Black soot

[gavs]

Black soot

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.

[Yaks1974]

I never said the car doesn't produce black smoke when you gun it, it does. All I said is that after 70k the exhaust tips are clean as and the boxer still has not chewed an ounce of oil.

[nomadx38]

Oh granted cars have become very efficient compared to the older days and more or less completely burn the fuel to create very few emissions, but every car will still create soot (whether by revving it hard or just by design) and to say you don't have any carbon what so ever in your exahust after 70,000km is a bit bs - especially when were talking about a WRX motor that chuffs like a steam engine

[Yaks1974]

No BS dude, the chrome tips are clean as, if I wipe my finger inside the pipe I get very,very little carbon. Looking at the inside of the pipe you can make out the colour of the metal with no carbon residue. The GTI on the other hand can get a layer of black carbon inside the pipe and on the tips if driven in D mode after a day, much less in M mode. I'm happy to provide pics if u still insist I'm BSing. I will say this though it is driven very sedately by the wife as the primary driver it is only ever given a bit of stick by me on the rare occasion that I get to drive it, if that makes a difference.

[car_nut]

Oh granted cars have become very efficient compared to the older days and more or less completely burn the fuel to create very few emissions, but every car will still create soot (whether by revving it hard or just by design) and to say you don't have any carbon what so ever in your exahust after 70,000km is a bit bs - especially when were talking about a WRX motor that chuffs like a steam engine

Agree and thank you for all your comments. I checked the exhaust pipe of my wife's newish and incredibly efficient Honda Jazz VTI-s and it is quite sooty.

[noone]

I think its silly to say all cars do it, I've watched 69 AMG's take off crazily quick and smokeless, I have never seen much on the boot of my car that isn't dust (they do dust up quickly) and the old-skool 1.8T in the old Polo GTI is from the 90's (in its original flavour). Putting down a bit more kw and torque (happy to be challenged on that) than the 6R, so possibly an issue or design (to do with the twin-charger design, tiny engine or DSG)

Yes, you run a richer mixture at higher revs to protect the engine, but then you are getting away from the best performance from the Stoichiometric ratio, so its not the best for the environment or performance.

When I hear about a 6R GTI burning through oil there seems to be a number of fixes, so I'd assume one of those will help.

[Zakarados]

Heavy sooting/oil chunks on the hatch on the Polo GTi is not normal. After having my engine rebuilt, there is no soot at all. 1500km in and no chunks to be seen. I am also getting no oil consumption so I assume they are related.

[tj9630]

I did a clean and after a week it turns to this! around 800kms clocked up so far...



you can see where i wiped alot of soot with the finger...




I read that for one person it has slowly resolved so thats what im hoping for, not much oil use, still near the top after 1000kms