Home / Auto News / News article: Should You Buy a Car With Direct Injection? - AutoGuide.com News
 |  Dec 07 2012, 9:01 AM

Despite advancements in hybrid power-trains and electrification technology, gasoline engines remain the predominant choice in passenger cars because of continued efficiency improvements, most recently through the increased use of direct injection technology. But are you gambling when buying a car with DI, which still has its fair share of concerns and problems? 

Direct-injection is becoming commonplace in new cars thanks to its positive effect on fuel efficiency. “The requirements for higher fuel efficiency being stipulated by the EPA assure direct injection will be an increasingly common technology on cars going forward,” Says Karl Brauer of TotalCarScore.com “A such, automakers will have to figure out how to make it durable and cost effective.”

It’s the next generation of fuel injection, which replaced the carburetor somewhere back in the ‘80s. By result of squirting fuel right into the individual cylinder, the engine gets a higher quality of combustion and an increase in combustion efficiency. This means that a smaller engine with direct-injection can make as much power as a bigger engine without direct injection. By precisely timing and placing the injection of the fuel into the cylinder, engineers have managed to ensure a more efficient combustion. Therefore, it pollutes less too.

NEW TECH, NEW PROBLEMS?

However, direct injection isn’t without its critics. “There is a process of getting the technology to not only work but to be durable and cost effective,” Says Brauer. “The latter always takes time when a new technology first enters mainstream production.”

There are many longevity concerns with direct injection equipped engines. For example, the high pressure injection used in these engines causes a lot of stress on the fuel pumps. Regular fuel pumps in non-direct injected applications operate at much lower pressure than the high-pressure fuel pumps in direct-injected power-plants. The difference is in thousands of PSI.

Some high-pressure fuel pumps, like those used with BMW’s twin-turbo direct injection engine in the 2007-2010 335i, the 2008–2010 135i, 535i and X6 xDrive35i, as well as the 2009–2010 Z4 Roadster sDrive35i have been known to fail prematurely.

Another problem with direct injection is with ethanol fuel. Ethanol is known to speed up the corrosion rate of some metals that are used in an engine. With the higher pressure of a direct injection engine, and thanks to the fuel injector being exposed to in-cylinder explosions, there’s a higher chance of a problem or failure. Because of this, it’s more important to use higher quality fuels.

Finally, the biggest concern with direct-injection technology is with carbon buildup. In a direct injection engine, oil droplets tend to get ‘baked’ on the valve. Carbon buildup can create a lot of headaches in the long-term, with build-up being bad enough to make extra noise during operation and damage the engine. At the very least it can reduce fuel mileage, and affect performance.

This issue can affect other components in your car’s engine, like turbochargers or catalytic converters. Luckily, some automakers have filtering systems in place to catch droplets and debris.

Newer implementations of direct-injection are designed around these problems. Toyota’s D-4S system that is in use in some of its cars such as the Scion FR-S and Lexus GS350 have a second set of port injectors (not direct injectors) that run when needed to help clear off the carbon build up and optimize performance. Wade Hoyt from Toyota’s communications team explains “The main benefit is that it allows the compression ratio to be raised without pre-ignition or ‘pinging.’ Higher compression produces more horsepower.” Wade points out that “All of the D-4S equipped engines have higher-than-usual compression ratios.”

OLD SUPERCAR TECHNOLOGY, NOW IN AFFORDABLE CARS

While becoming commonplace, direct injection technology is not new. The first vehicle with direct injection is said to be the race-car turned production car, the 1955 Mercedes-Benz 300SL. The usage of direct-injection is considered to be one of the key factors in helping the car reach its record breaking top speed of 161 mph. Where the 300SL featured supercar-like engineering like direct injection, the technology is now it’s being used in cars as affordable and frugal as the Hyundai Accent.

Direct injection is helping to extend the dominance of gasoline powered vehicles everywhere. It provides more power, helps with fuel savings and can lower emissions without any change to the way the car drives.

With direct injection used in the tiny 1.6-liter engine found in the Hyundai Accent, the car can make a (relatively) whopping 138 horsepower. The engine in the Honda Civic, which doesn’t have direct injection, needs to up the displacement to 1.8L just to make similar power. The 2.0L Skyactiv-G engine in the Mazda3, which makes 155-hp thanks to direct injection, is seven horsepower more than a non-direct injected 2.0L Subaru boxer engine found in the new Subaru Impreza.

By itself, direct injection is pretty good at helping new cars get more range with each tank of gas, but when compared with other engine technologies, it becomes even more impressive. By combining direct injection with turbocharging in the Cadillac ATS 2.0T, the engine can make more than 270-hp, even though it displaces just 2 liters. The new BMW 328i also combines turbocharging and direct-injection to make heaps of power in a small package. The two technologies come together in harmony help make a surprisingly effective package of power and fuel economy.

It’s clear that the adoption of direct injection by automakers hasn’t peaked yet, and durability concerns are known. Additionally, with recent news from Hyundai and Kia that fuel-mileage claims are being downgraded, there’s a chance that some direct injection implementations aren’t as successful as marketed.

With some more time and development, gains in reliability are certain to be achieved. And by combining direct injection with variable valve timing, smart alternators and start-stop features, the extra mileage achieved is certain to make the efficient and effective gasoline engine the dominant powertrain choice for years to come.

 

  • http://twitter.com/CanyonDriver Mike Garcia

    Maybe a person shouldn’t buy direct injected turbo vehicles, since I’ve yet to see an N/A go through serious recall.

  • James K

    Question: Should you buy a car with Direct Injection?
    Answer: Not if its from Korea.

  • Ron

    The Hyundai Genesis Coupe 2.0T does not have a GDI engine in it. Only the 2013 3.8 V6 which is NA has GDI.

  • http://twitter.com/Sami_HA Sami Haj-Assaad

    Corrected, thanks for the heads up Ron!

  • ademello

    The big question that remains has to do with the long-term effects of GDI on vehicle reliability and service cost, meaning long after warranties have expired and manufacturers can no longer be held liable for anything.  What will GDI mean to people that hold on to vehicles beyond 10 years? Is this a time bomb that will leave people stuck with expensive repair options and vehicles they cannot sell? 

    It is funny how everyone kept on pounding Honda for being so behind technologically by not joining the GDI bandwagon.  Honda is generally more conservative about deploying leading edge technologies, and there is some smart reasoning behind that ideology.

  • http://profile.yahoo.com/2I5ONTMZEO7JOOVX4MYPGVNABQ Kica

    A la Lexus IS250.  Oh the poor souls, with no extended warranty, who have to replace the pistons b/c of GDI. 

  • DRJJ

    Careful what you ask for, you might get it! Toyota Camry-conventional transmission and fuel injection!

  • http://www.facebook.com/john.marc.526 John Marc

    Sorry to disappoint but the 2013 Honda Accord 185-hp, 2.4-Liter, 16-Valve, Earth Dreams DOHC i-VTEC® 4-Cylinder Engine has DI :(

  • Sunny

    The savings in fuel consumption may not be able to offset the additional cost of maintenance of the engine due to carbon build-up.

  • DRJJ

    Tell em about the ultra high fuel pressure, related components, costs and risk with DI!

  • John Scott

    I imagine too the extreme exposure to heat will cause carbon build up and earlier failures. Also the injectors will certainly be of higher costs. Add to that a older high mileage direct injected engine will also deal with oil consumption clogging of those injectors. When you have the injector in the intake system you avoid those exposures. I personally would wait to see if the brains in engineering have solved any problems? Or just created new ones for owners.

  • John Scott

    Most auto makers only worry about longevity of components for their warranty period.
    So its safe to say direct injection will most likely serve the car maker well enough for that. Its the longer lifespan of the car for maybe a second or third owner I think will have to deal with direct injections negatives.

  • hoverlover

    I have a 2008 Mini Cooper S with direct injection. The intake valves coked up after 35,000 miles. The repair was covered under warrantee. The service rep said, “We’ll clean off the carbon and re-program the engine so this will never happen again.”
    Today I got my Mini back from the shop after having the carbon removed – again (70,000 miles). The service rep said, “We cleaned off the carbon and re-programmed the engine so this will never happen again.” This one cost me $800. I WILL be talking to Mini corporate about this issue.
    Direct fuel injection sucks.

  • Lew

    The author needs to get his information correct. The Honda Civic does have direct injection as of 2013. My Civic sedan gets between 32 to 34 city mpg and 40 to 42 highway cruising.

  • Auto Motive

    Vehicle maintenance is important which includes using a valve injector cleaning agent between oil changes. I find sea foam to be the best product for this application. I add this to my gas every 10000 miles. I just turned 20k on my Optima Turbo and so far its running like new. Direct injection or fuel injection I use this additive along with synthetic oil in all five of my vehicles. It has worked for me over years and would highly recommend it to all.

  • Pringles

    By it’s very definition, Direct Injection sprays fuel directly into the combustion chamber, not into the inlet port throats. Sorry to say, but Seafoam added to the fuel will do precisely squat in cleaning the inlet ports of oil vapour on a Direct Injection engine.

  • Mifuel

    The Integra 1.8L engine produces 200hp an engine develop in the 1990′s
    Compare that to Mazda 2.0L Skyactive that only produces 155hp