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Thread: Rough Running After Replacing Timing Chain Sensor

  1. #1
    Join Date
    Jan 2015
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    Bluffton, South Carolina
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    27
    My Cars
    1997 BMW 840 CI

    Rough Running After Replacing Timing Chain Sensor

    I cannot get the cap off the diagnostic connector. I did a few things this weekend. Replaced Vapor Canister, Timing Chain Tensioner and the Timing Chain Sensor. Now the car is running rough and has no power under acceleration - it barely moves when depressing the accelerator. Do I have a faulty timing chain sensor?
    Last edited by Jolo3361; 07-30-2018 at 10:08 AM.

  2. #2
    Join Date
    Jan 2004
    Location
    Toronto, Canada
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    1,330
    My Cars
    BMW 850CSi
    The diagnostic cover comes off by twisting counter-clockwise 1/4 turn then slides straight up.

    Sounds like you’re in LHM (running on 6 cylinders). Perhaps you forgot to reconnect something (MAF, etc)


    Sent from my iPhone using Tapatalk

  3. #3
    Join Date
    Sep 2011
    Location
    Vancouver Canada
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    419
    My Cars
    '91 850i, E39 & E46 Cars
    Dr.T - note that Jolo has a 1997 840- V8 E31, not an 850 V12, so not running on just 6 cylinders. Could be that the MAF connection is not secure, though.
    /Henry

  4. #4
    Join Date
    Jan 2015
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    Bluffton, South Carolina
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    1997 BMW 840 CI
    Thanks much. I'll check the MAF. I had the diagnostic cap off last month to diagnose my Timing Chain Sensor and the O2 Sensors, but for some reason, the entire unit is twisting with the wires below which are already fragile. I will have to play with it some more. The car ran great after replacing the O2 sensors so it has to be the MAF. I believe the vapor canister pipe vents down and is not connected to any hose. Is that correct?

    Thanks again for the quick and helpful responses.

    Kind regards
    Joe

  5. #5
    Join Date
    Jan 2015
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    Bluffton, South Carolina
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    My Cars
    1997 BMW 840 CI
    Thanks you were correct. I was twisting from the top of the cap rather than the knurled ring below the cap. 1/4 counter turn did the trick. No fault codes. I will recheck all my connections this evening Thanks again

  6. #6
    Join Date
    Jan 2015
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    Bluffton, South Carolina
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    27
    My Cars
    1997 BMW 840 CI
    Its a vacuum leak. I took the air induction off and noticed the center nipple on a t fitting by the dip stick has no hose attached . Cannot find the missing hose, but once I do, problem solved. Any ideas what hose connects to it. Tomorrow Ill put the car on the lift and see if I can find it.

  7. #7
    Join Date
    Feb 2010
    Location
    Hampshire UK
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    My Cars
    99 840ci Sport Indv
    It doesn't attach to anything on any country variant except for the German one - where the centre spur connects to a disturbance valve that is used for their 'smog' test to introduce air.

    Your one should have a cap fitted - more information here:

    https://www.meeknet.co.uk/e31/E31_84..._Tick-Over.htm
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


    My BMW Repair YouTube Channel
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  8. #8
    Join Date
    Jan 2015
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    Bluffton, South Carolina
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    1997 BMW 840 CI
    That's it Timm. I must have knocked it off when I dissembled the air intake. I found under the car a small piece of hardened rubber that looks to be part part of a plug. Thanks Timm, you saved me a lot of time and grief . And thanks to Henryc and Dr.T, very much appreciated.

  9. #9
    Join Date
    Feb 2010
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    99 840ci Sport Indv
    If that one has failed you can be the other three have! Two on the PCV and one under the throttle body......
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


    My BMW Repair YouTube Channel
    My Current 840ci Sport Individual
    My Current 650ci Sport Individual
    My E31 Repair and Information Website
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    My E63/E64 Repair and Information Website

    Chase - Heroes to a generation

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