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About Fuel Injection
Fuel injection is a sophisticated system that controls the delivery of the fuel. It can be found on almost all new cars currently produced. The reasons why modern everyday cars are being fitted with fuel injection are.
- Lower Levels of Pollution
- Increased Performance
- Lower Fuel Consumption
What do injectors do
Injectors are designed to deliver small, precise amounts of fuel into the engines inlet manifold. To accomplish this, fuel is forced into the injector and a measured delivery is sprayed out through a nozzle that may be as small as 0.002 of an inch. The valve may only be open for a period of 2 milliseconds.
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What types of injector are there
There are 2 types of injectors. Mechanical and Electronic. Mechanical injectors are nozzles that spray fuel continuously into the inlet manifold. The fuel is delivered to them by the fuel distributor head, that also determines both the fuel pressure and volume of fuel delivered. Electronic injectors are electrically operated valves. The quantity of fuel delivered is determined by the cars ECU. The ECU reads information from various engine sensors and calculates how long to hold the injector open. This can vary between 2 - 15 milliseconds on standard production cars.
What can happen to injectors
Problem occur when the chemicals, lacquers and varnish in the various fuels, contaminate the injector. This build up can occur inside the body of the injector, on the pintle valve, the pintle head and seat and also in the filter basket. Chemical contamination and dirt in the fuel system can cause a build up inside the fine screen of the filter basket, restricting the fuel flow rate. It has been shown that a varnish layer as fine as 5 microns on the pintle can restrict fuel flow by as much as 25%. Contamination deposits will alter the shape of the injectors spray pattern The head of the injector pintle is ground to a specific shape, with a tolerance of up to 0.00004 of an inch. It is critical that these spray patterns are correct. Deposits on the pintle will change the shape of the spray pattern, from a fine atomised spray, to a spray that is the wrong shape, or a spray that has thin jet liquid streams, that will not burn properly. Both of these contamination's will create a driveability problem with the car.
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 Symptoms of injector problems
Lack of Power - the vehicle has lost its performance.
Poor Fuel Economy - vehicle uses excessive fuel.
Excessive Exhaust Emissions - vehicle fails the MOT test.
Hard Starting - the car is difficult to start hot or cold.
Rough Idle - the car does not idle smoothly.
Poor Driveability - the vehicle suffers with hesitation and pinks.
What can I do about these injector problems
The minimum life expectancy of an injector is, 1 Billion pulses, well within the life expectancy of the car. The normal approach from main dealers is to replace them. This is a very expensive method of solving the problem, as the injectors can cost between £50 - £200 each. Injectors do not have to be replaced. They can be cleaned both inside the fuel passage and outside around the seat and pintle head with the ASNU Ultrasonic Injector Cleaning and Testing Bench.
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What are the results like
Tests have shown that 97% of injectors will respond to the ASNU method of cleaning. The small percentage of injectors that will not respond to cleaning will have either mechanical damage to the pintle or some internal component like the pintle return spring, or electrical damage to the solenoid windings. The biggest failure of injectors is RUST, caused by water contamination in the fuel system. To determine whether the injectors are working correctly they must be tested for LEAKS, SPRAY PATTERNS, and FLOW RATES over a range of engine speeds and millisecond injector opening times. After cleaning, the injectors are tested again.
What alternative cleaning methods are there
There are various options available, some are tank additives, some are on car cleaning, but none can match the results that ASNU can offer. Only with off the car system cleaning, such as used on the ASNU, can the final results be seen, measured and compared with the pre clean Flow Rates and Spray Patterns.
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