An Italian tuneup usually refers to a process whereby a motor vehicle engine is run at full load for extended periods in order to burn carbon buildup from the combustion chambers, spark plugs, and exhaust system. It is performed after a traditional tuneup and often accompanied by an addition of fuel system cleaner to the fuel tank. This can also be performed before each oil change interval with the addition of a good quality fuel system cleaner, then a few redline runs under load, after the engine has reached operating temperatures. Most carbon will escape through the exhaust but traces will find their way to the oil pan, hence doing so just prior to an oil change. It is particularly useful for vehicles that are only operated at low speeds on short journeys, but can help any vehicle to run cleaner longer, and for diesel vehicles prior to emissions testing. Driving for 20 km (12 miles) is typical.
The origin of the Italian tuneup comes from Ferrari. Owners would drive their cars infrequently and never run them hard, which causes the engine to build up enough carbon inside to affect performance. Mechanics would perform a "tuneup" by driving several laps around a race track to get the engine hot enough to burn out the built up carbon. Cars before the advent of modern engine lubricants and fuels, often had a 'de-coke' by hand, after removing the cylinder head, as a scheduled service operation.
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