GDI: Gasoline Direct Injection Engines

Gasoline Direct Injection = More Power, Better Efficiency!  

While it’s true that direct injection engines (GDI) develop more power and produce lower emissions, it is also true that there are some maintenance challenges that have plagued the design for many years.  

The evolution from carburetor to fuel injection (which was invented in the 1920’s) took until the 1980’s when virtually all new gasoline powered cars and light trucks were fuel injected.  The move to fuel injection increased fuel efficiency, lowered emissions, and enhanced reliability. Instead of the engine pulling the in the fuel, the system would deliver a precise amount of gasoline at the moment of the intake stroke.  

Fuel injection systems can be prone to clogged injectors which led to better gasoline additives and maintenance services designed to “clean” the injectors and fuel intake system.  We recommend an Air Induction service as routine maintenance @ 30,000 miles or two years, or potentially earlier if needed to restore performance for many vehicles.  

The dominant fuel injection system is called “port fuel injection” because the fuel is injected above the valves.  This has the effect of keeping the valves clean and free of carbon buildup. Absent that cleaning action, Carbon, a natural combustion byproduct, can accumulate to the point of causing performance issues and even significant damage.  Keep reading for a recent, real-life example from our repair facility.

In the past few years, “gasoline direct injection” engines have become more commonplace as manufacturers work to meet Corporate Average Fuel Economy (CAFE) standards mandated by the federal government.  

GDI engines put a precise amount of gasoline at high pressure directly into the cylinder just ahead of the ignition spark.  This type of fuel injection is more efficient and produces fewer emissions but, because nothing produces 100% combustion, some byproducts will be present allowing carbon to accumulate.  

Detergent additives and traditional fuel injection maintenance services have diminished effectiveness in these engines because very little of those chemicals make it to the surfaces where carbon is building up. 

One problem of carbon can build is that it can prevent valves from seating properly creating an effect much like that of a cutting torch.  The photo attached to this blog post shows this kind of damage. The “chunk” missing from the valve shown wasn’t broken off; it was burned off.  Obviously the vehicle presented a host of symptoms with one cylinder unable to hold compression.  

How does one prevent or manage carbon buildup in GDI engines?  Preventive maintenance, including a new service developed specifically for gasoline direct injection engines.  

Timely oil changes are important because, in addition to providing lubrication, engine oils have additives that are meant to “clean” and hold contaminants in suspension so they can be trapped by the filter.  These additives have a limited lifespan, as does the capacity of the filter.  

A GDI Fuel/Air Induction Service at Haglin Automotive uses proprietary chemicals and equipment available only to qualified repair shops.  The process relies on a skilled technician implementing an exacting process. While not inexpensive, the benefits are significant: improved performance, lower emissions, and carbon reduction in the combustion chamber to name a few.  

One major manufacturer has developed a special machine that is much like a sand blaster that uses crushed walnut shells under pressure to blast or scrub away carbon accumulations.  If that sounds like an expensive repair - it is.  

Again, we prefer effective preventive maintenance to major repairs.  

The recommended interval for the GDI service varies, but is advisable at any mileage when the engine seems sluggish or has other issues that aren’t due to other components.  Some customers have reported these kinds of symptoms in as few as 30,000 miles.  

As with so many things automotive, an ounce of prevention is worth a pound of cure.  Repair costs can be as high as twenty times the cost of the service, making it a prudent choice for vehicle owners who want to maximize reliability, efficiency, and comfort.

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