Dodgy MFA or Poor Fuel Consumption??

[Procomp]

Hi
Looking for some advise from the wise

My on board computer is showing I'm getting about 15-6mpg at present.  This is even after I've reset it and drove it gently over a period on a long run in 5th gear on motorway type crusing.  Not yet done the calculation of full tank of fuel v mileage covered; as I've not really had the opportunity to drive the car over a longer distance/period. 

I was wondering if there were any common faults with the MFA's to consider of if there is a set up tuning issue to think about?  The temperature, clock and journey travelled info is spot on on the MFA.

My engine is running fine it appears.  There ar no obvious signs of excessive fuel burning...smoke, smells, etc.  It's been recently serviced, so it has new plugs, leads, dizzy/rota, etc.  I got the car as a non-runner and had to fit a new fuel pump & filter, plus the fuel metering unit was knackered, so I've fitted a 2nd hand unit.  The car goes really well and as this is my first GTI (16V), I'm not sure of what to expect in terms of fuel consumption.

Any help, guidence or advise is welcome as usual 
Thanks
G

[Horney]

The MPG reading works off a vacuum feed from the inlet manifold. A little pipe is conected to the back of the clocks. It's likely this is either completley missing, diconnected or has a crack in it causing the reading to be way out.

Nick

[Procomp]

Nick
Cheers for the info......will look to see if first off I have the vacuum pipe and if so, that it's connected and in good working order.

G

[Ben Lessani]

My MFA is just stupid only thing that works is the trip counter, MPG never gets above 12 - even though I'm hitting about 35-45 mpg most of the time.

[JC]

only way u will get a true MPG figure,

fill up - reset trip - drive - fill up work out figures.

but as your speedo and trip will be out then it wont be that good a figure anyway 

[theclash]

i get about 140 mile to 20 quid thats town driving but petrols pound a litre so i dont know if thats good or bad.

[JC]

oooooooooo maths this time of night


20 quid = 20 litres

20 /  4.454 = 4.49  gallons

140 / 4.49 = 31.2 mpg

I think 

[theclash]

oooooooooo maths this time of night


20 quid = 20 litres

20 /  4.454 = 4.49  gallons

140 / 4.49 = 31.2 mpg

I think 

flippin eck.... i wish i listend in school   

[JC]

didnt say it was rite 

[Jay]

Flippen heck, doing maths at this time of night 

http://www.torquecars.com/tools/uk-mpg-calculator.php

Says 31.82 so not a bad calculation Chuff