Seriously bad fuel economy

[Balf2k]

I have recently (since Jabba remap) been getting really bad fuel economy (even driving sensibly / off boost) and it seems to be getting worse. I do a 22 mile run to work, half motorway and half A roads and the other night I got home, looked down and 17.7mpg average was displayed WTF. I know when it was mapped @ Jabba Mike said the Lambda had a fault. I cleared it with Vag-cam and it hasn't come back since. The weird thing is... the car seems MORE economical around town, driving at 30mph than cruising at 70mph. I can pull up on my drive after a run and sat there parked, the mpg still drops, I just got home and the computer said 20.1mpg, I let the car run for a couple of mins and the economy was dropping even though I was stationary, it dropped to 9mpg before I got sick of looking at the f@~#+=g thing and turned it off. I have repeatedly scanned the car with Vag-com and there are NO DTC's. Please help

 

[daniel_owen_uk]

Let me get this straight you are sat still with the engine running and wondering why the MPG is going down?

THE ENGINE IS RUNNING, BUT YOU AREN'T GOING ANYWHERE

 

[andycupra]

doh!

if you drive at 30 and dont end up stuck in traffic you will get better mileage than at 70.

if you drive at 0mph you will of course get no miles per gallon. or if you leave it running after a run you will be using more fuel and not adding to the mileage.
so the mpg will go down.

now while 17 mpg is very bad indeed and suggests a problem, your understanding of how mpg is calculated is worse still. a piss take?

what did you get mpg before the remap?

 

[Balf2k]

Before the map, a typical drive that now returns 18mpg would have been probably 30. Its a Big difference. And as for the stationary mpg falling, I mean I can see it falling fairly quickly, even after a 20 mile or so run. That's the reason I thought it was strange. Before the remap I could get about 32 - 35mpg cruising at 70, now its real bad.

 

[December]

How can i check the fuel economy in my car ?

 

[ChrisUK]

Use the onboard computer (if you have one), or work it out manually over a week!

Sell the cupra & get a TDI - 55mpg on a 25 mile mixed run, remapped & not taking it easy

 

[December]

I got a TDI ; How do i use the onboard computer to find out my fuel economy ?
I assume you're talking about the computer i access on the climate control ?

 

[m0rk]

Before the map, a typical drive that now returns 18mpg would have been probably 30. Its a Big difference. And as for the stationary mpg falling, I mean I can see it falling fairly quickly, even after a 20 mile or so run. That's the reason I thought it was strange. Before the remap I could get about 32 - 35mpg cruising at 70, now its real bad.

I would try a throttle body / ECU reset

and then log the ECU for air flow (MAF). Then log Lambda probe function too

 

[jonathanp]

could a faulty coolant sensor also cause a similar problem?

 

[ponydust]

Before the map, a typical drive that now returns 18mpg would have been probably 30. Its a Big difference. And as for the stationary mpg falling, I mean I can see it falling fairly quickly, even after a 20 mile or so run. That's the reason I thought it was strange. Before the remap I could get about 32 - 35mpg cruising at 70, now its real bad.

Be happy that you've got a 210bph car in the first place and stop it with these silly remaps!! Is the 12 mpg difference worth the extra power - if it is, theres your answer

 

[m0rk]

yes, it will report back to the ECU that it's not yet warmed up and will remain 'on choke' - but does normally throw a MIL light and Fault code.

If ignored, it will overfuel, and that will bugger the lambda probe and cat very quickly.

 

[December]

Yeah, i feel the same way as ponydust

 

[m0rk]

if all checks out though, it may be a problem with the map?

 

[ponydust]

Yeah, i feel the same way as ponydust

Thanks mate - it's probably the fact i don't really understand!!

 

[andycupra]

I got a TDI ; How do i use the onboard computer to find out my fuel economy ?
I assume you're talking about the computer i access on the climate control ?

no the computer is via the indicator stalk.

you can work out your fuel econamy manually.

best way to do this it:
fill the tank.
reset trip.
when you next fill up make a note of mileage and litres needed to fill tank.

5 litres is 1.1 gallons.
so eg 50 litres would be 11 gallons.
or divide litres by 5 and multiply by1.1 to get gallons.

eg if you get 350 miles out of a tankfull and it takes 53 litres to fill up:
53/5*1.1=11.66 gallons

350/11.66= 30.02 mpg

a rough guide based on the leon fuel tank filled up shortly after the warning light comes on (53 litres):
200 miles = 17.2 mpg
250 miles = 21.4 mpg
300 miles = 25.7 mpg
350 miles = 30 mpg
400 miles = 34.3 mpg
450 miles = 38.6 mpg
500 miles = 42.9 mpg

 

[December]

I just converted liters to gallons and km to miles and apparently i get about 45~50mpg on the highway and 35mpg in really bad traffic downtown .

Basicly i go 100km with 4.5 ~ 5 litters of gas on the highway and 6.5 litters / 100km in bad traffic.

 

[Brucel]

I was remapped and it made the car more economical.....

That reall is bad economy!!!

 

[Ibiza Cupra]

Who actually cares about economy????

Who actually gets there car remapped to see wot there Ave MPG goes to????

Start enjoying the fact you have in the region of 260bhp!!!!! Thats an extra 50bhp!!!!!

Fuel economy will be the last of your worries, especially when you get addicted to the loud pedal and you need new front tyres every month or 2!!!!

 

[December]

I care alot about economy

 

[Balf2k]

The car was fine when mapped, it slowly got worse, in my opinion, going by previous 1.8T cars I have owned, remaps do make them MORE economical if you drive sensibly, it's only when you're on full boost that the fuelling is seriously increased, Mike at Jabba confirmed that fuelling for pretty much anything under 10 - 12 PSI of boost (standard boost pressure) is untouched so really I shouldn't be getting a bad economy hit. Remap's do NOT mean that cars drink lots more fuel, only if you drive with a lead foot. Its simple, an engine makes more power by getting air through the engine faster, the increase in more air also needs more fuel mixed with it to keep safe A/F ratio's, so what im trying to say is, if you use all 280BHP of a remapped car then yeah it's gonna drink like a fish but if you drive sensibly then fuelling should be no worse than the base map. Hope that makes sense