Black soot

[Zakarados]

running stock castrol oil. I was going to change it at 7500km, but they want to do a consumption test, so I will wait for those results. Oil and Filter waiting at home.

[prcurrie]

Was told today that you get more soot on the back if you drive like Miss Daisy as it doesn't get a chance to get blown away. Cause the cars are meant to be driven hard, if you do push them a little more then the soot should be less

[Zakarados]

Was told today that you get more soot on the back if you drive like Miss Daisy as it doesn't get a chance to get blown away. Cause the cars are meant to be driven hard, if you do push them a little more then the soot should be less

I find that the harder I push, the bigger the chunks.

[bigaxe]

had the injectors replaced on monday, followed it home no black smoke washed car on tuesday, No black soot on rear of car and it has been driven all week about 25ks a day, soot would previously appear after about a 10k drive. Soot would leave a dusty residue on your finger when you wipe the back of car definately not oily. Soot appeared on rear of car from the first day we picked it up, and yes it does use oil, so far 3l at 6000ks

[gavs]

had the injectors replaced on monday, followed it home no black smoke washed car on tuesday, No black soot on rear of car and it has been driven all week about 25ks a day, soot would previously appear after about a 10k drive. Soot would leave a dusty residue on your finger when you wipe the back of car definately not oily. Soot appeared on rear of car from the first day we picked it up, and yes it does use oil, so far 3l at 6000ks

No surprise really. It's not the first time VW have had issues with fuel injectors, on diesel or petrol.

[gavs]

Was told today that you get more soot on the back if you drive like Miss Daisy as it doesn't get a chance to get blown away. Cause the cars are meant to be driven hard, if you do push them a little more then the soot should be less

I don't believe this at all. It's not like there is a particulate filter like a diesel that needs to burn off! If there is soot, then particle matter is being generated, no matter how hard it's being driven. Also the faster you go in a hatchback, the worse the vacuum at the rear of the car so you would see more soot on the rear of the car as the surrounding air is displaced, I would think with my basic levels of aerodynamic knowledge that this would also apply to heavy acceleration.

Coming from a diesel background, ive spent a little time inside the worshops of diesel mechanics. The black smoke you see being belched out of diesels is basically a cloud of soot. that there is a good example.
This generally occurs because the injectors aren't firing the fuel into the combustion chamber as well as they should, particularly prevalent in older diesels. Once a set of injectors reaches about 100,000kms they are dribbling fuel into the combustion chamber, not spraying it into an atomized fume as they should. This results (in simple terms) in partial combustion which instead of vapourising the fuel atoms, it ends up just scorching the molecules instead which then appear as soot as they exit the exhaust.

[car_nut]

I am a fairly new owner (done just over 1000 ks) and have noticed this black soot from new (white car). It's not bad enough to annoy me at this stage and I love the car.

In my previous profession I was somewhat of a particle fallout 'specialist'. I examined the 'soot' from my car under a microscope and I can confirm that it is typical to the emissions from all motor vehicles albeit in much greater proportions from my GTI. There is certainly no evidence of oil. My oil level has gone down just under 2mm on the dip stick from new and I still don't know if my motor is going to be one of the excessive oil burners.

Do other petrol turbos eg Subaru WRX emit this soot in similar proportions to the Polo GTI?

[Yaks1974]

My wife has a forester XT, same engine as WRX. Done 70000km the tailpipe is as clean as the day we bought it, no kidding!
It has not burned an ounce of oil either!

[nomadx38]

Well someone must be snorting up the carbon dust everytime you get home becuase there isn't a SINGLE car in the world which won't create black smoke which by the way is carbon - funny enough its the byproduct of burning fossil fuels...who knew?

And I got a mate at work with a my12 WRX premium and regardless of what gear he is in 1-2000rpm will always bellow a cloud of soot!

Short answer yes, all cars emit soot just some more than others. I know the WRX has the same smoke cloud as a GTI so dont feel bad. it's a normal part of the combustion depending how they have set the timing for the ignition.

As for the GTI it runs rich on take off (it is assumed this is to prevent pinging) and leaner up high.

The oil on the other hand is a separate problem...

[kaanage]

Well someone must be snorting up the carbon dust everytime you get home becuase there isn't a SINGLE car in the world which won't create black smoke which by the way is carbon - funny enough its the byproduct of burning fossil fuels...who knew?

Easy, mate. If a car burns all of it's fuel completely (or the cat finishes off anything that is partially burnt), then the carbon will be released as C02 and no deposits will be left in the exhaust system. It is possible - some diesels with urea (Adblue) injection have incredibly clean tail pipes.