Poor MPG after timing belt change

[Veyron]

Hi I had my timing belt and water pump changed about 2 weeks ago at a VAG specialist, using genuine parts. Though I’ve noticed my MPG seems to have dropped off a cliff since! Was seeing 70MPG on the motorway and now I’m barely seeing 50!

The mrs did put a tank of Asda fuel in just after which I’m hoping is the reason but I think that’s just me being optimistic!

I did read online that after a timing belt change the battery should be disconnected then the engine left to idle for 30 mins to recalibrate the ECU? I asked the garage who said that’s not needed and that they didn’t do it, but told me to come back if still seeing low MPG. Just wondered if anybody else has seen this?

Thanks

Car is a 2013 CR150

 

[Deleted member 123178]

Are you sure you're not just paying more attention to the mpg figures after the work? Doubt you'll see anywhere near 70mpg in the middle of winter unless you're drafting a truck downhill.

 

[KXL]

I remember when I had my 63 plate 2.0TDI Leon, on Shell/Esso/BP fuel a said jouney would always return 50-52mpg (done about 50 or more of these journies). One day was curious and put in £10 worth of Tesco diesel from nearly empty. And that one journey the car said I did 45mpg only!

 

[Veyron]

Yeah it’s definately reduced loads! Did a urban trip today in eco mode driving like a granny and averaged 26mpg! No stop start traffic or long idling periods either

 

[SRGTD]

@Veyron; are you using the mpg figures calculated by your car’s fuel computer? Just a thought, but is it possible you might have an issue with your car’s fuel computer rather than an actual worsening in your fuel consumption? Have you manually calculated the mpg on a full tank of fuel and compared this to the mpg calculated by your car’s computer?

 

[Veyron]

@Veyron; are you using the mpg figures calculated by your car’s fuel computer? Just a thought, but is it possible you might have an issue with your car’s fuel computer rather than an actual worsening in your fuel consumption? Have you manually calculated the mpg on a full tank of fuel and compared this to the mpg calculated by your car’s computer?

Hi, yes using the computer but it seems correct. I’ve used half a tank having only done 180 miles!