If the exhaust smoke is black:

Black exhaust doesn’t always indicate impending doom. If your car emits a little black smoke at start-up, but it clears up as the engine warms to operating temperature, don’t worry – that’s normal for some cars. If it continues after the car warms up, there’s cause for concern. If that’s the case, here are the likely culprits:

Clogged or dirty air filter: An essential part of a vehicle’s fuel system, an air filter stops airborne contaminants from getting sucked into car’s engine, where they can clog up the works. The remedy is simple: replace the filter.

If the problem persists, it’s an indication that your vehicle’s air-to-fuel ratio is askew – specifically, it is burning too rich or more fuel than air. Two of the most common reasons for this are a malfunctioning fuel pressure regulator or leaky or clogged fuel injectors.

Bad fuel pressure regulator: A vehicle’s fuel system is designed to work within a specific range of pressure, which is controlled by a fuel pressure regulator. If the regulator is on the fritz, the pressure will fluctuate outside of the system’s specified range. If it falls too low, there may not be enough fuel reaching the engine to start it. Too much pressure may result in over-fueling, which can make your engine run rough and deliver poor fuel mileage, among other things. The remedy is to replace the fuel pressure regulator.


Leaky or clogged fuel injectors: Fuel injectors are small electro-mechanical devices used to spray a predetermined amount of atomized gasoline (a mist of gasoline) into a vehicle’s intake manifold, which is directly in front of the intake valve. The gas is drawn into the combustion chamber and mixed with a predetermined amount of oxygen to optimize the efficiency of the burn or combustion event. The remedy is to repair the fuel injectors.