When your new tractor isn’t so new anymore, you may notice performance issues with its Tier 4 diesel engine. The cause usually isn’t the engine itself, but deposits that are fouling fuel injectors.

High pressure common-rail (HPCR) direct injection technology operates under extreme temperatures that breakdown standard #2 diesel into carbon deposits, which leads to reduced performance and even engine damage. These deposits can occur in two places. Conventional deposits form on the nozzle body tip. High pressure fuel injector (HPFI) deposits form inside the injector on the needle nozzle and in the diesel metering valve.

Tier 4 engines were phased in from 2010 through 2014 as part of an EPA demand for fewer emissions. However, Tier 4 engine designs create special challenges for diesel fuel quality as equipment ages. Power loss, hesitation, poor fuel economy and shorter fuel filter life are telltale signs of internal diesel injector deposits (IDID) that could lead to injector failure and expensive repairs.

Tier 4 engines demand a lot from diesel fuel. To achieve cleaner burn and efficiency that meets emissions standards, common rail (HPCR) fuel injector systems use tight tolerances to send a fine mist of fuel from the injector into the cylinder. High pressure causes high temperatures (400 to 500°F) that can cook fuel in injectors, causing the fuel to break down and carbonize (coking), which leads to injector tarnishing and IDID.

Nozzle coking, or deposits in the injector tips, has been an issue for years. Injector nozzles spray microscopic fuel droplets and become clogged by the smallest deposits. Even a stain or varnish clog can lead to decreased power and fuel efficiency.

“Tolerances inside Tier 4 fuel injectors are 1 to 3 microns. A red blood cell is about 8 microns wide,” says Chuck Hamilton, technical services manager, CHS. “With tolerances that small, even a stain or tarnish on an injector’s components can cause significant power loss.”

Hamilton says problems can include sticking diesel metering valves or nozzle needles that keep injectors from opening and closing properly. The result is poor starts and over-fueling, which can lead to poor performance of the injection system.

What’s Behind High-Tech Fuel?

The right fuel choice can help avoid these problems. “Standard number 2 diesel may seem economical, but breakdown under high heat and pressure can take a toll on modern engines,” says Rocke Weaver, regional manager with Innospec Fuel Specialties, which formulates premium diesel fuels for CHS, including Cenex^® Ruby Fieldmaster^® and Cenex Roadmaster XL^®.

Unlike nozzle coking deposits, internal diesel injector deposits form inside the high-precision injectors on the needle nozzle and diesel metering valve. Because these components have tight tolerances, as low as 1 to 3 microns (human hair is 70 to 100 microns thick), even the most minimal deposits can significantly reduce power and fuel economy and, in some cases, result in injector failure.

“Premium fuels contain the right ratios of aggressive detergent components and anti-foulants to avoid fuel coking and keep fuel systems performing optimally,” says Weaver. “Premium fuel burns cleaner, prevents IDID and improves fuel pump lubricity.

“We work closely with engine and injector manufacturers, plus thousands of hours of field testing to show how premium fuel additive formulations stand up to heat inside Tier 4 diesel engines. The bottom line is that farmers should be sure they are using  high-performance diesel fuel that contains additional additives to help maintain newer engines.”

Field Performance

Beyond engine longevity, premium diesel fuel improves performance. “Field tests show improved fuel economy of as much as 5 percent and improved power of as much as 4.5 percent with Cenex Ruby Fieldmaster,” says Hamilton. “Fuel lubricity is improved by 10 to 15 percent. Farmers have told us the response to upgraded fuel is nearly immediate. They get noticeably better performance after running just a tank or two of premium fuel. The right fuel detergents can clean early-stage varnish buildups to improve performance and prevent further varnish and IDID.”

In addition to making good fuel choices, a warranty on engine life can offer peace of mind. According to Hamilton, the Cenex Total Protection Plan^® covers costs, including installation and labor, to repair or replace parts that fail during normal use, as long as Cenex lubricants and fuels are used exclusively. The program covers new equipment for up to 10 years or 10,000 hours, or used equipment for up to 8 years or 8,000 hours, with no deductible. Find details at cenex.com/tpp.