AOS, black exhaust, oil consumption

[hummitz]

Wondering if someone can help explain the color of my exhaust?

My 2003 C4S (just passed 30,000 km or 18,600 mi) is creeping up to 1L per 600 - 700 km and seems to be worse when driven hard. I had someone follow me to check out the exhaust and appartently I look like a diesel (black exhaust) when stepping on it from start (espescially out the left side).

After doing some research through this forum (which has been very helpful), it looks like the first place to start would be the AOS. This makes sense to me but I would have expected my exhaust to be blue if it was burning oil. Could the black exhaust be a faulty sensor (due to oil bypass through AOS maybe) making things too rich? Any comments are greatly appreciated and thanks in advance!

[Loren]

In most case you will get a CEl if the mixture is too rich.

You can check the throttle body for oil if you suspect the AOS.

[RFM]

I could be wrong, but i do not trust the cylinder bank 1 (right side) efficiency, given the different exhaust color left and right and the excessive oil consumption. Let check the compression and do a cyl. leak test to be sure.

[phillipj]

A bad AOS tends to produce huge clouds of white smoke not black. Kind of like "007 getting away from bad guys" amount of smoke..

[PAULSPEED]

I run about 5 gallons of racing gas to clean the tops

of the pistons. Then I would check the exhaust again.

The compression test is the best. It is alot of work

because the spark plugs are so deep seated.

Paul

[Jon996]

FYI, I had compression and leakdown tests performed at the dealer for $350.