Direct-injection engines improve performance and save fuel, but at a price

It is often touted as the automotive ultimate goal, the ultimate marriage of better overall performance and greater fuel economy. It is the direct-injection (DI) motor, the latest technology designed to press more mpg out of vehicles. And it has actually been providing results.

For example , the Mazda3’s combined fuel economy jumped through 28 mpg in 2010 in order to 32 mpg in this in our testing of the brand new Skyactiv engine. Other automakers have been using direct shot to add horsepower-the Cadillac CTS, for example , gained 34 hp-without any sacrifice in gas efficiency.

Though direct injection happens to be seen mostly on luxurious vehicles or on popular cars as a higher-trim choice (priced anywhere from a few 100 dollars to a couple of thousand), it could soon be inside the means of more drivers because costs continue to come down.

However those engines are also getting reliability problems, something that automakers are trying to keep quiet.

Unsurprisingly, a number of readers have requested us about direct injections. Take Anestis Halkidis associated with North Kingstown, R. We.:

“I have a 2006 NOVA GLI with the 2 . 0T FSI engine with immediate injection, ” he published. “At around 80, 000 miles, I went to the actual VW dealer to identify a check-engine light. As it happens that the intake valves needed to be cleaned due to carbon build up that were causing drivability problems. ”

When his seller failed to offer free function or any compensation, Halkidis required his car to a nearby VW shop that washed the valves by blasting them with walnut shells. (Yes, walnut shells; it’s a technique used by BMW. ) The price to Halkidis was regarding $400.

So what’s plan direct injection?
First, the primer on how it works: Through injecting gas­oline at ruthless directly into the engine’s ignition chamber, direct injection much more precisely measures fuel compared to conventional fuel-injection systems or even old-time carburetors.

The result is a lot more complete combustion and chillier cylinder temperatures that allow a higher compression ratio with regard to greater efficiency and energy. Engine technology supplier Bosch says that direct treatment can return a fifteen percent gain in gas consumption while boosting low-end torque as much as 50 percent.

Combining primary injection with other technologies-such since turbocharging-can deliver even greater benefits in economy and performance. Which in turn enables carmakers to make use of smaller displacement engines, leading to an efficiency snowball effect. Numerous automakers are marketing DALAM as pro­viding fuel economy that is almost as good as a hybrid’s, and with better performance-but with no $4, 000 hybrid high quality.

Although the breakthrough seems like ideal come true, an unwanted side-effect has been emerging. Letter authors have complained to Customer Reports and the National Freeway Traffic Safety Administration (NHTSA) that over time DI can result in clogged fuel systems as well as engine carbon buildup. The end result can be engine hesitation along with a loss of power-and the need for costly repairs.

Some carmakers, such as BMW and Kia, possess issued technical service programs (TSBs) to their dealers suggesting that drivers use only name-brand detergent gasoline-without ethanol additives-and that they periodically add a fuel-system cleaner when they refuel. (A TSB is an alert that this automaker sends to sellers to warn about continuing problems with individual models and how they can fix them. It may allow retailers to make repairs at little if any cost to the customer like a goodwill gesture. )

Some other automakers have devised a good engineering fix that works as the car is oper­ating. It requires modifying the engine to be able to spray a small amount of fuel straight onto the valves to keep them clean.

It’s vital that you note that not all cars along with direct injection experience extensive problems. But if your engine stumbles more than it used to, or perhaps it suddenly lacks strength, ask your dealer about this. A fix may be accessible, and you may not have to pay for this.

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