Fuel additives designed to clean fuel injectors, carburetors, ports and intake valves do work, according to RepairPal, particularly if they have polybutene amine, or PBA, as part of their chemical makeup. However, those with polyether amine, or PEA, chemistry deliver the same benefits without causing deposits in the combustion chamber.
The U.S. Environmental Protection Agency requires that all gasoline sold in the United States has a minimum amount of additive to keep sediment from aggregating in the fuel system and engine. However, meeting the minimum standards doesn't keep all deposits from building up over time. People who use PBA-based fuel-injection cleaners are moving the buildup down the system to the combustion chambers. Over time, this makes the engine knock and increases the unhealthy level of emissions from the engine.
Fuel injector cleaners with PEA also keep the combustion chambers clean, keeping the engine from pinging or knocking and making cold start-ups less troublesome. These additives also clean away sulfur deposits that build up near the gas-gauge sensors, often causing malfunction. As of 2015, many brands of fuel-system cleaners rely on PEA chemistry, including STP, Valvoline and Gumout, and many service departments in car dealerships use PEA chemistry as part of their fuel-injection cleaning services.