250 Megane RS250 Boost/fuel problem?

Discussion in 'Mechanical - Engine, Gearbox, Exhaust etc' started by linusviklund, May 6, 2020.

  1. Hello!

    Recently ive gotten a problem with my Megane 3.
    During full on acceleration, at around 5k+ rpms it kind of cuts/stutters on an off for a sec.
    Loss of power during this time.
    Kinda like it doesnt get enough fuel?

    The problem only occurs sometimes, but recently its been a lot more often.

    Car is fitted with an KTR catback exhaust, downpipe, intercooler and stage 3 map. Also an forged BoV.

    Attached is a video i took on the phone, kinda hard to get in on tape tho.

    All help is appreciated!

     
  2. Mine didn’t sound quite like that but above 5,000 RPM and particularly bad near redline, my car would start misfiring. At first we didn’t think it was the spark plugs as they were brand new. After checking and cleaning the coils the misfire was still there. Changed the plugs and the misfire disappeared. One of the plugs was faulty which you couldn’t tell just by inspecting it.
     
  3. could be several issues:

    bad mapping
    plugs
    coil pack
    fuel pump pressure
    blocked chassis fuel filter
     
  4. @bobsan
    @DOOOOK
    Thanks, both of you.
    Im going to order some new plugs and try.
    If not i guess ill go through your list.

    Any suggestion on how i should try the diffrent things without replacing them?
     
  5. gap plugs to 0.6mm

    how old are coil packs, fuel pump (in tank) and fuel filter

    has it been mapped by who ??
     
  6. If you are buying new plugs, go one number higher, so that should be BKR8EIX and gap them to 0.6mm, this is a must if it's been mapped, if not its still worth doing.
     
  7. Car has been mapped by Autotech in Sweden, used to be specialist on Meganes. I dont think its the same owner still tho.
    Oil packs, fuel pump and fuel filter have never been changed by me, ive owned it for 1.5 years.
    Not sure when previous owner did it.

    Also, the car was mapped before i bought it.
    The problem started recently.
     
  8. Ill look into that, thanks.
    Any specific fuel filter i should look for aswell?
     
  9. any really, not the cheapest middle of the road price i would go for
     
  10. Clean plugs up and regap them to 0.6, wheni first changed mine, i didnt gap them, and it felt no different to the originals, took them back out and clean up and gapped them to 0.6, and it felt a different car.
     
    ianplymouth likes this.
  11. Yeah.
    Already got new plugs on the way, so ill gap them to 0.6 and see how it does.
     
  12. I tried regapping my current plugs to 0.6
    Before i had 0.8
    No problem after test driving.
    But if the problem is solved, im not sure.
    Guess i will have to see after driving a couple of days
     
    ianplymouth likes this.
  13. So, a little update.
    Been driving the car pretty hard since Thursday.
    And the problem hasnt occured a single time.

    Is it really that sensitiv? From 0.8 to 0.6 spark plug gap?

    I still have new plugs on the way wich im going to change to, since its never bad with new plugs.

    Thanks again guys for the help, really appreciate it!
     
  14. as the car is forced induction it can blow the spark out, so by reducing the gap it makes a stronger spark, so then it's harder for it to be blown out.

    glad its sorted :sunglasses:
     
  15. I set the spark plugs to 0.6 per recommendations from this forum and with the Stage 2 car mapped and the engine started to misfire exactly like the video example and occasionally.
    So I bought new spark plugs and installed them without altering and the engine felt less energetic but there were no glitches.
    Perhaps less aggressive Gap regulation is the perfect solution.
    Spark Plug Gap OEM...? 0,7 or 0,8?
    Excuse my English..:sweatsmile:
     
  16. Standard plugs ungapped should be absolutely fine on your setup.

    My guess is the tune makes it pig rich on boost, giving the plugs a hard time!
     
  17. Hi folk
    Thanks for the replies so far.
    The alarm is new but was fitted after the fault materialised it would appear. There was a bit of a panic that the car was very low on fuel before it was MOTd and that was before the alarm was fitted. It subsequently turns out that the car only took 10 gallons to brim the tank, not 20.
     

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