fuel saving tips

[zakkaz]

Further to my gas guzzling a4 2.0tdi avant 170 '57 94k. New- oil/filter, fuel filter, air filter, Maf sensor, very light foot, 65/70mph and only doing 36mpg motorway driving only. Are there any other things I could try to get better fuel consumption. Has anyone tried the k&n air filter? would it be worth the £50 cost? I have been told about magnets on the fuel pipes and a high performance fuel filter or is this all hot air?

[rojdag]

magnets are absolute rubbish and dont work, generally with stuff like that if it sounds too good to be true it is. High performance filter or not will not give you better MPG. Your figures sound very low though my petrol does that on the motorway:confused:

Try emptying your boot of stuff if there is any and make sure your tyres are fully inflated.

[keemaklan]

I like to run well above the recommended tyre pressures stated by Audi, but only slightly below the maximum TYRE recommended pressure. For example, Audi state 42 PSI i think at the front and rear. My tyres state a maximum of 50-something psi in the tyres, so i put in around 46-48 PSI from cold. The tyres maximum is still well under how much the tyre could really put up with, due to health and safety nonsense so nothing to worry about in all honesty.

Please dont slate me for this, i know the dangers of running high pressures!

Change gear before 2,500 rpm, accelerate not too slow but not fast either. Engine break as much as possible by just easing off the 'go fast' pedal. NEVER LABOUR THE ENGINE!

36 mpg is disgraceful! No 170 should get anything like that on a eco run. Have you ran any injector cleaner through it etc? Dont bother with the K&N filter, barely any difference, especially not in MPG anyway!

[darich]

do you have a roof rack?
checked your brakes for binding?
checked hand brake for full release?
(admittedly, brakes issues would cause heat and burning smell but worth checking)
had all tracking and alignment checked?

Tyre pressures are obviously too high but wouldn't cause low fuel consumption. don't you wear the tyres very quickly in the centre of the tread?

[zakkaz]

I had the x2 new front tyres fitted at kwik fit a couple of weeks ago so you would presume they know the correct pressure, I have just checked them and they are on 30psi. The manual says 235/40/18 should be on 35psi so I will see if that helps.

[James05]

I had the x2 new front tyres fitted at kwik fit a couple of weeks ago so you would presume they know the correct pressure, I have just checked them and they are on 30psi. The manual says 235/40/18 should be on 35psi so I will see if that helps.


You might find your steering feels better as well once you get them up to 35psi....
Never presume anything with KwikFit...did they use a torque wrench to do your wheel bolts up or did they just rattle them up with the air gun ?

Don't bother with the K&N filter, total waste of time and money if my experience with my previous car was anything to go by.

Something else to consider - what brand of diesel do you use ? Now I *know* it all comes from the same tap at the refinery..etc etc, but in my experience with my previous car ( a diesel focus) it would run fine on most diesel, but was terrible on Tesco diesel. It would smoke heavily and sounded like someone was rattling a bag of spanners under the bonnet and the tank by tank mpg dropped.
Obviously there will be people out there with differing views to me, but maybe thats something to consider ? run a couple of tanks from one brand and see how it goes ?

James

[allanmb]

NEVER LABOUR THE ENGINE! !

Why? (In the context of fuel economy)?

[zakkaz]

Thanks James, the next time I fill up I will try BP, I have been using sainsburys but I suspect that is no different from Tesco. As for kwikfit your right, when I went to collect the car one of the bolt caps was missing, when I pointed this out I was told "it was not there when I brought the car in". No way of proving it. it probably fell down a grid and he could not be bothered picking it up. I have also had the car remapped and it also has a new turbo, whats annoying is its doing 30/32mpg combined but 36mpg motorway only, I just hope the correct pressures bump it up.

[mkc]

Ive been getting 48mpg out of a 2.0 Petrol B6. Sat doing 60 drafting behind HGVs on the M4. I started off this morning with 280miles left in the tank, drove for 40 miles and now the Computer says 310 miles left! Of course it cuold be faulty but I reset before each trip. Im very happy as its twice as good as my B8 1.8T 160......

[keemaklan]

Why? (In the context of fuel economy)?

Tell me if im wrong, but as far as labouring the engine in relation to mpg is concerned, if you labour the engine you put major stress on the engine flywheel to keep the engine ''alive''. Whilst the flywheel keeps the crankshaft turning, it will gradually loose power and rpm unless on a normal straight road but even so, the driver will just put their foot down rather than downshift. Putting your foot down in a labouring car rather than downshifting tells the EDCU to inject a lot more fuel than downshifting and using higher RPMS would usually use. This is why a labouring car (diesel) usually smokes a LOT, because of the unburnt fuel coming out the exhaust. It is cheaper to downshift, rev the nuts of it than to labour the engine.

So basically, your on your bike, cycling up a slight incline in 5th gear. Your legs are starting to burn and your feeling the pain in your legs. Rather than change gear on your cycle and then just peddle a little faster, you decide to use your hands to push down on your legs to get up the hill. Using your hands is like flooding the combustion chamber with lots and lots more fuel to keep your bicycle wheels moving. Hope i explained this well enough.

This is not to mention the damage labouring does to bearings, clutch/flywheel and bottom end bearings etc with very low oil pressures due to low rpm. This is particularly important with PD engines.

I believe this to be correct!

[keemaklan]

Sorry for the double post, but i can second the use of premium fuel such as Shell V power diesel or BP ultimate diesel. Expensive but the car runs better on it and gets better MPG!

All the derv-heads on UK-MKIV.com forum swear by the use of Millers diesel addative in their car for better economy etc...

[rojdag]

If youve had it re-mapped for more power that wont help your consumption.

[zakkaz]

sorry I do not understand when you say "labouring the engine". Filled the car, drove to the lakes at 5am on a saturday morning, no traffic, M60-M61-M6 no stops, 70/75mph 6th gear, 80 miles on and then refueled- result 36mpg :confused:

[roadiescot]

buy a micra????

:D

[zakkaz]

ha ha, would buy a micra but x3 adults + walking kit + very energetic collie = disaster :o

[rojdag]

sorry I do not understand when you say "labouring the engine". Filled the car, drove to the lakes at 5am on a saturday morning, no traffic, M60-M61-M6 no stops, 70/75mph 6th gear, 80 miles on and then refueled- result 36mpg :confused:

driving in too higher gear with very low revs, which your not if your at 70/6th gear

[zakkaz]

I think it may be best if I just work harder and increase my prices :approve:

[keemaklan]

70 in 6th gear is not labouring the engine, unless you've got 5 people in the car going up a hill, in which case the engine might start labouring a bit. The engine will start to shudder and sound like its about to die when its laburing too.

There seems to be a much bigger problem with your car than just how your driving it or incorrect tyre pressures etc. I would suggest you take it for a italian tune up. It certainly made my car feel better!

Diesels need to be worked hard, under good load to do a italian tune up otherwise not enough heat is produced to clean out the engine of carbon deposits etc. Fill the car with lots of heavy stuff or people, find a good long steep hill somewhere on a motorway such as near Dover (some amazingly steep hills there!!) and then give it the booting off its life.

Some people swear they see 'sparks' flying out of the exhaust doing it on their dervs, because of all the really hot carbon deposits coming out!

[Mr-Rob]

Guys,

just a word of warning when filling up at a BP garage.

Ensure you definately have the right pump.

The ultimate deisel and petrol are so a like.

I put around 10 litres of petrol in my car by mistake !!

[keemaklan]

LOL....and use your damn nectar card!!!

[zakkaz]

I will try that, but bear in mind I did give it some stick, after leaving the motorway at kendal we went across the wrynose pass and then the harknott pass (2nd highest in britain) To negotiate the Hardknott it requires 1st gear and very hard driving, your lucky if you can get into second, it is one hairpin after another. I would recommend it to anyone who likes to give there car a bit of stick and it is not for the faint hearted as there are no armco barriers so if you leave the road its ta ta.

[keemaklan]

Please, GO ON. Dont stop! Where is this paradise on earth? How do i get there!?

[zakkaz]

Take jct36a follow the signs for Windermere, then to Ambleside, A593 towards coniston, watch for signs pointing right to little langdale then follow signs for cockley beck, wrynose pass and then the dreaded hardknott, best do it when its quite and with a passenger to scan the road ahead as it requires 100% concentration on the road, then you can really put your foot down. Some of the gradients are 1:3 so at some points you can not see what is approaching in the opposite direction, it's great, i have done it x3 times

[bambamjj]

I will try that, but bear in mind I did give it some stick, after leaving the motorway at kendal we went across the wrynose pass and then the harknott pass (2nd highest in britain) To negotiate the Hardknott it requires 1st gear and very hard driving, your lucky if you can get into second, it is one hairpin after another. I would recommend it to anyone who likes to give there car a bit of stick and it is not for the faint hearted as there are no armco barriers so if you leave the road its ta ta.

Ive been up there several times, fantastic drive going up and down, did it 3 weeks ago in a New freelander (I work for Digital Switchover so get to some very remote places) and it still had to be worked, few hairy moments as coming down on the hairpins it would suddenly be icy and car slide quite a few times... But seriously if your a confident driver do them both and take a camera, you wont regret.

[zakkaz]

Before taking the previous advice and placing my order for a micra.......does anyone know if removing the dpf and having a bypass pipe fitted, would this improve economy and would it still pass its mot, if so is there anywhere in the north west that can be recommended

[keemaklan]

Removing the DPF can only be seen as a good thing to any car!

I dont know whether it will increase your fuel economy, but i would take a educated guess and say YES, slightly.

The DPF is a full wall flow filter, which means that the gases pass through one side, and are blocked at the other end of the filter, meaning the gas's have to pass through the walls of the filter. When this occurs, the NOx particles dont pass through the filter walls and are burnt off when the engine regenerates (when exhaust temperatures are high enough for regeneration). If its been quite sometime that the car has been driven and the exhaust temperatures have been consistently low that regeneration cant occur, the engine will SELF-REGENERATE, by means of dumping tons of fuel through the engine, to raise exhaust temperatures enough to burn off the NOx Particles. (This could be why you have such poor MPG!)


The byproduct of regeneration and the burning of NOx particles is ASH. This is why over time, regardless of the car being driven only on motorways or around town, the DPF will become blocked! The Ash blocks the filter! Replacement DPF's dont come cheap.

You could have a problem with your DPF, so that one of the sensors regulating the build up of backpressure in the exhaust (pressure caused by NOx particles on the filter wall not allowing gas through) is incorrectly telling your engine to add more fuel into the combustion chamber and hence the poor mpg...

Food for thought!

A) Get it removed and remapped and together you'll see 220 odd bhp iirc.

B) Diesels are only subjected to smoke tests at the moment, though i believe this to be changing, but don't worry, it'll still pass and if it doesen't, you obviously don't know a very friendly mechanic!

C) use a reputable company such as Awesome/AMD to remove and map out the DPF!

[zakkaz]

Cheers for that, but will I need to get the dpf filter removed from the exhausts inner or have a by-pass exhaust fitted as well as the remap for the cpu?

[rojdag]

220 out of a diesel :eek:

[keemaklan]

I will leave you with a little research and reading to do.

I refer you to this post:

http://uk-mkivs.net/forums/t/227301.aspx

At first, DPF removal and remapping was over £1,000. Now prices have dropped massively and it can be done for under £800 all in all.

220 bhp may be a little optimistic, though i have read it before on UK-MKIVS i believe.

MPG increase, fo sure!