Hi all, my fuel economy has dropped dramatically in this last week, and have so far exhausted my list of things to check...so am looking for any other ideas!!

My car is as follows:

 

 

Superb 1.9TDI (AWX) engine

Recently Terracleaned (running sweetly afterwards by the way)

K&N panel filter, CCV Catch can mod, EGR delete, Stage 1 Remap (local company), and always run on V-Power Nitro+, tyres are all new and at the correct pressure

 

Last week on my 20mile run to work it was achieving around 54MPG, this week it has dropped down to around 44MPG L

I am wondering whether the winter additives have now been added to fuel so this is an expected and undesirable side effect….

 

The MAF has been cleaned using electrical contact cleaner, but MPG has not improved since

 

Cheers

Adam

Stuck VNT vanes?  May not be related, but if the remap is not done right to compensate for elevated boost, what can happen is that the VNT actuator goes extreme and can jam up.

Some people have used Mr Muscle oven cleaned to loosen up the carbon inside.  May be an option for you.  WInter grade diesel should not lose you 20% economy!

Thanks, I've been considering the Mr Muscle treatment and think I'll give it a try now in any case!

May not be your issue but avoid cheap supermarket diesel, i used it a few times and my MPG was terrible on it.

I have used nothing but supermarket fuel for the last 20years with no problems on any of my cars. On my mk1 I often achieved near sixty mpg to work and now on my make 2 I better that. Just my experience that's all.

I notice an MPG drop during winter too from my 1.9tdi superb, from around 52mpg down to 48mpg, though I would guess it has more to do with the lights being on more and the roads being wet than the fuel changing much?

Winter diesel is full of additives which decreases fuel economy by a lot. The reason is the additives that prevent diesel from freezing and makes it liquid even at very low temperatures. 

 

Shell V-Power diesel has additives that increase the cetane numbers. Just like petrol, high cetane will ignite diesel at a lower pressure, which increases power output. They also add a low percentage of cleaning additives that will help your fuel system keep itself clean. But like normal diesel they also have to add additives at winter which prevents freezing.

 

In summertime no additives are added to diesel, hence a lot better economy.

Oh the old supermarket diesel rubbish.

I always use supermarket diesel and I regularly see 60 mpg.

On a careful run a got 82.2 MPG from my 1.9 Superb, so I doubt supermarket diesel is the problem.

http://i36.photobucket.com/albums/e27/Alan16ac/8b0d2d18.mp4

My MAF started playing up and this caused me a great loss in MPG, maybe that could be the issue?

I notice an MPG drop during winter too from my 1.9tdi superb, from around 52mpg down to 48mpg, though I would guess it has more to do with the lights being on more and the roads being wet than the fuel changing much?

and cold and dark so more ancillaries (lights and heaters) on. I presume the economy is even more rubbish on cold starts....

Just to update, I have done the old Mr Muscle treatment and drivability has improved-it's actually remarkable what a difference this has had!

I cannot comment on economy yet as my right foot has been a little heavy enjoying the car

Isn't the EGR delete well known to increase warmup time and hence also delay engine getting up to good economy? My car loses 3-4 mpg in winter without EGR delete, could that not account for most of your loss?

jimbof- that's a good point, I had heard that too and yes it does seem to take longer to warm up on these colder days.

You really need to blank off half the radiator on the 1.9PD in Winter - the engine is so efficient that it won't fully warm up under light load unless you do. I use a heavy plastic animal feed bag, jammed in with pipe insulation at the top edge of the condenser. Blank the half covered by the engine driven fan so that the electric fan can still work. Leave the steering hydraulic fluid cooler exposed to air.

 

VAG coolant thermostats are also poor and degrade over time, opening early and closing late. Unfortunately, only the OE thermostat fits the retaining lugs in the housing. If you change the thermostat at the same time as the water pump (ie. each cambelt change) you can push it out when the housing is released. This avoids breaking the tabs.

 

rotodiesel.

Thanks rotodiesel, that sounds like a good project for the weekend- I don't suppose you have a photo of that setup?

Feck I would only get about 45mpg on my 1.9 115 bhp mk1 08

Feck I would only get about 45mpg on my 1.9 115 bhp mk1 08

Really? I'd have to try to get it that low! Even when driving as spirited as the barge allows I only see 48-50ish mpg.

..Whats the Mr. Muscle treatment lads?

..Whats the Mr. Muscle treatment lads?

 

Here ya go.....

 

http://www.briskoda.net/forums/topic/243533-the-mr-muscle-vnt-turbo-treatment-thought-we-needed-a-guide-of-sorts/

 

Gaz

Really? I'd have to try to get it that low! Even when driving as spirited as the barge allows I only see 48-50ish mpg.

Yeah but I don't want mine to run that low.had a chip in it but kept bring on fuel temp fault. But when I had that in mpg went but didnt like engine mag light being on