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View Full Version : Excessive black smoke A6 2.5TDI



hollo
03-07-2009, 02:40 PM
Hello ,
I wonder if anyone could give me any pointers as to where to look first ? . I'm getting way too much black somke from my 1997 A6 2.5TDI ( the last of the 5 cylinder model ) and it's the red ' I ' 140hp model . So much smoke at times that I've actualy convinced my kids that it is a James Bond car with a smoke screen kit fitted.
It used to smoke a little if I floored it ( as you would expect from an older diesel ) , but if I just accelerate from 50 to 70 you can see the black smoke billowing out from behind . I've tried a few tanks of ' better ' V-power diesel and added a container of injector clear , but it's not any better. I've also tried to see if it would stop smoking and clear out if I kept my foot down , incase it was just a build up of soot ,but there was no sign of the black smoke stopping. The car has covered 112,000 miles no not mega high mileage.
Is this a common issue , and any idea's where to start ? , air filter , breather pipe somewhere , timing , diesel pump ,turbo ?
Thanks
Mike .

chilledgibbo
06-07-2009, 10:14 PM
Hi Mike

My wife has the same type of 2.5TDi, and I have known it to drop bags of soot especially under heavy load. I've noticed a big difference though since the air and fuel filter were replaced so It could be any of those clogged filter.

shark_90
06-07-2009, 10:32 PM
Have you checked for boost leaks?

mhobson
07-07-2009, 03:27 PM
Hello,

I had one the same, AEL 140bhp 6 speed, fantastic car and so economical but especially when accelerating after a bout of economy driving any cars unfortunate enough to be behind got smothered. I spent a lot of money trying to get the problem sorted including a new set of injectors £600 and air masss meter £400, turbo checked etc. but it stayed the same, I have been told that it is just a feature of that engine, but despite the smoke I once managed to get 68.7 mpg on a long run (full tank to full tank calculated, not car computer figure). I wish I had never sold it. Now have the newer shape 2.5 tdi AFB, much poorer vehicle and rarely get over 40 mpg. My daughter has an A6 2.5 tdi AAT 115 bhp and it smokes just the same.

Regards, Michael

hollo
07-07-2009, 03:53 PM
Thanks for your reply's ,

and yes I'm think it's a great car , I'm not sure about 68.7 MPG , but I can get into the 50's on a run without trying , which I think is excellent for a large luxury car.
I'll kick off with the air and fuel filter change which is nice and cheap and easy and take it from there . I'm not overly bothered about the massive black cloud which follows me , other then I'd be truly amazed if it would get through the MOT like this , and it's due in the next couple of months.
Thanks
Mike .

mhobson
07-07-2009, 05:02 PM
Hello again,

I never had a problem with my emissions, just always make sure that the engine is up to temperature at the time of MOT, I used to give mine a blast along a dual carriageway just before the appointment time to clear out the cat and pipes. Always regularly changed all filters and oil. My best mpg was from Helston to Weston Super Mare with driver and 650 kg load and return to Helston just driver, no traffic, 60 mph maximum. Unbelievable maybe but true (always wait until no more froth in the tank when filling and check full tank to full tank, the computer can be out either way). My advice is if you have got a genuine car DON'T SELL IT! I wish I had never sold mine.

Regards,

Michael

Halfcat
10-07-2009, 01:30 PM
My 2001 1.9, 130 bhp had lost power. Independent Audi dealer plugged in the laptop and diagnosed faulty air mass meter. Independent garage told me that faults with air mass meter cna result is significnatly reduced mpg, significantly increased mpg, erratic mpg or no change (covering all bases!). This was replaced by the dealer, and power was restored. Think I went from 650 miles per tank up to 700.


Unfortunately, this was about a 2 months ago (and about 4000miles) and I now have LOTS of black smoke. Oil level is high, but I think not overfilled.

Halfcat
10-07-2009, 01:31 PM
ps i have also noticed a "whistling" noise when i accelerate, if I have the window down??

Halfcat
10-07-2009, 01:34 PM
pps Garage indicated that it was generally "bad" if the faulty air mass meter was giving unusually high mpg. Think it was some kind of engine damage (altered burning /temperature??) that they indicated, but cant quite remember now.

Sorry, all this should have been one post, will think before I click!

chilledgibbo
10-07-2009, 04:25 PM
I think we just have to like with the fact that this car smokes like a Cuban! :D

Apologies for the slight digression, but I've just got ours checked out because it was starting to run sluggish especially trying to accelerate up hill, even in lower gears. Our local mechanic thought 'MAF' but then found out the Diesel pump which is getting on a bit needed a bit of reprogramming - i dare say to increase pump pressure to where it was again. Goes like a train now!

jubbly
01-12-2009, 03:22 PM
How bad is the smoking? These cars do smoke on hard acceleration but you shouldn't be like James Bond :)

The bigest cause of excessive smoking is a boost leak, check the pipe at the front left of the engine bay down to the intercooler see if there is any splits or holes in it.

Mafs are not really a problem on this car as they are a flap controled version not the hotwire type in the later cars.

Also diesel pump timing will cause smoking, the pump belt may have been changed and some garages just reset so the car will start and don't actually set the timing properly.

Duffelcoat
01-12-2009, 04:16 PM
The car isnt especially high mileage, so I would suggest that something is wrong somewhere, when they get north of 150k miles the injectors can start falling apart causing an uneven spray pattern and smoking... The lowest mileage tdi I have seen this on was £160k.

BTW Redex wont cure injectors that are falling apart, they need replacing or rebuilding, not cheap probably £400