be over reved. Other than that it could be a problem with the throttle valve motor being sluggish.
     
  4. zedonist

    zedonist Guest

    Induction pipe work leak, unmetered air can keep the revs high, cheapest and easiest thing to look at first
     
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  5. GazHyde

    GazHyde The Gaz Monkey
    Staff Member Administrator Global Moderator British Zeds

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    This was the problem with my 2.0 when I first bought it...

    The MAF unit and airbox is just to the left of this picture
    bmw-z3-induction-hose-split.jpg
     
  6. Romeo

    Romeo Regular Member

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    Thanks you all for your comments, I think i'll replace the throttle cable first and see what happen.
    The induction pipe might be worth checking as well...
     
  7. Romeo

    Romeo Regular Member

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    Well I checked... the induction pipe is fine and throttle cable looks newish or not that knackered anyway. bit confused now.
    Drove the car again today, still bit slow revving down. Starts to think it's just me ?

    IMG-20140226-00615.jpg IMG-20140226-00619.jpg
     
  8. zedonist

    zedonist Guest

    have you put it on a diagnostic? if you've ruled out the simple, then it should record as a code in diagnostic
     
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  9. Romeo

    Romeo Regular Member

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    No just looked for the obvious, will see how it goes. Thanks
     
  10. Romeo

    Romeo Regular Member

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    Hi again
    Car still running rough I think... Now misfiring when starting car from cold every time usually a couple of shakes which almost stops the engine for a fraction of second, all that before the automatic choke stops then afterward engine runs ok... Weird.
    Sometimes especially on lower gears it feels like the engine don't want to rev over 2/3000 revs and struggle as if I was doing 7000 revs !
    It sounds strained basically and not smooth at all, could it be a coil or injector problem ?
    Will get the car checked I think

    Has anybody experienced this before ?
    Cheers
     
  11. zedonist

    zedonist Guest

    Cam sensor springs to mind, mine did this before going completely, get it on diagnosis it will identify the issue for sure
     
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  12. t-tony

    t-tony Zorg Expert (I)
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    Smells like cam sensor to me it's doing what mine did,albeit a 2.0 6 cyl.;)
     
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  13. Romeo

    Romeo Regular Member

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    Ok thanks so it sounds like a known fault with the 2.0 L engine then ?
    Will get that checked, hopefully my local garage will found the fault.
    Fed up being left behind at the light ! :) :meh:
     
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  14. Romeo

    Romeo Regular Member

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    Finally got the car plugged in and nothing came up which is good news. I think the flat spots encountered are caused by an air leak somewhere.The garage found an air leak but no idea from where ! Will have to get booked again for a full check.
    Just wondering why the air leak not showing when car plugged in.
    Any idea where to look at ?
     
  15. oldcarman

    oldcarman Zorg Guru (V)
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    I'd look at each hose individually. Just because that induction pipe looks good in the pic, undo it and look for small cracks in the bend and underneath. Do this with every hose that has to do with air induction. Make sure all connections are torqued properly. A very small air leak can create havoc with the motor and your mind. Go at it systematically and slowly. Only then will you have peace of mind and can move on to other things. I had a jeep 4.0l fuel injected that would run perfect one minute and go absolutely crazy the next. All it was were loose connections and small, almost invisible to see, cracks. Heat around those lines is their worst enemy. HTH. JIM
     
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  16. zedonist

    zedonist Guest

    Jim is right check each hose individually, take it off bend it in all directions, mind I bet Jim normally packs each one with snow, and watches where the melted water runs out!
     
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  17. oldcarman

    oldcarman Zorg Guru (V)
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    Yup! Throw snow on it and wait for the engine to smooth out or sputter to a stop. Either way, you've found your leak or at least one. On our day of summer a squirt bottle works in place of snow. You may find it's only one leak or a combo but check them all carefully. Once you're positive no leaks then get on with the expensive stuff.
     
  18. Romeo

    Romeo Regular Member

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    Thanks sounds like I 'll have some checking to do then.
    Once I got that sorted I have this rattle under the car to track down ! Fun the Z...
     
  19. t-tony

    t-tony Zorg Expert (I)
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    Where's the rattle? Front , middle or rear?;)
     
  20. Romeo

    Romeo Regular Member

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    there is a very annoying rattle under the front of the car... I think!
    It now got so bad I can hear it pretty much all the time in any type of roads. I had a after market bumper when I bought the car and I thought that was the cuprit but with new bumper it's still the same. :grumpy:
    almost sounds like a loose cable or something like that... Not sure.
    But found that it does the same as I turned the wheel when I pulled away from my drive at less than 5 mph last night, so it could be from the steering ?
     

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