.........When i reset my ecu the car goes great, then after a couple of weeks it seems the the turbo isn't as good.
Any thoughts ?
The car also sounds as if its missing a beat, not a missfire just a small imperfection.
Even when reving to 1500 rpm whilst not moving you can hear it so its not just an idle problem.
Can anyone help please.

Thanks

 

Drop off in performance suggests it might be retarding the ignition for some reason. The solution is not to keep resetting the ECU but to find an underlying reason. If it is a Jap import some say they do lose performance over time after reset as they advance the ignition after reset for 100 RON fuel which in Scotland would mean SUL + double dose most octane boosters.

What model, mods, octane?

Consider amongst others - plugs, plug gap, MAF sensor, lambda sensor, coil packs etc etc.