Low mpg following hole in turbo pipe

[daveyboy123]

Hello all, just looking for some help and reassurance.

My car a tdci 1.6 Ford Focus 05 plate, recently had a hole in one of the turbo hoses. I noticed this as there was a loud air noise, sort of like a fan being on when accelerating and also I noticed that my mpg went down from around 50-55mpg to about 40mpg.

I got the full pipe replaced and all is back to normal, no noise and car much more responsive again but  the mpg still seems to be around the 40-41mpg Mark so seem a bit low. 

Will it take a few fill ups for the ecu to recalibrate the new pipe and use less fuel etc or should this happen instantly?

It was fine up until the whole in the pipe but now it's fixed I don't understand why the mpg hasn't increased again.

Thank you.