hi guys,

I own a polo gt tdi pretty much the same car as the fabia.

A problem I have with it is that its really bad on fuel, im averaging 25mpg locally and max 30mpg on motorways. I dont drive it like its stolen apart from the odd blast, but im only getting 250-270 miles to a compltely full tank off approx 44 litres.

My wifes car a polo tdi sport (100bhp) 2004 model always gets around 46mpg on exactly the same journeys.

I used her car for the commute to work for 3 weeks before i bought my polo gt and was always getting around 380 miles to a tank. On my car i only get 250-270 on the same journeys at the same speeds etc

My polo gt is standard, wifes is remapped to approx 135bhp.

Had it booked in at VW but was told low MPG is due to weather???? told them that wifes car does more mpg in exactly same weather but was told theres no problem with my car.

My car was serviced at VW few weeks ago, so is not in need of a service?

Any of you guys have an idea what it could be?

Cheers

Under 30mpg, I'd take it to the dealers mate, thats rediculously low...

As Tom says, that is seriously low (my Scooby would do 30mpg on the motoway!) One thing to check is that you don't have a seized caliper as that could well be bringing your mpg down. Other things to check would be air filter and MAF, but the car would be very smokey if they were at fault.

Chris

The colder temps will potentially reduce economy a bit due to the denser air allowing higher fuelling rates - although if you drive at the same speeds all the time, it won't make a massive difference. So first of all, I'd recommend replacing the air filter (a paper one is OK as long as you replace it every 10k IMO - although others recommend a panel filter!) If that doesn't help, get a diagnostic scan done, as one of the sensors could be faulty. Also, does the mpg displayed on the trip computer tie in with the actual amount of fuel you're using? The computer's notoriously over-optimistic, so maybe it's just the trip computer that's playing up???

The car has been to the main dealers. Its had the 20000 miles long life service 4 weeks ago. It was also MOT'd by them last week so a seized caliper should have been identified. Car is still under warranty for two more weeks!

Main dealers cant identify a problem.

I read somewhere that EGR problems can casue this? am i right?

That is a bit low!!

I'd say maf at a guess... but to be hitting 30mpg on the motorway! Ouch!

Mine hits 50 - 60mpg comfortably, but I only get 300-350 miles from a tank as I do alot of town work.

even when i completely brim the tank, and then vent it to get a few more litres in. When I get back in and look at the trip computer it shows that my mileage range is 290 miles. the other polo always states 420-430 on a full tanl.

Even the average MPG computer only reads 28-29 mpg locally and we all know that the computer is optimistic.

It seems as the car knows its only going to do 250 -270 miles max on a tank.

Its worse than a petrol guzzler with this low mpg......whats the point of a diesel?

Don't know the symptoms of a dodgy EGR are, but you can disconnect your MAF to see if that makes any difference...?

There is a point when its working properly... reset all the trips and the ECU, see if it helps.

RUn vagcom and see if the maf is faulty?

MAF is fine i think. pick up is fine on performance.

even with it diconnected car behaves the same.

There is a point when its working properly... reset all the trips and the ECU, see if it helps.

RUn vagcom and see if the maf is faulty?

how do i reset the ECU?

Very bizarre... something not quite right though!

I think via vagcom? Or do you disconnect the battery? Never done iot but told it helps occasionally

Hmmm, have you got a fuel leak??

how do i reset the ECU?

Legend has it that the ECU can be reset by turning the key two clicks (so that the dash lights up but the engine isn't started) and leaving it for a couple of minutes. This supposedly restores factory settings, and although it cleared an EPC light on SWMBO's car, the fault may have been one of those things that would have gone away if we'd just turned the car off and restarted it normally anyway!!! Got to be worth a try, though???

Hmmm, have you got a fuel leak??

This would be picked up by having a vast difference between the OB Trip computer and the brim to brim method.

Or if you have a drive leave it on there for a few hours then move it to see if there is any dampness on the floor - not so easy in these weather conditions but if its dry then it saves you jacking up the car for a look.

You could always take it down to kwik fit and get them to check it if its beyond your mechanical engineering abilities.

This would be picked up by having a vast difference between the OB Trip computer and the brim to brim method.

Or if you have a drive leave it on there for a few hours then move it to see if there is any dampness on the floor - not so easy in these weather conditions but if its dry then it saves you jacking up the car for a look.

You could always take it down to kwik fit and get them to check it if its beyond your mechanical engineering abilities.

Not necessarily - it depends on exactly how the trip computer calculates fuel consumption. If it works by using the input to the fuel pump, then yes, it would show a discrepancy. But if it works by using the rate of fall of the fuel level in the tank, then it wouldn't. My money's still on a sensor / ECU fault...

Not necessarily - it depends on exactly how the trip computer calculates fuel consumption. If it works by using the input to the fuel pump, then yes, it would show a discrepancy. But if it works by using the rate of fall of the fuel level in the tank, then it wouldn't. My money's still on a sensor / ECU fault...

You could be right it would totally depend on where the flow meter is.

Actually thinking about it VAG's now have a range function on them which would mean Fuel tank obviously so given that it would make total sense to have all those sensors in one location.

To the Polo GT TDI 130 owner - on your trip computer you will have a function which shows ave mpg for the current trip ave MPG for the last 2000miles and instant mpg put your car into 6th on a flat motorway and hold it at 70mph let us know what instant mpg readings your getting.

Also - no indication of milage??

When I got the Gt TDI 115 the first 10k it would range 45-48mpg but after that the ave sat pretty much at 55-60 with some trips into the 70+mpg range.

AFAIK, the onboard computer bases the range on the last 50 miles of driving so if you were getting an mpg of 30mpg at the time you filled up, then the range will be based on that.

Chris

MAF is fine i think. pick up is fine on performance.

even with it diconnected car behaves the same.

...So disconnecting the MAF makes no difference to performance? That don't sound right.

...So disconnecting the MAF makes no difference to performance? That don't sound right.

Never having run a VAG TDI, but glossing over quite a few threads on here, I will second the above statement, in fact with/without MAF plugged in is normally a normal good/bad MAF test I think. Quick your warranty is escaping!

To further the above, my TDI is more like an SDI with the MAF disconnected!

If there's no difference with the MAF disconnected, doesn't that indicate that it's faulty?

Think so...