When compared to a vintage carburetor, modern, computer-controlled fuel injections seem almost maintenance-free. However, modern fuel-injected engine packages have fuel-related components, such as the fuel pump, filters, and injectors, that need maintenance from time to time.
How do you know when fuel injectors need service?Because port fuel injectors are located in a very hot area in the engine, they are subject to deposit buildup problems created by the high temperatures the fuel is exposed to. When deposits foul the injectors, fuel flow is restricted, and the spray pattern is distorted. As a result, there will be a gradual loss of engine performance, a stumble/hesitation on acceleration, or both. Dirty injectors can also hinder fuel economy. And while these problems normally appear over time with miles of driving, one bad tank of gasoline can quickly dirty the fuel injectors.
When the fuel injectors' condition is questionable, shops commonly use a computer scan tool to check them. The data from a scan tool reads the amount of fuel trim correction the engine's computer is making to the fuel injector on time so the engine has the correct air/fuel mixture for your driving conditions.
Keeping Injectors Flowing ProperlyIn theory, all the injectors should flow the same volume of fuel to each cylinder, but that is not always the case. Fuel injector production lines allow a +/- 2 percent flow variance, but sometimes one outside the normal flow tolerances will get through. And as we've said, fuel flow will change as the fuel injectors are dirtied or restricted from use and fuel-related contamination. Obviously, an engine performs best when each cylinder has the correct air/fuel mixture, but when the injectors' flow varies, the air/fuel mixture delivered to each cylinder of the engine will vary as well. And when that variation gets in the range of 6 to 8 percent, the engine's power and drivability suffers.
The best preventive medicine to keep fuel injectors clean is gasoline with additives that prevent deposit formation. That's why many car manufacturers recommend gasoline that conforms to the new "Top Tier" standards, which has detergents that help keep fuel injectors clean. Many major brands are now being blended to the Top Tier standards. Using an in-tank fuel injector cleaner such as Chevron's Techron or Techron Plus when you change your engine oil is also good preventive maintenance.
Another preventative measure when parking your street rod for the winter, or any time the fuel will remain in the tank for more than two months, is gasoline storage stabilizer such as Gold Eagle's Stabil. As gasoline ages it turns into a gummy, varnish-like substance that may cause the fuel injectors to stick open or closed, restricting fuel flow or plugging it completely. And the only way to clean fuel injectors that have been exposed to bad gas is to remove them and service them with an ultrasonic fuel injector cleaning system-or replace them completely.