Automobiles and locomotives are powered mostly by Internal combustion engines. The input of Fuel, Air and Spark in definite proportion at a defined time into the combustion chamber causes an output of mechanical and heat energy, the reaction that takes place give rise to emission of residual gases(exhaust gas) at the tailpipe. If a complete combustion is achieved these gases are not expected to have any smell or color but if otherwise we will notice Black smoke, Blue/grey smoke or a Foggy white smoke. It is possible to use results from the examination and analysis of the smoke to tell the type of emission issues the engine has. Note that this is not 100% proof as further diagnosis will help to verify if the initial analysis is correct or not.
The question that comes to mind is, How do I know why my engine is emitting a particular type of smoke or exhaust gases? Note all residual gases mean there is an issues with your engine, but it is always very Important to check.
Black smoke could be caused by clogged air filter, ignition timing off, blocked air intake manifold or clogged injectors due to incomplete combustion and has a relative effect on other emission related components. its very distinct when produced by petrol or gasoline powered engines. The smell and spitting of raw fuel can be noticed from the tailpipe as well as black soots of carbon monoxide that forms a thin layer on the tailpipe orifice. The engine will consume more fuel and lack equivalent power. Any vehicle with this smoke type shows that its running Rich, meaning more fuel, less air. Vehicles with these symptoms runs rough and lack power either at low RPM or higher RPM depending on the Air/Fuel strategy utilized by the vehicle manufacturer.
Faulty Mass Air Flow Meter (MAF) or Volume Air Flow Meter and wiring to ECU
Faulty Oxygen Sensors or Air/Fuel Ratio Sensor and wiring to ECU
Obstruction to Air intake
Stuck open injector
Dead, Rich Misfire in the Engine
Rough vehicle operation as vehicle misfires.
MIL or ‘CHECK ENGINE’ comes ON
Damaged Catalytic Converter
Excessive Fuel consumption with little or no equivalent power
Backfire and detonation could occur.
Blue grey Smoke is maily caused by worn pistons, valves or cylinder and oil leaking into the combustion chamber. Its not as noticeable as the former, but it is worse than the former. A distinct blue smoke will always be produced by an engine that has a lower engine fault, this fault affects only the lower engine assembly. When fuel is mixed with engine oil and burnt, the resulting smoke will be a blue smoke that will leave no carbon soot but will be much in volume. The color could get lighter from light blue to a thick white smoke with smell of burnt oil. Considering the construction of the engine, Oil is meant to cool the heat built up in each cylinder during combustion, and the scrapper rings are responsible for taking or scrapping off the engine oil as they prevent such from leaking into the combustion chamber; when this rings are worn out, smoke begins to develope and gets worse without repairs.
Bad or worn Piston Rings
Faulty Engine Gaskets
Excessive choky smoke
Environmental nuisance and pollution
Noisy Engine operation and poor engine performance
Foggy White Smoke is always experienced in the morning as the engine tries to achieve threshold, though there are times when it could be as a result of a leaking head gasket, crack engine block or cylinder head. Complete fuel combustion should emit CO2 and Water (gaseus steam) as one of its major final product. Seeing this in a vehicle gives a performance satisfaction and some times this comes as trinket or droplet of water from the exhaust pipe but its not meant to be for a long time. if it is noticed to stay longer there may be need to further investigate the engine. The vehicle will run smoothly and can be operated even in a workshop for hours without hurting anybody.
Diagnostician, use Long Term Fuel Trim (LTFT) and Short Term Fuel Trim (STFT) valves as accessed on the scan tool to analyse if engine is running Rich or Lean. Examination of the MAF response when graphed during a Wide Open Throttle (WOT) will show if the MAF sensor is the cause of the black smoke or not. A Leakdown Test will be useful in verifying if the Rings are Bad, Stuck open Valves (Intake or Exhaust) e.t.c. Finally an Exhaust Gas Analyzer connected to the tail pipe will measure approximately the quantity of the constituent gases in the residual gae, hence a basis to judge Lean or Rich Conditions.
Engine performance has a direct relationship with the type of residual gases that are emitted from the engine tailpipe after combustion. The ability to effectively analysis these residual gases make it very easy to solve performance related issues.
If you see white smoke coming out of the car exhaust pipe in thin wisps, but it’s only when you start the engine, then there’s no need to worry. This is due to an accumulation of condensation that finds its way out through the exhaust pipe.
If the car has a diesel engine, lots of white smoke coming out of the exhaust when you start it up indicates that the fuel pump injection timing is off. You must bring your car to a mechanic to check this issue and, if necessary, fix the fault. You can also check your fuel pump injection timing yourself to know if this is the cause.
If white smoke continues to come out of your exhaust while the car is running, and not just when you start it, it may be leaking coolant which is then being burned. This problem is not very serious but you must go to a professional mechanic as soon as possible to fix the leak.
Your coolant may also have run out in which case you will need to stop the car immediately as it will be overheating. Check the levels of coolant to make sure this is the problem and follow these steps to know what to do if your car overheats.
The fact that the car is emitting a lot of white smoke from the exhaust when it’s already running can be a sign of more serious and costly problems, and it should be repaired as soon as possible. The smoke could indicate more serious problems with the fuel filter, cylinder head, the cylinder head gasket or even a crack in the engine block. Keep in mind that problems of this kind can be quite costly.
If you regularly keep up with the maintenance of your car, you can detect these problems early, before they become expensive or even impossible to repair.
Be a fixer not a part fitter….Stay dirty…