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Thread: BMW 325 poor acceleration under 4000 revs

  1. #1
    Join Date
    Jun 2010
    Location
    Costa Rica
    Posts
    3
    My Cars
    1992 BMW e36 318i

    BMW 325 poor acceleration under 4000 revs

    Hi there, I have seen several posts all over the internet related this same problem

    I have a 94 325is, M50b25tu engine on it.

    The problem I am having is that if I accelerate lets say from 2000 revs in 2nd gear (as an example), the car accelerates but slowly until it reaches 4000 rpms, then its like something kicks in and boosts the car up to the redline

    I have replaced spark plugs, fuel filter, oil changed...

    I have read some guys that replacing the crank/cam shaft sensors fixed the problem, the weird thing is, idle is perfect, and the engine seems to be working really good overall, even light-moderate acceleration is ok.

    Any ideas what to check?

  2. #2
    Join Date
    Mar 2010
    Location
    NJ
    Posts
    4,404
    My Cars
    325iC
    Could be crank or cam, but your symptom is classic VANOS failure, have a read:

    http://www.beisansystems.com/

  3. #3
    Join Date
    Jun 2010
    Location
    Heber City, Utah
    Posts
    754
    My Cars
    1997 M3 2007 X3m & 328xi
    You need to do your vanos seals. Look up Beisan systems!

  4. #4
    Join Date
    Jun 2010
    Location
    Costa Rica
    Posts
    3
    My Cars
    1992 BMW e36 318i
    Thanks everyone!

    Problem fixed!!

    This weekend I unplug both sensors to clean them, and noticed the camshaft sensor was barely plugged, it was lose. After cleaning it, I plugged it as it should be and then tested the car...

    What a difference! I felt I swapped the engine! Now I can feel the low-mid range torque, now I dont need to push the gas all the way to feel it accelerate.

    so here is a FYI to all of you with similar problems

  5. #5
    Join Date
    May 2011
    Location
    San Diego
    Posts
    285
    My Cars
    03 Z4 / 12 X5
    Quote Originally Posted by wodcutr View Post
    You need to do your vanos seals. Look up Beisan systems!

    Beisan states that the vanos seals are worn out if the engine has more than 20k miles on it......is that a bit of a stretch? I thought they went about a 100k miles before the seal becomes an issue.


    Thoughts?

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