320 miles on this tank so far, and it's just on the half full mark. I think it's looking a lot better. Maybe the gauge has gone wrong and it'll run out on 1/4 full, but other than that I'm estimating high 40s to 50 mpg on this tank, based on 260-270ish at half way being 45 mpg (6 gallons to half way approx). Not been on any long runs either. The only change has been a couple of tanks of the Miller's additive - half a bottle each time. Back last summer, I had a run back from Scotland where it was getting very juddery, and I drained a lot of water out of the water trap in the fuel filter. This was before I changed the 3rd injector as well. It improved a lot after that, but I wonder if the water has helped to gum things up. Just for clarity, the car was juddering when I bought it (it was suitably cheap), and runs better now than it ever did. A lot of the problem went away when I changed the 3rd injector, and some more when I swapped out the thermostat. Another possible explanation - one of the previous owners has been running homebrew fuel blends in it - e.g. badly treated waste veg oil, heating oil, or any number of options. This could have gummed things up a bit to the point where the Millers additive was needed to give the injectors and rings a good clean out, which is why it appears to have got me an extra 5(?) MPG? There was no sign of any problem when I had the head off though. Bores and pistons looked fine. I'm not sure how hard it would be to spot a problem with the rings though. As it stands, MPG seems to be improved, it's smoother than it's ever been at light throttle, although still not 100%. The idle is a bit smoother than it was, although still lumpy and variable.
It might be worth looking at the injector balance block in vag-com, can give an indication of whats going on. Not sure exactly which measuring block it is but just click up through them and its fairly obvious.
I'd be interested to know more about that - my assumption was that the fuel pump is trying to push the same amount of fuel to each injector. Is there an adjustment for that? Or is injector balance measuring the actual delivery to each injector? I'm in Oslo for the weekend, so I'll have a look when I'm back.
The fuel pump does just pump the same amount to each injector, but the injector balance blockjust gives an indication of how the different cylinders vary from a calculation of the acceleration of the crank at each injection event. It can show if one cylinder is very different although not the best.
So basicaly you mean it cant see subtle changes in injected quantity per injector, but it can see by way of calculation, if a cylinder is hugely behind the rest i.e a dribbling or frozen injector. Thats useful to know, change your sig to derv guru m1ke!!!
So it's more of a cylinder balance test then? Common rail engines have smooth running values that can add or take away fuel up to 1300'ish rpm to compensate for valve and or ring seal differences between cylinders
If you do have an imbalance what detrimental affect will this have? Is the fix to get the injectors balanced... Where can that be done in the UK? I am aware from previous check that my No.1 IQ is higher than the other 3...
Diesel engines cover up fueling issues very well due to the wide afr range. Petrols for obvious reasons cant and so injector faults would litraly render the car undriveable. An inbalance in a diesel car, will show up as a drop in mpg, excess smoke and difficulty to start, especialy when cold. But the carvwill otherwise appear to run ok, with ok'ish mpg, but miles better than a petrol still. Balancing should be done every 85k to keep injectors in top condition. Nozzles should also be replaced at the same time. Nozzles are very easy to change, balancing is done by shiming and needs careful flow testing before and after a deep clean. There are a few places that will do this, place closest to me is in southampton. Budget for 30 quid per injector aslong as they dont need repairing. Plus the cost of nozzles.
Yep united diesel will sort you out at a good amount and also offer cheapish performance nozzles. Don't get me wrong it will show fairly small imabalances which are correct but I wouldnt be changing my injectors or getting them balanced unless they were largely different as those small differences in the cylinder balance can be caused by any number of variables not just injectors. And yes injector balancing is the only way to sort this.
By how much is it different, on another note if anyones looking for a set of injectors to get cleaned and balanced or have new nozzles fitted to I have a set here which I no longer need. Pulled from a 75k mile caddy.
I'm wondering if a solid 'shim' the size of the nop1 spring and shim could be made to allow testing of the nop2 setting? I have access to a precision engineering company two minutes walk from my work with some very helpful guys working there
I have VCDS on order so I can look myself whats going on... I will post the IQ differences on here and hopefully I can gt some opinions if its worth getting them balanced..
