Make a donation

Author Topic: Black specks on rear of the car  (Read 1735 times)

Offline Dave_d

  • Always Involved
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 5
  • Posts: 105
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

  • Just look at my post count
  • ******
  • Thank You
  • -Given: 306
  • -Receive: 291
  • Posts: 7834
  • ED30 No.1412
    • Email
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?

The GTI isn't just a machine. It's very much a living, breathing thing.

Offline Juliand

  • Always Involved
  • ****
  • Thank You
  • -Given: 14
  • -Receive: 18
  • Posts: 358
    • Email
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

  • Guest
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

  • Global Moderator
  • Just look at my post count
  • *
  • Thank You
  • -Given: 392
  • -Receive: 316
  • Posts: 3212
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

  • Just look at my post count
  • ******
  • Thank You
  • -Given: 28
  • -Receive: 118
  • Posts: 1845
    • Email
  • My Ride: http://www.mk5golfgti.co.uk/forum/index.php/topic,89715.msg907250.html#msg907250
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

  • Always Involved
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 5
  • Posts: 105
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

  • Guest
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

  • Global Moderator
  • Just look at my post count
  • *
  • Thank You
  • -Given: 2
  • -Receive: 690
  • Posts: 8353
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:


2007 ED30 | 2009 TDI 140 | 2016 BMW 330D

Offline Dave_d

  • Always Involved
  • ****
  • Thank You
  • -Given: 12
  • -Receive: 5
  • Posts: 105
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.