Fuel Injectors

The main causes of fuel injector wear or failure is contamination of the fuel system and corrosion due to moisture in the fuel. Injector performance can be affected by particles as little as 10 microns (0.01mm).

Replacement benefits, compared to worn fuel injectors:

• Restore original spray pattern
• Improve fuel mixture formation resulting in improved overall vehicle performance
• Reduce rough running caused by non uniform spray dynamics

What about re-manufactured injectors?

Re-manufactured injectors as they are commonly known are just second hand injectors that have been cleaned in an ultrasonic bath, fitted with a new strainer and o ring. Before choosing between new or reconditioned injectors consider the following points:

• Ultrasonic cleaning only cleans the nozzle tip and does not clean the inside of the injector
• Ultrasonic cleaning does not clean any rust or corrosion within the injector, which if present will lead to premature injector failure or poor spray patterns
• Modern style injectors, such as EV6 are of similar price new as ultrasonically cleaned re-manufactured units. Why would you buy second hand?

Why choose a new Bosch fuel injector?

• Bosch is the worlds leading supplier of fuel injectors as original equipment
• Broad market coverage for OE and after market applications

Bosch fuel injectors are competitively priced and sold through leading automotive part stockists. Please see our 'Dealer Locator' at the top of the page to locate you local store.

Purpose and Function.

Fuel injectors perform an important role in the accurate metering and atomization of fuel. These electro-mechanical valves react in milli-seconds to open and close giving the electronic control unit optimal control over fuel flow to the engine.

Method of Measurement.

Fuel flow specifications are given in grams per minute, as this is an internationally accepted standard at vehicle manufacturing level. As vehicle development engineers deal with the weight or mass of air inducted by an engine not its expected power rating, the weight of fuel that an injector can provide is the pivotal measurement. Bosch does not rate fuel injectors related to expected engine power outcomes for this reason.

Power Ratings of Fuel Injectors. [Horsepower]

It has become an aftermarket performance industry practice to rate fuel injectors in relation to expected engine power outputs, mainly Horsepower.

As this method of measurement has many issues in relation to various calculation methods, accuracy, individual interpretation and overall relevance, Bosch as an Original Equipment supplier of fuel injectors, does not subscribe to this specification method. 

There are many design requirements taken into account when undertaking the design and manufacture of a fuel injector to suit a particular application. Further explanation can be found under the "Method of Measurement" heading in this section.

Effects of Fuel Pressure on Pintle Type Fuel Injectors.

Fuel velocity through a pintle type fuel injector [type code EV 1] can dramatically affect its ability to atomize fuel. The profile of the pintle used in a fuel injector has a direct relationship to the operating pressure it is designed to operate under. Whilst Bosch produce various fuel injectors that may flow the same amount of fuel at a given specification, the system operating pressure will influence the pintle profile. Correct pressure will result in a well atomized spray, while insufficient pressure will result in a "hosing" effect. Excessive pressure will result in either "hosing" or a spray angle that is too large for the targeted area dependent on the pintle profile.

The consequence of excessive fuel pressure on a pintle type injector may well be that as the pressure is increased the mixture values of the engine may appear to get leaner. This is of course not the case, but the fuel being injected is no longer atomized and is entering the cylinder as a liquid mass. This will typically cause the Hydrocarbon [HC] values to rise due to the raw fuel exiting the cylinder, and the Carbon Monoxide [CO] to drop due to insufficient combustion.

Later design fuel injectors [type code EV 6] use "director plate" multi-orifice technology to better atomize fuel across various operating pressures. These injectors allow more flexibility in relation to operating pressures without compromising spray efficiency or fuel atomization.