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Thread: Weak acceleration

  1. #1
    Join Date
    Feb 2005
    Location
    Grand Marias USA
    Posts
    155

    Default Weak acceleration

    1989 525I with 173800 mi is slow to accelerate from a standing start and has little power climbing up hill. I noticed the other day that in really cold weather wayyyyyy below freezing!!!!!!! the idle is fluctuating right after starting, but I have no idle problems if the car sits in a heated garage overnight. I recently had the car shipped to Minnesota after not being driven for almost 7 months. Any ideas on where to start would be helpful.
    Jim

  2. #2
    Join Date
    Mar 2007
    Location
    Liverpool UK
    Posts
    1,536

    Default

    Quote Originally Posted by guinness View Post
    1989 525I with 173800 mi is slow to accelerate from a standing start and has little power climbing up hill. I noticed the other day that in really cold weather wayyyyyy below freezing!!!!!!! the idle is fluctuating right after starting, but I have no idle problems if the car sits in a heated garage overnight. I recently had the car shipped to Minnesota after not being driven for almost 7 months. Any ideas on where to start would be helpful.
    Jim
    You could give changing the fuel filter a go as it may be causing weak fuel flow hence poor acceleration... I changed mine to find it was 13 yrs old! Check the air filter too if it hasn't been changed in a LONG time it may be causing an issue. And check for air intake leaks for the idle - often they will be worse in the cold and improve as the car heats up as it seals any tiny gaps etc.

    HTH!
    1995 XJR: 4.0L S/charged straight 6 Auto

    What... It's not broken??? I can still fix it

  3. #3
    Join Date
    Feb 2005
    Location
    Grand Marias USA
    Posts
    155

    Default

    Doing the fuel filter this weekend and the air filter is new. Thanks for the air intake idea, I hadn't thought of that.
    Jim

  4. #4
    Join Date
    Nov 2006
    Location
    Germany
    Posts
    475

    Default

    Quote Originally Posted by guinness View Post
    Doing the fuel filter this weekend and the air filter is new. Thanks for the air intake idea, I hadn't thought of that.
    Jim
    If things are good to go with the filters, I wonder how the injector spray patterns are...you say it starts and runs fine other than some wobble in the idle, right?

    I hesitate to offer crappy spray patterns due to dirt as a possible cause of your low power situation as you didn't state a hard start when cold complaint.

    It would be pretty weird to have the car start O.K. when cold but have such crap spray patterns that the gas can't vaporize at higher flow rates (and tons of COLD air coming in). Could an injector spray O.K. at low flow rates yet go to total crap at 80-100% flow? I think I remember seeing some 'manual' injectors act like this in the late 80's but I could be making that memory up...gotta love getting older!

    Yet I am left with the vision the other poster suggested, low max fuel flow rate causing a lean condition under high power demands...fuel system cleaner is cheap!

    Brian

  5. #5
    Join Date
    Feb 2007
    Posts
    618

    Default

    is it an auto? torque converter? Or is it like this all the way through the rev range?
    UK 1997 e34 540iA Touring, 1989 535i Sport - now sold, 1998 Mercedes CLK 200 Coupe


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