flat spot or lag at 3,000 RPM
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  1. #1
    1000+ Posts n b j's Avatar
    Join Date
    Jun 2003

    flat spot or lag at 3,000 RPM

    This post is not in relating to my Peugeot, but instead to my PorscheRS which flat spots badly at 3,000RPM if you are not driving it hard and the revs slowly rise to 3,000 it will flat spot or lag, you can't get the power on quickly and have to wait until the revs climb (surging briefly through the rev range ) to about 4,000 before you have the power back. Once over 4,000 rpm the problem is gone and you can wind the engine out to over 8k

    The problem is not there if you floor it and drive it hard through 1st, then into 2nd, 3rd, etc... no flat spot, no lag.


    My dad and I have our own opinions on why it does it and so does our mechanic...

    What I was wondering is what are peoples opinions out there as to what the issue is and/or what causes it...? since this is a techinically minded forum and all

    Oh yeah, this is a 1973 car which still has it's original engine, the engine only has 70,000 miles on the clock.
    "Do my eyes deceive me, or is Senna's Lotus sounding rough ?" - Murray Walker
    206XR 1.6ltr - SOLD
    BMW E36 325i Coupe
    73 Porsche 911RS

  2. #2
    mistareno's Avatar
    Join Date
    Nov 2002
    no vacuum advance??

    This would cause the engine to behave normaly under high load situations, but flatspot under light throttle/partial load circumstances.

    It is the most obvious/cheapest thing to check.

  3. #3
    Join Date
    Jan 2003
    Burpengary, Queensland
    HI NBJ,
    What type of induction does the RS have. Does it have the mechanical injection or side draught webbers ?
    Forgive my ignorance.

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