Misfire only over 6000rpm on my VTS

  1. Regular Poster Joined: Apr 2011 Wrexham, North Wales Posts: 307 Gold Saxo VTS & a Yellow S2000
    #1
    Hi, I've got a misfire on my ITB'd VTS. Weird thing is that it only occurs above 6000rpms. Makes it something that hasn't forced me to stop using the car but I'm struggling to find out why its doing it.

    So far i have:
    Replaced coilpack
    Replaced injectors
    Tried different ECU

    Still doesn't like high RPM's. Anyone got suggestions what to try or do next? I've just purchased a new knock sensor for it & I will change spark plugs soon.

    Also, i've searched loads on here & other forums. I think it may be a bad earth somewhere or even a vacuum leak but I'm unsure tbh.
  2. Saxperience Hardcore! Joined: Dec 2007 smurfland. Posts: 17346 Ex saxo owner.
    #2
    Why a new knock sensor,is it pinking?
  3. Frequent Poster Joined: Nov 2009 Posts: 576
    #3
    Check fuel pressure at the top end.
  4. Frequent Poster Joined: Nov 2009 Posts: 576
    #4
    Or check delivery from the return line. You need at least 20cc/second.
  5. Regular Poster Joined: Feb 2016 manchester Posts: 256
    #5
    Fueling or spark.


    Could be coil/plugs/leads/earth.
  6. Regular Poster Joined: Apr 2011 Wrexham, North Wales Posts: 307 Gold Saxo VTS & a Yellow S2000
    #6
    Ok, cheers for the help so far. I have just replaced the fuel pump & fuel filter. I also changed the coilpack & spark plugs for a final time.

    Went out for a test drive & problem still occurs but here is the thing....It only occurs when I'm flat to the floor at over 6000rpm.

    If I am half or two thirds throttle, It does not occurs & revs right up.

    I'm going to take the car to a garage soon because I'm off Nurburgring on the 29th April. I will ask them to look for the 20cc/second (cheers Wayne) because I'm not sure what to use or how to do that.

    By the way, the knock sensor I haven't checked, just read it on another forum. Caused some guys Subaru to misfire at high revs.