I have a 1996 chevy caprice black smoke

Black smoke means burning oil!! Get ready to do a full rebuild!! Sorry!!

It only do it every now nd then @Olsonboy

Ok cuz I was wrong lol white smoke is oil... Black smoke is a fuel problem.. Maybe trash in the fuel, try a fuel filter

Blue smoke is oil, white smoke is coolant burning, black smoke is too rich of a fuel mixture

Green smoke is organic stuff and not legal in almost all states. Black smoke is fuel, so check the filters, both air and gas. Get a computer read on it as bad sensors could cause the cats to fail and they are expensive. The computer will put in more fuel if the air sensors are off and adjust the air/fuel mixture to compensate.

What do u mean by air sensors @califcarson

The air flows into the engine and is then matched by computer to insure the proper air/fuel mixture is in each cylinder via the EFI system. If the sensor gets a poor reading, it will adjust the mixture. If the air sensor is the issue, the air/fuel mixture will not be correct. Too little or too much fuel is added to the mix.

Ok my car hesitate when i pick up speedwhat could tht be ? @califcarson

Too much gas and it is not igniting properly? You need to have the air flow mixture checked and adjusted. If it was a carburetor car I'd say the float is bad it is dumping too much fuel into the intake manifold.

So how do i check it

Unless you have the electronic computer reading equipment you have to take it to a garage that has and have them do a diagnostic on the readouts.

What happens when sugar was put into the motor. Not in the gas tank.