What You Haven’t Been Told About GDI


Gasoline Direct Injection (GDI) engines are not new technology. The first automotive direct injection system was created by Bosch and then developed in 1952, It was placed in the 1955 Mercedes-Benz 300SL. From the early 2000’s until now, more automotive manufactures have moved to GDI engines in their vehicles and some vehicle manufactures are using exclusively GDI engines in their vehicle line-ups.


Some of the benefits of a GDI motor are improved fuel economy and high power yield. Emissions levels can likewise be more precisely controlled within the GDI framework. Benefits of GDI engines include exact control over the measure of fuel and injection timing that can be varied depending upon engine load. Also, some engines operate on full air intake. This means no air throttle plate wiping out air throttling losses in some GDI engine. Compare this with a conventional fuel-injected or carbureted engine and GDI engines greatly improve efficiency and reduces piston ‘pumping losses’.

port injection GDI

In a GDI engine, fuel is sprayed precisely within the combustion chamber, (instead of the air intake). This allows for a more complete and even burn. Ideally, this more complete combustion means better fuel economy and higher power. GDI engines can burn leaner than port fuel injection engines and a leaner mixture allows fuel to be burned much more conservatively.


GDI requires fundamentally higher fuel pressures than traditional port injection. This puts a lot of strain on every component in the fuel delivery system, and the fuel itself. The additional stress is not problematic when the system is new, but in as little 5,000 varied miles deposits can form inside the system robbing you of power and fuel economy.

Higher operating temperatures of GDI engines can lead to engine oil evaporation. Oil vapors circulating in the cooler regions of the engine create deposits and pooling. Some of those areas include intake boots, valves, piston crown, head squish area and catalytic system.


Higher pressures and operating temperature aren’t the brunt of the problem with GDI engines. The largest concern is due to the latest unburned hydrocarbon (UHC) regulations. Unburned fuel and oil vapors from combustion are vented from the exhaust stroke of combustion into the intake side, (Variable Valve Timing, VVT) in order to help cool combustion and prevent the oil vapors from exiting through the exhaust. In a port injection engine system, these vapors are ‘cleaned off’ the intake valve with a mostly constant stream of gasoline from the injectors. In a GDI engine however, the injector has been moved into the combustion chamber, thus the fuel does not come into contact with the intake valve. These vapors now have a tendency to bake onto the valve and greatly reduce performance. Since GDI ignition has a tendency to produce far more soot than port injection, the problem is compounded.

GDI Piston top and cross hatch scoring

The soot accumulation is a result of more than just the fuel system. New low tension piston rings are being incorporated into the systems to help reduce friction and further increase fuel efficiency. The oil retention rings are thinner and exert less pressure against cylinder walls than conventional rings.  This can and does allow for the accumulated deposits to more easily find their way into and “stick” the rings.  As it’s always been, a “stuck” ring can lead to wear on the cylinder walls cross hatch, this leads to an irreversible condition and again – engine tear down and hard part replacement.

What is even more disturbing is these deposits can break loose causing damage other downstream components. (catalytic converters, turbochargers, etc.). Most vehicle manufacturers have done their best to integrate components and systems to capture these oil vapors and particulates, but no system is effective 100% of the time. Many consumers have been saddled with large repair costs as a result and even diesel engines have not been immune to these types of issues.

The reason these issues have snuck past manufactures is because they won’t show up in a 500,000 mile “torture” test.Many U.S. drivers don’t drive their vehicles as expected by the manufactures.  We tend to drive on many short trips, i.e. the store, the quick errand,  or just over to a friend’s house.  The issues tend to show up after a few of these short trips which simply don’t allow the engine to reach optimal operating temperature. As we approach the efficiency limits of the internal combustion engine, the engines themselves (and their support systems) have become more advanced in complexity, thus fewer deposits are having a larger impact on performance. 


For decades BG has offered simple and efficient solutions for today’s, complex automotive technologies.  Most often, a product that can be poured into the oil or fuel system, or a piece of equipment can keep the engine clean and deposit-free. GDI engines, however, present new challenges.

In port fuel injection engines, the injector sprays fuel on the back side of the valve so adding a fuel system cleaner to the fuel will help clean deposits from the intake valves. In GDI engines, however, because fuel is sprayed directly into the combustion chamber—and not onto the back side of the valve—traditional fuel treatments are not as effective in cleaning the intake and exhaust valves.This means the only way to get the valve bloom and stem clean would be through a lengthy teardown process.  Since engine teardown isn’t a preferable option, BG has and continues to work on a solution. 



BG’s simple 3 part GDI Performance Service follows our simple Keep It Clean preventive maintenance line of thought.  It consists of a more thorough oil change to prevent the formation of, and allow clean up of the deposits found throughout the engine.

BG EPR Engine Performance Restoration, when added to the oil system breaks down and softens those hard-to-remove deposits from piston rings, allowing them to be removed with the used worn out oil, helping to restore compression and preventing wear on the cylinder wall.  When combustion chambers are properly sealed, compression is improved  reducing oil dilution through blow-by, (which is common in GDI engines). BG EPR will help restore lost fuel economy and power. 

BG MOA  engine oil supplement inhibits engine oil thickening under even the most extreme driving conditions. It fortifies all qualities of engine oil to help withstand fuel contamination and maintain important lubrication qualities for a longer period of time; even under extreme temperatures. It keeps ring lands, hydraulic cams and lifters and other engine components clean.

BG 44K fuel system cleaner rapidly and successfully cleans the entire fuel system. BG 44K provides rapid cleanup of carbon-covered piston tops, fuel injectors and other crucial combustion areas. Because it provides efficient removal of upper engine deposits, it decreases issues caused by deposit buildup such as engine surge, stalling, stumble, hesitation and power loss. BG 44K quickly restores engine performance and improves drivability.

Together these three products have repeatedly demonstrated the ability to keep GDI engines clean and prevent potential complications. As vehicle manufacturers continue to shift towards complex technologies like GDI, low tension piston rings, multi cylinder displacement, and VVT for better fuel economy and lower emissions, we at BG will continue to work on solutions to help maintain these engines. Helping them to last longer, and perform even better, so that drivers can enjoy the benefits and performance they offer, and not suffer from the complications they can often succumb to.  Watch the video at the end of this page to see exactly how this service works.

Once the motor has been cleaned up, it’s essential to maintain the cleanliness and avoid more deposit buildup. The BEST way to clean these tough-to-remove deposits is to avoid them in the first place. The Keep It Clean approach utilizes three of BG’s most effective products (MOA, 44k, and EPR). The BEST way to do that is with the BG GDI Performance Service at each oil change interval.


GDI parts 1 and 2

BG has a two-sided approach to the potential complications found within  GDI engines driven by customers who haven’t changed their maintenance intervals and/or believed the 10,000 mile oil change interval was appropriate: These customers may require our Clean it Up and then Keep It Clean! strategy.

The ‘Clean it Up’ is for GDI engines that have accumulated several thousands miles and have the resulting deposit buildup to confirm it. While the clean it up approach is an in-depth process, compared to a complete engine teardown, it’s the much preferred option!

BG Gasoline Direct Injection Cleaner, PNs 271 and 272, consists of a two-part process to quickly soften and disperse baked-on deposits, which build up on the intake valves of direct-injected engines. With the GDI Service Tools, PN 9060, the technician can remove harmful deposits without the complete disassembly that’s typically required.

Once the motor has been cleaned up, it’s essential to maintain the cleanliness and avoid more deposit buildup. The BEST way to clean these tough-to-remove deposits is to avoid them in the first place. The Keep It Clean approach utilizes three of BG’s most effective products (MOA, 44k, and EPR). The BEST way to do that is with the BG GDI Performance Service at each oil change interval.



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