Mk1 Fabia vrs very poor mpg 320 miles per tank

[Crl123]

Bought a mk1 2004 Fabia vrs in April when I got the car was only seeing 33 mpg driving at 50mph 28mpg on motorway, had some lag got it remapped at ##!!##h which sorted it, since then it's had a full service new diesel filter air filter oil change etc, a ##!!##h 1752 turbo straight through exhaust and de cat, still poor mpg and ##!!##h can't get it to wanted power due to a furlong issue which they can't find only thing they said is a new cam sensor that I need any ideas, running at 190bhp

[Ootohere]

Maybe can run at 190bhp. But you are probably wanting the mpg when just driving using half that

Like most of the time. Maybe the Fabia mk1 section will be the place that you get help with it.

[KenONeill]

Am I reading this correctly? Your Furbie was giving poor mpg so your first move was to remap it rather than find the actual fault (I'd guess CTS always reading cold which is easy enough to prove with VCDS or VAG diagnostics).

[Crl123]

Yeah when I got it mapped they had to give it more fuel to reduce the lag but still seeing poor mpg, where could I get it looked at?

[KenONeill]

Check our VCDS forum for someone in Cumbria. I've never had mechanical work done in the county so can't advise on good garages.

[andsoutham]

are your brakes binding? go for a drive but go easy on the brakes then when you get back see how hot the wheels are to touch, these cars have a tendency for the handbrake to stick on a bit which could be your problem

 

what tyres are you using and what pressures do you run them on?

 

are you going off the MPG from the onboard computer? these can be pretty inaccurate. The best way to get accurate MPG is to brim the tank, reset the trip, drive it, fill back up again and see how much fuel you have used compared to how many miles you have covered.

 

i would also get your stop screw and actuator settings on your turbo checked with VCDS, there will be a guide somewhere on how to do this. 

[GLIDN]

I too have been at the quest of making my VRS more fuel efficient.

Started off with basics. I was barely getting 350-400kms to a tank of diesel.

 

After browsing the forum and seeing what others had done.

I decided to get a DNA map. As it turned out I had a horrible MAP on the car when purschasing a few months ago.

 

Everything replaced to date.

New Fuel filter

Ran Liqui-Moly Diesel Purge through the injector pump

Liqui Moly Super Diesel Cetane additive in the tank 

Another Liqui Moly product to clean the EGR and Intake Manifold (I would say it's not as bad as some of the pictures seen on the forum)

New OEM Air filter. Original was virtually black

 

After all of this I went from 8.5-10km/L in town and 12.4-13.7km/L on the open road to

13-14km/L in town and 18-19km/L on the open road

 

There after I found what appeared to be leaking boost hoses (surprised? I'm not...)

Used the cable tie method of sorting that out temporarily till I decide on an Intercooler Setup and do it.

Install new Coolant Temp Sensor and changed new Liqui Moly Diesel 507 Oil and new Oil Filter.

Decided while I was there added new Liqui Moly G12/13 Coolant also.

 

At this stage I was averaging 15.5-16.9 km/L around town and a whopping 22-22.5km/L on the open road.

Till a few days ago, the car dropped all the coolant. Drove for approx. 8-13kms with what I thought was no coolant.

 

Got home found the leak and fixed it. Just as well I had plenty extra coolant G12/13 bottles.

Refilled the cooling system

 

But now back down to 10-11.5km/L in town and only barely managing 16.6km/L on the open road

So the Hunt begins yet again to get the mileage back up to what it should be.

[Crl123]

I have toyo proxes tr on it just got fitted last week brakes aren't binding got to be a sensor fault somewhere just unsure what it is unless it's something much more than reset my trip and 325 miles with 10 miles left in tank

[sepulchrave]

I have toyo proxes tr on it just got fitted last week brakes aren't binding got to be a sensor fault somewhere just unsure what it is unless it's something much more than reset my trip and 325 miles with 10 miles left in tank

 

ECT and MAF are the most likely candidates. Also those tyres are horrid since it's about to start raining and not stop until next April so do be careful.

[Yaris]

Uniroyal Rainsport 3s are great for wet winters

[coskev]

So the place that remapped it did it without running a diagnostic test before hand?

Says it all really, just after the easy money of banging on a generic map :(

Edited 8 November, 2016 by coskev

[Crl123]

##!!##h mapped it they could only find the cam sensor fault, they have mapped the maf out as mine was no good

[sepulchrave]

##!!##h mapped it they could only find the cam sensor fault, they have mapped the maf out as mine was no good

 

No MAF means bad fuel economy as a rule and the ECT sensor is probably no good either but that can't be mapped out so you could try replacing it instead.

[Crl123]

What is the ect?

[faboka vrs]

Engine coolant temperature sensor.

ASZ engines use the MAF sensor for the smoke map. So the ecu won't injector X fuel if it thinks theirs not enough fuel to burn it.

BLT engines use the MAP sensor for the smoke map. So the ecu won't injector X fuel if it thinks their not enough boost (so air) to burn it.

After remapping it you have no idea how these are setup. Both methods IF done well won't have a negative impact on mpg.

[faboka vrs]

Fuel sensor is also another to look at. The ecu has a map to increaae duration (think petrol duty cycle) depending on fuel temp. This is how the cheap resistor mode works.

[GLIDN]

surprise, surprise.....

Found yet more intercooler hoses leaking yesterday. While installing new rear swaybar and powerflex dogbone mount.

 

Will report back later on this week if it made a difference or not.

[vindaloo]

I've tried typing sensible things in but keep deleting them. I don't know what to start with the OP's car.

Logging via VCDS might be one thing.... Boost pressure and the fuelly ones.

[wilsonian]

Have to say it might be the way you drive. I do around 50 miles a day and get around the same 320 to a tank (to the light popping on). I know I know I have a heavy foot. If I do a cruise control M'day drive I can get over 420 to a tank - I might have a slight boost leak - not sure but the car is standard except for the 17" with 40 v12's fitted.

[Tuftythesquirrel]

I agree you should check all the intercooler hoses and bayonet seals. Mine went down 10mpg and occasionally smoked, even on a light throttle. Don't assume because the bayonet fitting is tight it is sealing OK. I've seen the O rings get pushed out of their slot and slide down the outside of the bayonet, jamming on the securing lugs.