[mihalich]

Anyone else notice that when you're running the a/c or heat without the recirculation on that you get an unusual amount of what smells like exhaust fumes in the car through the vents? I mean, I've smelled exhaust coming through in cold whether a little, but this seems excessive.

It is obviously especially bad when you have a car in front of you letting out a good load from the tail pipes. But i have noticed it right when I start the car up in the driveway. Before I have to chance to hit the recirculation button I notice a good amount coming through.

And btw, is it too much to ask GM to remember the last state the recirculation button was in, so every time I turn the car on, I don't have to hit the button? I have not seen one GM car ever do this.

Joe

 

[mihalich]

OK, I think I know what may be causing this. While on my road trip this weekend, I happened to notice that the inside of the tailpipes on this thing are totally black. Looks like a good thick coating of buildup in there. Now, I know it is normal for it to be somewhat black in there as you put lots of miles on the car. But this car only has 2800 miles on it.

The black in the tailpipe along with the fuel/exhaust smell lead me to believe that this thing may be running a little or a lot on the rich side...using too much fuel. These would be symptoms of that. Ultimately if this goes on long enough, it could clog up the catalytic converter...which also could explain the faint converter egg smells I've had. I can't prove though if those smells were me or someone in front of me.

I'm about due for my first oil change, and I'm going to have the dealer look into that.

Out of curiosity, I'm wondering if anyone else has large buildups of black stuff in their tailpipe(s). And if so, how many miles do you have?

Thanks,
Joe

 

[copperbeech]

I happened to notice that the inside of the tailpipes on this thing are totally black. Looks like a good thick coating of buildup in there. Now, I know it is normal for it to be somewhat black in there as you put lots of miles on the car.

I am not sure this needs to be the case. I have a 4 year old Vibe with almost 50k miles and one could almost eat off the end of the tailpipe . It is stainless steel spotless.

The black in the tailpipe along with the fuel/exhaust smell lead me to believe that this thing may be running a little or a lot on the rich side...using too much fuel.

For sure I am know car expert...not even close *but* if what you say is true this is typical of the DI version of the engine...is yours the 09...and even a regular VVT engine shows this fuel dilution.

I'm about due for my first oil change, and I'm going to have the dealer look into that.

Ah ha! Joe, if at all possible take a sample of your oil when you change it out. The specifics of fuel in the oil can be easily verified by a Used Oil Analysis (UOA). We need more of this data...especially for the 09 DI edition of this VVT.

i.e.

http://www.acadiaforum.net/forum/index.php?topic=4011.0 AND/OR

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1425453&fpart=1 AND/OR

http://www.enclaveforum.net/index.php?topic=4222.60 (start at Reply # 67)

 

[rbarrios]

I saw a Traverse in front of me. It was a California Edition Traverse... (LT trim with duals, and 20 inch rims) and I did in fact notice that the exhuast pipes were coated in black...... I thought it was odd.. since my Trailblazers tip is very very clean at 143,000.

 

[stumpk]

The inside of my pipes are black on my LTZ, which makes sense to me. It's called an exhaust for a reason...its gonna get black. My LTZ now has 8000k on it.

 

[copperbeech]

It's called an exhaust for a reason...its gonna get black.

Not necessarily. As I posted my Vibe has 48k miles and the tailpipe is stainless steel clean.

 

[rbarrios]

Im tempted to go snap a picture of the exhaust tip on my trailblazer.

 

[rbarrios]

I know what you mean about the exhaust- but there too black too soon. I see black tips on my 1970 Monte Carlo with the 350.
But that has a carb and well its 1970 technology......
But here is the exhaust pipe on my 2003 Trailblazer with the Inline 6..... I am at 142,830 miles.
I can still see the welds and where the pipe was mended toghether.... no black soot buildup
so something is different with the DI engines.

 

[mihalich]

As a comparison, here is a picture of mine. It's hard to tell how black it is, so I rubbed off a little area so it was clear, next to the black build up.

Joe

 

[rbarrios]

thanks mihalich for that picture.
sure is what im seeing on the few Traverses Ive seen.
I wonder if it has something to do with break in of the engine on a DI engine.

 

[lxc]

As a comparison, here is a picture of mine. It's hard to tell how black it is, so I rubbed off a little area so it was clear, next to the black build up.

Joe

I looked underneath my car yesterday. My exhaust pipe opening is more darker and coated with printer-toner like dust. Also on the bottom center of muffler, there is a small pin hole. The area around this pin hole is completely blackened as well.

 

[rbarrios]

yeah, the pin hole I believe is there to allow the moisture in the exhaust to condense and drip out.
If you drive long- then most of the moisture will be expelled as the exhaust system heats up and 'boils' off the moisture.