Hello,

I have been having this problem with my car since i bought it in February and feel like i have read every forum concerning the problem and tried nearly everything necessary, so i will now try to describe it as best as possible and hope someone may have a clue as to the cause.

When driving the car, its revs through the range well in 1st and 2nd, however in 3rd gear and higher above 3,000 revs the car seems to enter a prolonged flat spot, losing power but not always sending it into limp mode, when i reduce speed and use less revs the car does not flat spot and will continue to accelerate agin until just above 3,000. In addition and likely the same problem, the car often and easily enters into limp mode when pulling up a hill or just accelerating from low revs in 3rd gear and above. Once restarted the car returns to 'normal mode'.

Since reading many forums of members with similar problems i have been lead to believe something could be causing the turbo to 'overboost'. I have even listened to the turbo when reving the engine and i can hear a 'whirring' noise from very early in the revs and once stopped reving the whirring noise takes a slight while longer to stop. I do not know whether this is normal for the turbo or not so some reference to this would be great.

As i hope there is nothing wrong with the turbo i have done a few other things:

Firstly i replaced the VNT actuator, believing that the membrane inside the actuator could be weak. I also checked to see if the vanes moved freely inside the turbo by flicking the actuator lever up and down which does so easily.

Next i took off the inlet manifold and EGR valve to check to see if there was an excess of carbon build up. Although there was some, it was nothing significant, and once i cleaned it there was barely a smear.

Shortly after i replaced all of the vacuum pipes to rule out any vacuum leaks. I then also swopped the two N75 valves over to make sure it was not this.

All of this has made no difference to the problem and the car still behaves the same.

If there is anyone who could advise me of what i could try next or in their opinion is the likely cause i would be very grateful, and will continue posting so that others may find this useful.

Thanks in advance,

Jordan