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Should You Buy a Car With Direct Injection?

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.

56 Comments

Mifuel says:

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

John Smith says:

That’s the difference between an engine that’s hand built and blueprinted and one that’s mass-produced. Another thing to note is the ITR engine had minimal torque and that hp was only produced at redline and the Mazda motor has torque near equal to it hp rating and at much lower RPMs. IOW, the ITR was flat-footed unless you drove it like you stole it – coming from the former owner of a slightly less powerful GS-R and last-gen Civic Si.

Wink Mcgee says:

I need to find a GSR before they’re all gone! Way better looking car to then todays. Also something I can actually work on! Owned honda/toyotas that have all been 20 years old or older. Logged hundreds of thousands of miles, with nothing but brakes, exhaust, tires, oil, filters you know regular maintence stuff. My first and last domestic vehicle was a ford, never looked back! Problem I see is japanese vehicles peeked in the early 90’s after that we started getting americanized versions of japanese models, and things went down hill. Now when I look at a tacoma in NA and a 70 series land cruiser sold in every other market but NA, I start to see the BS that toyota NA has become… Heck even the domestic brands offer 4wd diesel vehicles in other markets! I’m sure there’s a bunch of BS reasons why they aren’t offered here, but VW sells diesel passenger cars here so what’s the problem? Would a small over built toyota diesel truck sell here? I think so, toyota doesn’t…

dibble says:

I have been ruining a petrol direct injection Kia Ceed for about 2 years now. Fuel consumption is more or less the same as previous port injection cars. I’ve noticed that the exhaust is heavily sooted – unlike the previous exhausts – which were totally soot free. Is an increase in particulate emissions a price you have to pay for DI?

Kumquat says:

No.

JDMHero says:

Yes, they produce higher particulate emissions. For Europe the A4 comes with port injectors solely for emission reasons. Here in the USA we’re not lucky & get to eat the repair bills.

JDMHero says:

Yes, they produce higher particulate emissions. For Europe the A4 comes with port injectors solely for emission reasons. Here in the USA we’re not lucky & get to eat the repair bills.

FYI, when particulate traps get mandated on GDI cars – I would highly recommend looking into leasing when that happens…

Zack A says:

An extra few MPG is great… until you realize that you have a car with direct injection and a CVT tranny. Direct injection causes carbon build up in EVERY car it’s been deployed in. That’s just a fact. People are having engine tear downs due to carbon build up at as low as 60K miles. CVT trannys are another problem. They don’t last and are very expensive to replace. The only exception are the Toyota and Lexus models. Toyota was smart in that they paired direct injection with port injection. The engine goes through cleaning cycles where it uses the port injection to clean off the valves.
Considering the higher cost of ownership of these vehicles – they completely mitigate any fuel savings and put you in the red compared to a car like the Toyota Camry which still has a traditional automatic tranny and uses port injection. Oh – and it gets 35 MPG too. May not be best in class – but talk to me in 100K miles and let me know how you feel about that CVT and direct injection then.

barry says:

why is it that ALL diesel engines have direct cyl fuel injection and they can last 1 million miles or more with out carbon build up?

JDMHero says:

They don’t. I have a CM871 right now and got rid of a 6NZ C15 with 3 million mi. on it.

The only DI diesel right now is Volvo D13, & the problems are worse than GDI, starting with failures reported at 100k mi., & rebuilds usually in the 400-500k mi. range.

I’d of been bankrupt 10 times over had I bought one 3 years ago. Thank God I didn’t.

JDMHero says:

I wish more people would realize this. On the bright side it’s keeping the auto industry more alive than ever before =)

Wewon Bigly says:

I also wish people realized that it was Obama’s draconian new CAFE ‘54.5MPG by 2024’ regs that forced car companies to implement these flawed designs. They had no choice in order to eek out that extra 1 MPG.

It’s incredible how much destruction Obama has done to our nation. A one man wrecking ball.

JDMHero says:

I don’t want to get into the whole “who was better or who was worser” argument; but if you look at it from the perspective of “Doing your job”, then I don’t argue with having higher restrictions.

If you look at the sheer # of ICE’s in the world and the amount produced each year, you can see that there is a very definite and pronounced problem with the pollution that is being created.

For example, when you look at the pollution in Shanghai, it looks bad, right? Now when you also understand that 95% of autos there are also new and meet the same smog regulations that we have here… “OMG THAT IS BAD WHERE DID THOSE HUGE BLACK SMOG CLOUDS COME FROM???” (<– this should be your reaction)

When you're greeted with that kind of information and realize that the long-term consequence of that pollution is an ever-increasing amount of damage and $-cost associated with crazy weather, which also results in loss of National GDP (For example, when your oil rigs get totaled in the Gulf by a record-strong hurricane); you know you have to do something about it. When you're the POTUS, it's directly your job.

So from this perspective, I understand where the restrictions come from. Am I a fan? Actually yes.

The real issue:
The piss-poor designs and implementations that auto-makers have done to meet these regulations. They need to be ashamed of what they've done, really.

The only people who have done DI right are toyota with D-4S technology, as it holds up the efficiency benefits of DI while also meeting the emissions requirements needed (no particulates). They are honestly taking a hit to their profit margin by selling you 2 fuel systems, when they could just as easily only build in one, stiff the planet, and line their pockets with the savings. Honestly, hats off to Toyota here!

Audi's close; but with a solution that is EU-market only – they literally are at the bottom of the scum-bag bucket because they are clearly prioritizing profits there by witholding an emissions-related solution to the market where they absolutely have to have it in.

Wewon Bigly says:

Way too much to respond to here. You’ve clearly made up your mind that government is good and corporations are bad.

So you really believe that car manufacturers are sitting on some magical new technology that will give infinite amounts of MPG, but would rather use technology that’s known to cause expensive problems? If so, no point in discussing further.

As far your statement that Shanghai’s pollution is coming primarily from cars with our same EPA regs– If that were true, our cities look like Shanghai. No, rather, their pollution is coming primarily from old tech coal burning plants and other industrial pollutants.

Lastly, it’s hard to “motor happily” when I now know my brand new engine is already getting dirtied and will need regular expensive maintenance every 20k or so to keep running in top shape. At least I’m informed now and will be watching closely for cars that come with dual injectors. Cheers.

barry says:

guys diesel engines have been using direct fuel injection for ever. the engines get 1 million miles or more before they have any problems. the valves do not have carbon build up. yes they all have PCV systems.

starskeptic says:

You apparently have never heard of Google…

barry says:

Google? is that a fuel system problem? I have never heard of the engineering term.

starskeptic says:

Houston, we have found the problem…

JDMHero says:

Plz see my reply below. Have you ever even read any literature describing how diesel operates even?

+1 to starskeptic – you’re much more subtle than I would be =)

DLW says:

I have two 08 Cadillac STS. One is a V and one is a 4.6 V8 and both have DI. The 4.6 has 106K and the V has 44K. So far the only problem I’ve had was the alternator failed on the V. Everything else has been scheduled maintenance. I do run a gasoline cleaner occasionally.

HudiBlitz says:

@ DLW – *Neither* of your Northstar engines has direct injection. Not to flame you, but why would you go through the trouble of posting a comment without knowing that?