Q - Golf V GTI - why did economy change ?

[anonymous-user]

[redacted]

[sleep envy]

have you checked to see if you are getting 40mpg?

could be just a duff 'puter

[sleep envy]

are you fuelling at the same place?

[sleep envy]

could it be a fuel issue?

[excel monkey]

If you're only doing 3k miles in 16 months, that's equivalent to putting in a full tank of fuel every 2 months.

Can fuel go stale in that time?

I found the economy on my 320d dropped off by about 5mpg during the recent cold spell, but on a long run last weekend it was back to normal.

[Deva Link]

anonymous said:

[redacted]

What do you mean by "changed back"? Is the display showing average over the trip, or instantaneous MPG? Or did you stop and it reset mid trip?

[Deva Link]

I do the same - except I'm targetting 50MPG.

My car is *always* more economical heading South than North - is it really uphill, or perhaps I'm just keen to get home!

Off the top of my head the only thing that could cause a sudden change is one of the temp sensors telling the ecu that the engine was cold, so overfueling it, and that suddenly correcting itself. Could be MAF, and it cleaned itself.

Edited by Deva Link on Tuesday 16th March 15:01

[SMB]

Firstly the ECU does learn, regardless of what VW says, having had a car for 4.5 yrs, and reset the ecu myself a few times it learns the running of the car, fuel type as it goes. Yoyu can feel and measure the difference in consumption.

Other items to consider, did you have lights, aircon, etc etc on in one direction? Was there a temperature change?
Did the average reset after the first journey or did it count it as one trip? After 37K miles I've long term averaged 35mpg. Only changed when resetting ecu, change of fuel type or changing driving behaviour.

[tylerama]

I thought the instantaneous was jsut that ie at that moemnt that's the mpg - so when I take my foot off the gas it goes up to 500mpg or something daft, then when WOT it's about 5mpg. Surely the average is the one to be watching ?

[tylerama]

anonymous said:

[redacted]

Ah, I see, that makes sense. I've never even used the instant at all really, as it's just so variable.

[997GT3]

I got lower mpg today than a couple of days ago on an identical journey because irt was windier. At 70mph a headwind will reduce mpg quite abit. As said above, it's downhill heading south through Lancashire towards Cheshire, uphill going north. Also, weight of fule may be a factor.