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Thread: Big flat spot at low RPM?

  1. #1
    Join Date
    Nov 2004
    Location
    Gateshead,UK
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    926

    Default Big flat spot at low RPM?

    Hi all! I let my Father in law drive my E34 today. He was complaining about a big "flat spot" on take off. To be honest the car has always been like that, ie, I have to "wind it up" a bit to get it to move, I thought it was just a bit of latency. I thought this was normal but he says it's not. Any ideas on what could cause this? It's an M20B20 engine.

    Thanks,

    Shaun

  2. #2
    Join Date
    Oct 2004
    Location
    Gainesville, FL
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    549

    Default

    My 530 is like that as well. until 30mph, the car basically rolls forward under gravity. It's always been that way. I'm pretty sure anything short of a diesel could beat me from 0-30. somedays its better than others. the cold helps a lot.

  3. #3
    Join Date
    Mar 2004
    Location
    Phoenix, AZ
    Posts
    285

    Default I thought it was a "feature" of an inline six........no?

    Could be wrong.....



    Quote Originally Posted by E34-520iSE
    Hi all! I let my Father in law drive my E34 today. He was complaining about a big "flat spot" on take off. To be honest the car has always been like that, ie, I have to "wind it up" a bit to get it to move, I thought it was just a bit of latency. I thought this was normal but he says it's not. Any ideas on what could cause this? It's an M20B20 engine.

    Thanks,

    Shaun

  4. #4
    Join Date
    Mar 2005
    Location
    South North CA, Bay Area
    Posts
    247

    Default

    M20B20 engine + lots of weight

  5. #5
    Join Date
    Mar 2005
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    Hockinson, Washington
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    2,499

    Default

    Perhaps a high-lockup torque converter is in order?
    Lowered with blue h&r(?) springs, Bilsteins, tint, 19# design 3 injectors, Dual Magnaflow
    southwest WA

  6. #6
    Join Date
    Nov 2004
    Location
    Split, Croatia
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    718

    Default

    Quote Originally Posted by E34-520iSE
    Hi all! I let my Father in law drive my E34 today. He was complaining about a big "flat spot" on take off. To be honest the car has always been like that, ie, I have to "wind it up" a bit to get it to move, I thought it was just a bit of latency. I thought this was normal but he says it's not. Any ideas on what could cause this? It's an M20B20 engine.
    129 HP in a car that weights 1.5 tons = not a good idea. Don't expect BMW-like performance out of it. Most of the 5ers are not made for traffic light racing anyway, they're simply too heavy. Consider it a comfortable highway cruiser.
    BMW E34 528i, M52B28 + M50 manifold, Remus exhaust, ///M Parallel Spoke 18" rims

  7. #7
    Join Date
    Feb 2005
    Location
    kIWI LAND(New Zealand)
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    183

    Default

    A chip may help.mmmmmmchip's
    89 535 272,000km auto Euro

  8. #8
    Join Date
    Nov 2004
    Location
    Gateshead,UK
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    Default

    Thanks for the replies everyone! I never had any issues with the "slow to rev up from idle" phenomenon. Just when someone else drove it and said it doesn't seem right makes me want to find out why. The car is a 5-speed manual. I have now realised there is quite a delay between me pressing the throttle pedal and the engine responding (between 1 & 2 seconds), and that's before I start releasing the clutch!
    Is it a big valve/little chamber design issue? Are M20 engines "slow breathers" at low rpm? What's your thoughts on this?

    Cheers,

    Shaun

  9. #9
    Join Date
    Dec 2003
    Location
    Eastern Tennessee USi
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    14,839

    Default

    all bmw engines are made for higher rpm operation and are turds at low rpms. the engines arent made for low speed dragracing but for high speed use, the low rpm turd area is normal. I put in a higher ratio rear end gear which makes the car respund about 10 mph earlier but still until that point its a turd.
    95 E34 530I V2.37
    ===========
    Those who make peaceful revolution impossible will make violent revolution inevitable.

    John F. Kennedy

  10. #10
    Join Date
    Jan 2004
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    Benneton (United Colors of)
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    Default

    Quote Originally Posted by JD525IA
    Could be wrong.....

    the crankshaft on an inline 6 has to be twice as long as a v6, and almost twice as long as a v8, thus people say that the power takes longer to build up in it. however, the power "feature" in an inline 6 is that the power builds up more "linearly", ie more smoothly and that he engine offers much less vibration than the v-configurations.
    "..Torchinski v. Peterson that it is legal to carry a concealed weapon, so long the weapon is totally slick like a huge ass machine gun that you carry under a trench coat, like in the Matrix."


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