If you only drive long distances and do no stop-and-go driving there is very little need to use fuel system additives to keep carbon buildup from forming on the intake valves, as long as your using a Top Tier gasoline. This will give you the minimum additives required by the auto manufacturers. Is this so?Yes, however for most drivers, additional additives are needed to keep carbon buildup from forming on the intake valves. Lack of gasoline detergent additives in modern gasoline coupled with high concentrations of alcohol causes carbon buildup on the intake valves. The carbon builds up on the back face of the valves, causing different symptoms.
The carbon acts as a sponge and absorbs the incoming air/fuel mixture causing a lean condition which results in hesitation when accelerating. In extreme cases can cause a lean “pop-back” condition which manifests as a misfire/backfire into the intake manifold. Carbon which sticks to the intake valve stem or on the valve guide will make the valve stick open. When the engine is turned off and engine cools down, the carbon turns hard and causes a valve to become stuck in the open position. The next time the engine is started it will have a dead cylinder because of the valve remaining open. This results in a no-start condition or dead cylinder. Proper chemical decarbonizing treatment can remove this carbon from the engine.
