Volatility, or a fuel’s tendency to vaporise, is the key characteristic for a smooth ride, or car’s drivability. Drivability describes how easily your car starts, warms up, drives and accelerates. When the spray pattern of fuel from the fuel injector is restricted in any way, the vaporisation can be negatively affected. That has serious implications on your car’s drivability because only fuel vapor actually burns. It doesn’t burn at all in liquid form.
Port fuel injector (PFI) deposits form during the hot soak period after the engine has been turned off. The stationary gasoline trapped in the injector tip is exposed to a higher temperature for a longer time than the fuel that flowed through the injector when the engine was running. The heat degrades the fuel, initiating deposit formation. In the absence of an effective additive, injector deposits can form quite rapidly if the base fuel is relatively unstable and if a car is used predominantly for short trips. Cold-start and warm-up drivability can be adversely affected. This occurs because the deposits act somewhat like a sponge, absorbing and then releasing fuel, which upsets the ratio of fuel and air, particularly as the engine is changing speed.
Other valve deposit problems include valve sticking caused by deposits interfering with the valve stem sliding in its guide. Another problem would involve burned valves wherein severe deposits prevent the valve from seating properly.
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