Black Smoke!

[jbaudi]

Hi All,

I drive the 140bhp 2.0tdi a3, 2005 and these days, I tend not to boot it everywhere cos of fuel costs, so most of the time I drive like a grandad and the car is absolutely fine.

On the few occasions where I do give it some beans though I get a huge thick black puff of smoke out the back that fills the whole road behind me!

I've heard blocked injectors can cause this... is this correct, or are there any other causes?

Thanks,
Jonathan

 

[Ash187]

I used to find that when i drive it nicely and then randomly boot it i got the same before the backbox delete... i put down to the backbox collecting all the crap while you are driving it so nicely.
Now i have the backbox deleted i dont get much black smoke at all, deffo no smoke clouds

 

[Rhyso]

You need to exercise the turbo every now and again to stop carbon deposits building up. If after you've done this you are still getting thick, black smoke you may have a boost leak somewhere

Does the car feel underpowered at all?

 

[Ash187]

Good point! I had a boost pipe come off on the weekend and the car was smoking up the road behind me... but that was because the whole pipe came off. I have replaced one of the pressure pipes off the back of the turbo on Saturday but still notice a bit of loss in power so i have just ordered 2nd pipe to replace later today. il let you know if that changes the amount of smoke i get out the rear.

 

[hades-]

ASH.
what do you get out of the backbox delete ?

 

[Ash187]

more noise, less smoke and it feels like it pulls better

 

[moag]

Sounds perfectly normal. Diesels need a good blast every now and then to clear them out especially if your always doing short journeys.

 

[jbaudi]

i do give it a boot probably once a week at least so it's not like I never give it a clear out... i'm talking quit a massive amount of smoke here, more than the normal deisel fumes you see!

i'm guessing if it were a boost leak of some kind, it would be a lot more constent even under small amounts of boost, not just foot to the floor?

I wouldn't know if it felt underpowered cos I've been used to a lot faster petrol cars before owning this one, so even if it's spot on it's still gonna feel really slow lol! From past experience of boost leaks, it doesn't feel flat or wrong in any way.

How does one achieve a backbox delete then!?

 

[Ash187]

http://www.audi-sport.net/vb/a3-s3-sportback-8p-chassis/154405-back-box-delete-2-0tdi.html

 

[Rhyso]

Depends on how big the split is. It might not become apparent until you are asking for max boost. Does sound like a split pipe rather than one having popped off. If it was the latter it would drive like a bag of ****e lol

Time to stick your head under the bonnet and the car! Look for oily residue around the connections and on the pipes as thats a good indication that you have a leak

 

[Ash187]

yh if the pipe fell off you would know! it judders and throws out all your fuel in a matter of minutes! lol

another way to check is to get the car on a ramp, take off the bottom engine cover and have a look at the black silicon pipes and see if there are any splits there and make sure all the joints are secure. the clips on these pipes are not great and over time wear away and let the pipe move about.

i think i still have a small leak in mine where one of the clips on the pipe has worn away and may be letting some air out... but that will be dealt with later tonight.

 

[jbaudi]

a split pipe would actually make sense as it does sometimes seem a little flat when I put my foot down and also a very slight judder on idol... A leak test should be a good place to start I guess!?

The back box delete looks good... how much louder is it?

 

[Ash187]

its only loud when you let your foot off the throttle as the noise is the sound of the turbo spooling. not stupid loud when you are cruising and nothing that would give you a head ache.
its got a whoo'ing noise... have a look on the thread i linked before, there is a video in there

 

[Rhyso]

a split pipe would actually make sense as it does sometimes seem a little flat when I put my foot down and also a very slight judder on idol... A leak test should be a good place to start I guess!?

The back box delete looks good... how much louder is it?

Yeah a leak test or grab someone local with VCDS to log your boost and duty cycle. Actual should match requested but equally if your duty cycle is high then the turbo is working harder to develop that boost and therefore won't live as long!

 

[timmythechef]

Rhys should know, he blew up mine

 

[flying oyster]

ive just replaced all my intercooler pipes amazing amount of wear on them totally love the car again

 

[Ash187]

So I went under the car yesterday and the passenger side intercooler pipe had some oil around the clips and upon closer inspection it would seem that the top tooth had worn away, replaced the pipe and the car is pulling lovely again... Best of all the whoo'ing noise from the turbo courtesy of the back box delete has come back nice and loud! Didn't notice it had gone quiet until last night!

 

[jbaudi]

thanks guys, i'll hopefully get to the bottom of things now! back box delete sounds mint btw