Direct injection systems require additional maintenance

By Doug McAllister

Many newer cars on the road today have what's called GDI fuel injection. Most manufacturers have moved away from port fuel injection to direct injection as a way to get more performance and fuel efficiency from smaller power plants.

It is amazing the amount of power that comes from a small four-cylinder engine these days. In fact, a GDI four-cylinder engine performs better than some V-8s of days gone by.

The benefits of GDI (gasoline direct injection) don't come without some negative characteristics, though. These negatives come in the area of added maintenance - and here is why.

Because gasoline is injected directly into the combustion chamber, the valves in your car's engine never come into contact with liquid fuel, so they never get cleaned by the gas.

The valves are subject to nasty carbon and other byproducts of combustion buildup that can happen fairly quickly, especially when using a lower grade of fuel, or one with excessive ethanol. Over time, this buildup can cause engine misfires, "check engine" warning lights and other drivability problems.

Until recently, the only fix was to disassemble and mechanically clean the affected areas with a soda or walnut blaster. However, a cleaning system recently has come on the market that can be injected into the intake plenum. This cleaning will break down the carbon and restore the engine to normal operating condition.

It is recommended that this service be done every 15,000 miles to keep the car in optimal running condition.

• Douglas Automotive is at 417 W. Main St., Barrington; 123 Virginia Road, Crystal Lake; and 416 Northwest Hwy., Fox River Grove. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.