my dad reached in to my tail pipe with his finger and by wat he had on his finger he said i am running rich.  i have a k&n cold air intake and a smooth bore throtle body spacer. is there anything i can do?  

check the coloring of the spark plugs to find out if you're rich.  

On a TJ?

What in the world was your dad doing sticking his finger in your tailpipe? Honestly, like that tells you anything in this day and age.

There is nothing wrong with your Jeep. It is not running rich. If it were running rich there would be a DTC and Check Engine light on alerting you to the problem. These new computer controlled engines don't run rich or lean unless there is a problem, and if there is a problem the vehicle is going to let you know about it.  

Oh, and even then, if anything having a high flow filter like the K&N is going to cause a LEAN condition, more air then fuel, not a rich condition, if that is what your dad is trying to get at...  

even if you have a computer you can still run rich or lean.  im thinking it is somthing to do with the fuel pump or the injectors, the check engine light has came on but it went off not too long ago. theres no doubt i am running rich. i know that the k&n would cause a lean effect, but i was listing my mods so everyone knows what im working with. maybe it is a clogged up injector that doesnt spray a fine mist and sprays more of a thick spray and thats why it is running rich.  i have also noticed that the jeep at idle is a little bit rough and bucks a little bit. any help would be appreciated  

The computer still will not allow it run lean to the point of having soot in the exhaust.

Thick spray vs. Fine Spray... doesn't make a difference. Think about it. I shoot you with a squirt gun filled with a gallon of water, fine spray, or I dump a gallon on you... thick spray... same amount of water.

Clogged injectors would cause the opposite, think about it, clogged injector means less fuel getting in the cylinder with the same about of air and you are lean.

Fuel pumps won't cause a rich condition, they only provide fuel for the injectors. Fuel pumps are regulated, either with a return, bypass, in the tank, or at the rail and these regulators only allow the amount of flow and pressure that the injectors need to be delivered, what ever is not used is returned to the tank. Even if you had a bad regulator and it was sending 90psi to the rail, you wouldn't end up rich, your Jeep wouldn't run worth a crap.

There are only a few things that will cause a computer controlled vehicle to go rich, a dirty Mass Airflow Sensor (computer thinks there is more air than there is so it adds more fuel), bad O2 sensor (computer can't tell there is too much fuel being burnt, so it adds more)

You're chasing a problem that doesn't exist here. If you want to know 100% for sure and prove me wrong, go get an A/F meter and see exactly what it's doing. With out doing that you are trying to fix a problem that has never been diagnosed as being a problem in the first place...  

Or like someone already said pull the plugs and read them!!  Easy... blistery white= Lean  dark black sooty maybe wet, rich or passing oil,, Light brownish clean looking..  normal.. There are many books and shop manuals that have color pictures to show you what to look for.. Tale pipes theses days look black and sooty so that is normal and means nothing.. Years ago your dad would be right..  George  

thank you george...
papa needs to wipe off that grin and explain why the black on his finger means it's rich...
maybe junior drives it with the pedal to the metal.  

well when he pulled his finger out it was a greasy type of substance not a powdery soot type, thanks for any help given.  

how would i be able to tell if i need a new o2 sensor because that is what im thinking it is from what yall are telling me.  

could be valve seals or guides,
on the other hand the greasy stuff may be just from condensation, the cat is doing it's job.  

Either have it tested like the editor said and or do us a favor and pull out a couple of plugs and take a picture of them with the cell phone (at 640x480 pixels) or whatever and post it so we can see if the rich condition shows itself, If you have trouble send the pic to my e-mail, (you can find by clicking on my screen name) and I'll put a URL to it and post them. make sure the gap is correct or no more than a couple thousandths larger than the manufactures recommended gap, check that you have the correct heat range, (hotter is not better they only create a detonation problem unless you have a majorly high mileage engine.) some parts counter people don't always give you the correct parts, they are not always gaped correctly as they come out of the box. Lets try to get rid of the arguments and figure out what or where the problem is. The plugs may be just a start but will eliminate possibilities and answer the rich question. they could help with the o2 sensor question also.  

Hi....I also have a Jeep TJ...1997 Wrangler.
The tail pipe shoots out black soot.
It is thick enough to look like spray paint on the ground.
It turns the palm of your hand black if you hold your palm on the tail pipe.

I get a MIL code of 51
which is lean being compensated by the computer to make it run rich.
I have no further clues as it runs good, has no other codes but only gets 10 mpg....I installed 2 new Oxy sensors...no help. I installed one of those cone type air cleaners and got 2mpg increase. New cap, rotor, plugs....old ones black....still no help
HELP....!  

I would suggest taking your rig to autozone and have them do a scan for you. It should be free and even though it is not always 100% accurate it gives you a good starting point. You are getting some not so hot advise from some on this forum. There is a big difference between properly atomized fuel and "pooling" fuel caused by a clogged or bad injector. A clogged injector can most certainly cause a rich condition. Some other culprits could be the IAC ( idle/air control valve)-which can be removed from the throttle body and cleaned, also possibly the throttle position sensor, O2 sensor, bad plug or wires, ETC. Go to autozone as a starting point and check/clean the plugs and IAC. Good luck -  

Thanks for the reply.
I found that the oil fill cap was causing the black  smoke.....strange but true.
I put a new gasket on it, because it seemed slightly un snug. That stopped the black stuff from coming out of the tail pipe. Then one day soon after, I had cause to floor the vehicle when entering traffic....it did fine until about 3/4 into the acccleration, then bogged slightly, then a huge pop and a really big plume of black soot and smoke out the tail pipe.....every since....no black smoke or soot.

I also got one of those OBD2 tools and a lap top computer.The free soft ware is not all that great, but it says my forward O2 sensor is putting out 0.0V with +32 fuel trim causing the rich condition.
Since it was  a new sensor, I suppose they don't all work. The wiring is good to the ecm, and the heater in the sensor is ok.
That's it for now....more after replacing the sensor.