How old is the fuel filter? I'd be thinking change it, drain the can it sits in and refill with either fresh fuel or injector cleaner (lets not start that debate please). 

The fuel filter was changed in April.

I've actually got another one sat on the shelf from then too as I accidentally bought 2.

 

I suppose there is nothing to lose in putting it in.

 

I have run through a full can of Diesel Purge directly into the fuel pipes, bypassing the filter.

Edited 4 November, 20196 yr by softscoop

Did you drain out what was in the bottom of the filter housing though?

 

The other, left brain, one I'm going to suggest is get your wheel alignment checked, and make sure there's not a brake rubbing, as these can make a big difference to economy. 

Admittedly I didn't bother draining the housing when I did it.

 

I've had the wheel alignment done only a few weeks ago when I had new tyres. That was a 4 wheel laser job too.

 

Checked the temp of the brakes and wheels again this morning and after 15 min at 60mph they were stone cold.

Beware! Torsion value of zero means that it is outside of measurable limits and its very easy to do when you think you have nudged it that final little bit towards the true zero, been there done that got the T shirt, but if the fuel economy was unchanged its not likely to have moved since.

 

When I check if it shows as zero I rev the engine to close to max revs and will look to see one degree or so of retardation due to belt stretch, if it remains zero then I know that its out of limits.

 

VCDS probably shows the retardation as a +ve value, like most things the units etc dont make much sense but it should definitely not remain at zero at high revs.

So I went for a spin around the block logging group 4.

 

You can see on the attached CSV that it stays mostly at 0. It does go to -0.5 on a couple of lines though.

LOG-01-021-04F-103.CSV

Just a page of incomprehensible numbers for me, par for the course with VCDS.

 

I am sure they will mean something to someone.

After a cambelt change on my 2008 PD170, my timing was out slightly. I got a rough cold starts and reduced fuel economy, which only really became noticeable when the temperatures dropped in autumn and winter.

If the weather holds out on Saturday morning, I'm going to change the fuel filter, fill the canister with injector cleaner and adjust the timing.

 

See where we are from there.

Have you considered that a recent drop in MPG might be due to Winter Diesel now being dispensed at the pumps? It always drops MPG by quite a bit.

Nothing to do with winter diesel. I started this thread in August.

On 04/11/2019 at 10:00, softscoop said:

Admittedly I didn't bother draining the housing when I did it.

 

I've had the wheel alignment done only a few weeks ago when I had new tyres. That was a 4 wheel laser job too.

 

Checked the temp of the brakes and wheels again this morning and after 15 min at 60mph they were stone cold.

 

The filter housing also acts as a water trap, so it's worthwhile. You might be able to drain it from underneath without opening the lid.

 

 

I too had smoke on start-up in my 2.0 TDi BKD engine. Turned out to be a leaking injector. replaced it with one from ebay and all was good. However it didn't affect fuel economy that much when it was leaking. At driving speeds they fire diesel so fast/often that it really makes not a lot of difference. However I can now start the car without it fogging the street with smoke and causing acute embarrasment!

 

However, now my car is 14 years old and has done 100k miles it is not as efficient as it used to be despite 11 years of tip top maintenance with regualr oil/filter changes. Maybe when they get old they get thirsty?

So I've adjusted the cam timing.

 

Torsion value is now -0.5 on idle and moves to 0 when revving.

Sound good, remains to be seen if it makes any difference on the brim to brim consumption figures.

So here we are again.

 

After adjusting the timing the engine is definitely a little bit easier to start. The smoke on cold starts seems to have gone.

 

I had to have a broken spring replaced, and during that the ignition was left on and the battery went flat so my trip was reset. Hey ho.

 

I've reset the trip since then. Over 165 miles, trip2 on the dash showed AVG of 52.1 mpg.

I filled up and calculated it properly - actually 42.5.

It's better than it was, but still lower than I'd be expecting.

 

One thing I've noticed lately is the car never seems to get properly up to temperature, even on a long run.

 

Am I right in thinking that there is a second thermostat on the 6 speed DSG?

13 hours ago, softscoop said:

Am I right in thinking that there is a second thermostat on the 6 speed DSG?

 

Yes but I would still change the main thermostat, genuine parts are a must

Edited 21 November, 20196 yr by SuperbTWM