Poor Mpg, Black smoke and have diconnected MAF

[m8gic]

First of all I like to say a big HELLO. This is my first post and only been an Audi driver for 1 week.

I bought an Audi A4 1.9 TDI 130 SE last wekend, it is an 2002 model and I had to travel 150 to collect it.

When I collected it and before the drive home I filled it up with £40 diesel as the computer was saying 55 miles left. from a local garage at 101.9 p/litre .On the drive home which consisted purely of motorway after 30 miles into the 150 mile journey the car felt gutless (i.e no pull) and was struggling for speed. When I got home and turned the car off after I let the turbo cool down and explained to my friend it was gutless, he then took it for a drive. I was in the passenger side and the car felt alive again , we could feel the turbo and the pull was great and picked up speed quickly. Then I drove the car for a few days and the 40 diesel gave 310 miles with 150 of that being mway and the rest local. I was wondering if that is decent mpg as I do not believe the computer at all.

Also I noticed a few days after that the car was smokey. The exhaust smoke was black and my wife who was driving behind me said it was black constantly. I filled it with some Shell Diesel Optimax to help cure this problem and added some redex diesel treatment. When the car is idling there is no blacksmoke.

Today,I checked the MAF sensor and unplugged it, the strange thing was that when I unplugged it, there was no difference to the car I did not drive it but the revs were constant and no change in engine sound.

Can someone please advise me if I am getting poor MPG and also if there is a problem with the MAF. If the MAF has anything to do with poor MPg or the black smoke which I believe is over fueling.

[onzarob]

The MAF maybe faulty or the vacuum control for the variable vane turbo, both straight forward fixes.

Do a search and you should find loads of info.

Also if you can get a fault code scan...will save allot of time and guess work.

Welcome to the forum:D

[m8gic]

Thank you for the reply I will do a search. Do you think the MPG is ok?

[onzarob]

On my A4 with the 110BHP engine i could get 620miles from a tank....then I had about 40 miles left on the trip display.

The 130 is slightly thirstier i would expect between 45 and 50 mpg. I calculate from your figures you getting below 40 mpg. the best way to work it out is fill it up run it then fill up again noting haow much you put in and the miles covered.

If the MAF is faulty the MPG will drop;)

[Turbokiisseli]

From my 130bhp A4 I get 740 - 760 miles a tank on the freeway and around 620 with mixed road / city.

[danclyon]

When I collected it and before the drive home I filled it up with £40 diesel as the computer was saying 55 miles left. from a local garage at 101.9 p/litre .On the drive home which consisted purely of motorway after 30 miles into the 150 mile journey the car felt gutless (i.e no pull) and was struggling for speed. When I got home and turned the car off after I let the turbo cool down and explained to my friend it was gutless, he then took it for a drive. I was in the passenger side and the car felt alive again , we could feel the turbo and the pull was great and picked up speed quickly. Then I drove the car for a few days and the 40 diesel gave 310 miles with 150 of that being mway and the rest local. I was wondering if that is decent mpg as I do not believe the computer at all.

Also I noticed a few days after that the car was smokey. The exhaust smoke was black and my wife who was driving behind me said it was black constantly. I filled it with some Shell Diesel Optimax to help cure this problem and added some redex diesel treatment. When the car is idling there is no blacksmoke.

Today,I checked the MAF sensor and unplugged it, the strange thing was that when I unplugged it, there was no difference to the car I did not drive it but the revs were constant and no change in engine sound.

Can someone please advise me if I am getting poor MPG and also if there is a problem with the MAF. If the MAF has anything to do with poor MPg or the black smoke which I believe is over fueling.

Welcome!

MPG wise that's stab in the dark calculations at low 40's (as the bottom end of my fuel guage is deffo not as linear as the top) - but I guess you went from more or less the Fuel warning light being on to somewhere about halfywa between half and 3/4 but nearer to half on £40 worth.

My car had only done 24k miles in 2yrs 10 months and was a bit sluggish when I got it - turning in the same sort of MPG and being a bit smokey to boot.

Now - 25k miles later after decent diesel (Shell VPower) - one bottle of Millers Diesel Sport 4 through it when I first owned it and 2 sets of fresh oil we now regularly get high 40's out of it - and it's the much famed Multitronic.

On a good run I can get 750+ miles out of a tank of mostly motorway. On supermarket diesel when I first got the car I'd manage 650 on a good day.

Suggest checking the EGR valve is not weeping oil - that can contribute towards a bit of smokeyness - certainly mines been less smokey since mine was changed - and my MAF is fine.

Also if it hasn't been serviced for a while - a fresh set of filters and oil can also help - especially if it's not breathing right.....if you are feeling confident a quick trip to Eurocarparts this weekend (or the dealer if you want original parts) might be a good start - but - I'd treat yourself to a bottle of Millers at Halfords and add that to the next few tankfuls which will help clean the system up a bit and go from there personally....

Cheers,
Dan.