Black soot in tail pipes

[xxxBlakexxx]

When we were installing the SLP Cat Back, I noticed that the old tail pipes we pretty black. Is this normal? I have been running a C&L MAF Kit, so I would have expected to not be running rich. However, the car has 45k miles on it with only a few grand on the C&L.

Also, at idle, my rpms cycle from about 600 to 1200. The car wants to run around 600 but then starts to bog down and then they shoot up to 1200. Sometimes this happens more often then others.

Any ideas?

[surfbeast]

soot in the tailpipe is normal, unless were talking LOTS of soot. Unless your smoking out the tailpie it should be fine. I like to watch and smell of the exhaust periodically to see if I notice any changes in color/odor. It sounds like you may need to change or clean your IAC. My car did the same thing and I cleaned it with brake cleaner and it has run fine since. Also check all the intake/plenum conections for lose or cracked hoses.

Happy Easter!

[xxxBlakexxx]

Surfbeat, by "IAC" I assume you are referring to the flow sensor wires in the MAF, correct? I am not familiar with what IAC stands for.

Thanks for the comments.

[surfbeast]

The IAC is the part that is on the upper plenum toward the front of the engine. The black hose with the black box that runs from the intake tube connects into it. It looks like a small cylinder , a connector plugs into it and the unit is bolted into the upper plenum. If the car is running and you remove the black hose from the IAC the car dies. You can unbolt the IAC and remove it from the plenum, squirt some cleaner into it and let it dry. Put it back on and see if that helps. Hope this works and isn't to confussing.
You could also try cleaning the MAF sensor.

IAC = Idel Air Control

[91LX2Bfast]

Black soot is normal. You are burning a fuel.

[xxxBlakexxx]

Roger that!!!

[explicitone]

Originally posted by 91LX2Bfast
Black soot is normal. You are burning a fuel.

I 2nd

[xxxBlakexxx]

I need to get the IAC cleaned soon. I picked up some cleaner today as the car actually died on me one time today slowing for a light. The rpms will drop real low at times at idle and apparently low enough to stall.

Just to be sure, the IAC is bolted to my upper plenum correct? There are two bolts. It looks like a small flying saucer. There is a very small tube on top that pulls right off. Can I squirt the cleaner in the top when the tube is removed? or do I need to remove the entire IAC? If so, where to I inject the cleaner?

There is a larger tube connected in the back. I assume this is the exhaust line return the exhaust to the plenum when it is needed. I assume that the car is gulping for air because the "plunger" in the IAC is not being allowed to open completely.

Can I screw this up in any way?

Thanks!