Megane 250 revs fluctuates high load

Discussion in 'Mechanical - Engine, Gearbox, Exhaust etc' started by Meganechris, Apr 17, 2024.

  1. I’ve recently sorted my megane out after buying a lemon , new turbo recon engine 630cc injectors , Wagner decat etc the list goes on , it was mapped at EFI the other week no issues stage 2 315 bhp and 350 lbs ft . The only thing he noticed was coming onto boost around 3200 he had to limit torque due to det he said if head skimmed may have increased compression but was fine above this. I’ve attached the graph.
    Anyway all was well until I’ve noticed under high load mostly in 5th and 6th full throttle high rpm I notice the exhaust note is not constant . You can hear the whooshing going on and off slightly , my boost gauge doesn’t move 21 psi hold but you can see the rpm needle going up and down very slightly as it rises and doesn’t feel as quick is it should . I know something is not right , I’ve tried a new n75 last week, but plugs are new ngk 8 and gapped to 0.6 and brand new Bosch coils , timing belt etc was all before mapping . Any advise what to check thanks
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  2. Take it back to Chris and ask him to spin it back up on the dyno.
    It would be much better than loads of people on the internet trying to diagnose it.

    I note your other thread about clutch slip too - Chris will be able to give you a definitive answer on that also.
  3. I would suspect the fuel pump, these cars are getting on a bit now, but as RS says, best to get a controlled test on the rollers
  4. I did think about this tbh would a Bosch one be ok ? Any uprated ones you can recommend ? Only other thing I thought was waste gate opening slightly and shutting in high rpms
  5. Just looking for a few pointers really but yes going back on rollers is a better option
  6. I have fitted a DW65c to my old 265, it's not a straight fit like the 225/R26 one, but it is doable with a bit of care and cutting.

    Wastegate is controlled by the N75 valve but as you have already changed that, it's something else.
    You will get more boost mid range than high rpm's, so look for a hole or split in the pipes to the N75, or even a loose fitting.
  7. Found your thread on fuel pump fitting thanks , just confused how the lower fuel filter seals on the pump after you cut the hole out the middle? I’ve new tight silicone hose on the n75 , other option is boost leak check but most stuff is new on it all tbh going to do the fuel pump anyway worth upgrading
  8. Ordered a new full Bosch sender and pump so see how that goes for a spare actuator here too I’ll report back
  9. Update
    Fit a new Bosch pump and sender and brand new flow matched 630cc injectors mine were second hand so might not have been the best , also the only sensor left to replace was the map sensor in the charge pipe , also new plugs and all back to full boost top gears , may book a cheap day at blyton to have a shake down on its first track day

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