Black smoke from the exhaust indicates that too much gas is being burned (the air/fuel mixture is too reach). So then of course, what we need to do is determine why so much gas is being burned. Well, one thing that will cause this is a clogged air filter, let's check it out.
The reason why black smoke coming out from the exhaust
(1) Clogged air filter.
(2)Problem with fuel injector system.
Car troubleshooting
Locate the air filter. Refer to a manual that covers your car if you need help finding it. Remove the filter and closely examine it.If there a lot of dirt in the filter. Then the clogged air filter is likely to cause the problem The black smoke coming from the exhaust is excess gas being burned in the engine's combustion chambers. A clogged air filter will restrict the amount of air that reaches the engine and thus cause the air/fuel mixture to be too rich (i.e. too much fuel). As indicated above, this is only a likely cause of this problem. It is possible something more serious is at fault.
What to do?
Replace the air filter. Any auto parts store will carry a good selection of filters. If this doesn't solve the problem, please rerun this consultation for further analysis.
However, if there is not a lot of dirt in the filter. Rule out the filter. Another possibility has to do with the car fuel injection system In particular, one of the system's sensors may have gone bad. This takes us to the following.
The fuel injector sensor could be bad. This car's fuel injection system involves many electronic sensors. These sensors measure various engine factors. The resulting data is used to calculate how much fuel should be injected into each cylinder. If one of these sensors goes bad, the air/fuel mixture will be wrong. As with the car, black smoke will result if the air/fuel mixture is wrong in the sense that it's too rich (i.e. too much fuel). Failed sensors that typically cause black exhaust smoke are the throttle position sensor, engine coolant temperature sensor, and the mass airflow sensor.
What to do?
You will need to verify that one of the sensors is indeed bad. The only way to do this is to have a mechanic hook the car up to an engine analyzer. The cost of such an analysis is not too much. The analyzer will typically display one or more trouble codes (i.e. numbers) which the mechanic will use to determine if a sensor has failed. If a sensor has indeed failed, have it replaced.