Soot in the tail pipe = Oil burning?

[Dominik]

Hello,
This may be a simple question but it really puzzles me. I Istuck my finger in the tail pipe of my 2003 4 cyl Altima ( 88,000 km) and I found a really thick black soot, did the same with my '95 Saab 2.3L 4 cyl (211,000 km) and there was a lot less soot my finger was barely black.
Now both cars do not burn much oil Altima needs about 0.25 l top-up between 6,000 km oil changes the Saab the same, none of the cars smoke wheter during morning starup or under heavy acceleration. Could this mean heavy carbon deposits in the combution chamber and on the valves? I was considering Bardhal's "No Smoke" combustion chamber cleaner, it claims to clean carbon of the valves and combustion chambers, is this stuff any good??
I am affraid that it may affect the cat (it' just been replaced during recal service)
Would synthetic oil help here? the Altima gets Dealer service oil and when I change it Pennzoil 10w30 dino or Havoline Synthetic 5W-40 from my old stock.

 

[TheLoneRanger]

Soot in the tailpipe can also indicate a rich condition. Since it dosen't use (that much) oil, I'd look at the O2 sensors as maybe being 'lazy' or having a slow response, and contributing to the rich condition.....

 

[sanitarium16]

my pipes were clean until i ditched my catalytic converters. Now they're caked with soot!

 

[frankiee]

I wonder if that new cat has the same backpressure that the car was designed for.
Get the vacuum gauge out.


For continuously lean O2 sensor readings:

From:
http://www.kemparts.com/TechTalk/tt07.asp

For continuously lean O2 sensor readings:

1. Check sensor output wire for possible grounding. A ground will cause a false lean signal.

2. Check the MAP sensor for proper vacuum to voltage output. A high vacuum signal will cause a lean ecu reaction. (Don't forget to check manifold vacuum first!)

Check the MAP sensor for proper vacuum to voltage output. A high vacuum signal will cause a lean ecu reaction. (Don't forget to check manifold vacuum first!)

 

[Matt_S]

If the cat was just replaced, I think it's most likely that the old one wasn't heating up enough to burn off the excess hydrocarbons, so they collected on the tailpipe. If this were my car, I'd clean it out and see if it comes back. If it does, I'd look at the O2 sensors, MAP and MAF sensors.

 

[Schmoe]

I got some of that going on with my 02 Accord. Not burning a drop of oil and still getting about 27 mpg. If it ain't broke, I ain't fixing it.

 

[Greaser]

Four years ago I installed a Borla cat-back system on my 1999 Cherokee with the straight six engine.Six months into the switch my tip was black enough to use the soot for night field training camo.Have been E tested twice so far in four years,switched to HDEO Esso XD-3, and my readings are going DOWN...plugs are a slight white/grey and uses NO oil...so you tell me what the soot means

[ August 29, 2005, 12:50 PM: Message edited by: Greaser ]

 

[JTK]

That's funny. Every vehicle I've ever owned produced some soot at the end of the T-pipe. My brother's beat up gas hog 1994 F150 with the inline 4.9L 6cyl always has a shiny clean tailpipe, like it was never used

My thinking was that baby produced enough water vapor to wash out the carbon. Dunno

.
G/luck
Joel

 

[newfordrichy]

Soot in the tailpipe almost always mean that the fuel/air mixture is too rich.