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Author Topic: Black specks on rear of the car  (Read 1778 times)

Offline Dave_d

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Black specks on rear of the car
« on: July 17, 2017, 05:29:19 pm »
Hi guys, any ideas why I get black specks on the rear of my car all the time?

Offline stealthwolf

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Re: Black specks on rear of the car
« Reply #1 on: July 17, 2017, 05:35:45 pm »
Probably because it's a hatchback.
Photos?

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Offline Juliand

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Re: Black specks on rear of the car
« Reply #2 on: July 17, 2017, 05:36:07 pm »
Oil or carbon (both?) from exhaust? Or does another car park reversed up against you?

willni

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Re: Black specks on rear of the car
« Reply #3 on: July 17, 2017, 06:14:10 pm »
If they're above the exhaust about 30cm either side of the exhaust then it's carbon from running rich.
If they're everywhere it's the road and it's tar, more common on recently tarred roads

Offline AJP

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Re: Black specks on rear of the car
« Reply #4 on: July 17, 2017, 08:01:02 pm »
If they're above the exhaust about 30cm either side of the exhaust then it's carbon from running rich.
If they're everywhere it's the road and it's tar, more common on recently tarred roads
Yes and no.

Yes, it's from the exhaust. But it doesn't necessarily mean it's running rich. I suppose you could apply that rule in general - as in across all cars - but TFSIs really do spit some crap out, even when healthy, and especially when tuned.

Offline lukemk5gti

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Re: Black specks on rear of the car
« Reply #5 on: July 18, 2017, 08:39:41 am »
Did you recently drive over fresh road works?

Probably tar if they're sticky but able to be picked off with your finger.

Offline Dave_d

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Re: Black specks on rear of the car
« Reply #6 on: July 18, 2017, 09:27:59 am »
Thanks for all your replies, I'd hazard a guess at it being carbon as it's very easily wiped away with a cloth / finger. No idea if this cars been mapped or not. It has a cobra back box section on it though. Any guesses as to why it is running rich?

willni

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Re: Black specks on rear of the car
« Reply #7 on: July 18, 2017, 10:04:00 am »
Thanks for all your replies, I'd hazard a guess at it being carbon as it's very easily wiped away with a cloth / finger. No idea if this cars been mapped or not. It has a cobra back box section on it though. Any guesses as to why it is running rich?

If it's carbon it's really just too much fuel in the air/fuel mixture, could be a faulty oxygen sensor happened to my brother then the engine light came on a few months later on because it's running rich from the above sensor, so don't worry about that if it pops up.

Are the inside of the exhaust tips very very black? this helps tell it's carbon. If they are clean the inside and see how long it takes for them to get back to that state if it's a week it's running rich, not a definitive test though.

Offline pudding

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Re: Black specks on rear of the car
« Reply #8 on: July 18, 2017, 10:23:24 am »
Aftermarket exhaust is my guess!

You'll get a lot more soot coming through a 'straight through' system compared to the baffled factory system.

Mine is stage 1 tuned with the factory catback and I don't have any sooty klingons on my bumper  :smiley:


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Offline Dave_d

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Re: Black specks on rear of the car
« Reply #9 on: July 18, 2017, 12:18:06 pm »
Thanks for all your replies, I'd hazard a guess at it being carbon as it's very easily wiped away with a cloth / finger. No idea if this cars been mapped or not. It has a cobra back box section on it though. Any guesses as to why it is running rich?

If it's carbon it's really just too much fuel in the air/fuel mixture, could be a faulty oxygen sensor happened to my brother then the engine light came on a few months later on because it's running rich from the above sensor, so don't worry about that if it pops up.

Are the inside of the exhaust tips very very black? this helps tell it's carbon. If they are clean the inside and see how long it takes for them to get back to that state if it's a week it's running rich, not a definitive test though.

Yeah, the inside of the exhaust tips are very black. I shall give them a clean, you guys have made me feel much better about the engine. This being my first turbocharged petrol it's all new to me.