Black smoke comes out tailpipe on 4cyl s10,no power

What color is the smoke? White? white with a blueish tint, or black?

assuning there is nothing major wrong, get some forte injector and use it as recommended. I once had a renault laguna diesel fail an MOT test, a roadworthiness test that is, on emissions...it was absolutely chucking out black smoke but the engine ran well. I put 2 bottles of injector cleaner in the half full tank and went out for an eighty mile drive revving the engine in the lower gears. I returned to the testing station an hour and a half later and the engine was running perfectly.
Alternatively, assuming the engine runs well but is just a little smokey, have it terracleaned, this will remove most of the carbon deposits from the engine/exhaust and should increase the life of your engine simultaneously improving fuel economy

White or blue smoke? If white does your hand get damp holding up to the tailpipe when the engine is running? Does the radiator boil over/engine over-heat easily? Flat head engines are notorious for running hot especially if not moving. Flat-heads don't cool well as a general rule and the older radiators are not very efficient heat exchangers. If the smoke is white then the headgasket is blown or the head or block is cracked (the first two are more common). If the smoke is blue then the valve guides and/or the piston rings are worn fairly severely. Ironically the easiest way to damage the piston rings or valve guides in a flat-head is to run it hot.

Bad carb or fuel injection issues- the system is fuel rich (black smoke) and also fuel rich system can make the idle low. Many things can cause this but thses are just a few.

What year, make and model car is this? Most likely, black smoke is
usually a carburator problem. If it's fuel injected, black smoke can be caused by 1) leaking or faulty fuel injecters, 2) faulty choke, 3)dirty air
filter or 4) faulty distributor cap and/or rotor. Hope this helps.

Hi there:
Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

How did the fuel get into the cylinder in the first place? Some of the causes of excess fuel are a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or computer sensor. If black smoke is present, check the engine oil as in the white smoke example to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil. Call your mechanic and advise him of what you have found.

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The white smoke is probably steam caused by coolant getting into the cylinder(s) either from a faulty head gasket, cracked cylinder head or cracked engine block. The loss of heat from the heater indicated that coolant was being lost..

A puff of smoke when you start up indicates worn valve seals.That's why all your work didn't fix the problem and it doesn't show a code. It's a pain in the --- job that requires some specialized tools so I guess it depends on how bad it bugs you,if oyu want to fix it.

blown head gasket. black smoke means that oil is getting into the cylinder.