black smoke help!!!!!

ive noticed black smoke coming out of my muffler so i thought it might be a bad 02 sensor making my car run too rich so i decided to put a new 02 sensor in and its still doing the same thing, when i pulled to old one out i noticed that it was covered it black carbon shit. when i replaced my sensor should i have reset my ecu as well? there is also a muffled popping sound coming from my muffler as well does that have anything to do with the black smoke?

what type engine, how many miles on it and have you ever adding cleaner to clean off carbon deposits in the head... you're on the right track as far as the black smoke being from excess fuel... what type of mods do you have to the car that would effect the air fuel mixture and do you have anything done to effect either the valve timing or ignition timing?

i have a d series engine with about 195,000km on it. d series cause i live over in japan, no mods except for a cold air intake but its been doing this before i did that, no cleaner for the head, the only other thing that ive noticed was my distributor was leaking a small amount of oil from with inside.

well if you had carbon deposits on the old O2 you might try adding some carbon cleaner to clean off the valves and see if that helps the situation... if it doesn't then you might try looking at the fuel system, ie, a leaky injector or something else.

whats this stuff called? you add it to the oil?

there are a bunch of products out there, you can go to a local parts store and they should have a few to chose from... I know 3M makes one and there is also seafoam among others... there should be complete instructions on how to use them, most of them you start the car and unplug a vacuum line, generally the brake booster line, and hold the bottle at an angle where the vacuum of the engine can suck the liquid in slowly enough so as not to hydrolock the engine, it is extremely important to not pour the liquid in too fast, slower the better... I know with the seafoam when you get to where there is about a 1/4 of the bottle left you pour it in quicker so the engine will stall out just as finish pouring it in, you then let the car sit (off) for about half an hour or so and then start the car and go back and forth with the throttle for a couple of minutes and then take it for a drive... don't hold me to the exact details because I'm reciting from memory, make sure to follow the directions precisely because you can cause damage to the engine if done impoperly, if you don't trust yourself to do it you may want to consider bringing it to a shop to have it done.