Mpg Trip Computer Problems, Turbo Failure

[SonnySiggs]

Please Help!! Since getting my Focus back from repair (Turbo was about to fail due to oil carbonization so was refurbished and sent back with modifications carried out by dealer) i have had a problem with the mpg on the trip computer. Say after doing a 20 mile trip i stop the car at 60mpg. When i go out to the car the next day, or after a few hours, i turn the ignition og and it woul come up as say 53mpg, and then when i start the engine it will drop again to say 47mpg! Its never done this before and is really annoying the hell out of me!!

Before we get onto the topic of the turbo problem my car is 2009 1.6tdci zetec with 44,000 and has just had a service due to the oil change for turbo repair. A week after they fixed the turbo problem the pipe blew off the turbo on the motorway and i had to crawl back to the garage so they couldnt have put it back properly...

Now, it just doesnt feel right driving it. Feels like its not smooth as if someone is tickling the accelerator and jumpy!

[NorthSussex]

Normally the trip computer settles down a to give an average mpg after few hundred miles providing you don't keep resetting it, only reset it if you want to check an mpg for 1 journey.