The injection nozzle is one of the most important components of modern injection systems. In earlier times, engines still had a carburettor or intake manifold injection, which provided an ignitable mixture of air and fuel. In modern fuel-injected internal combustion engines, on the other hand, the fuel is injected directly into the cylinders at high pressure. Find out now which symptoms occur in the event of a defect, how costs for subsequent repairs can be avoided, and when it is worth changing the injection nozzles.

Function of the injection nozzle in the engine

As part of the direct injection system, the injection nozzle ensures that the fuel always enters the combustion chamber in a finely atomised form and can be ideally ignited. The right amount of fuel is always injected into the cylinder via the injection nozzle. Depending on the engine design, different types of injection nozzles are used. Diesel engines have injection nozzles or injectors, petrol engines also have injection valves.

Signs of faulty injection nozzles at a glance

If an injector is defective or working incorrectly, typical symptoms often indicate this. Since the fuel is only inadequately atomised via defective injectors, signs such as rough engine running are often evident. The engine may also start badly or stop while driving if the injection quantity is not correct.

• Engine runs out of round
• Starting problems
• Fuel consumption is increased
• Vehicle jerks and goes out
• Exhaust gases are discoloured blue or grey
• Car smells of fuel
• Engine knocks or sounds unusual
• Values in the exhaust emission test are poor
• Engine indicator light comes on

Often a car with a faulty injection valve or injector is noticeable due to increased fuel consumption. The check engine light may also illuminate. Unusually blue or grey exhaust gases and a smell of fuel can also indicate defective injectors. Sometimes cars with defective injection nozzles also fail the emissions test due to poor exhaust emission values.

The symptoms should always be observed

If the first signs of defective injectors appear, the car should be taken to a workshop as soon as possible. With diesel engines, it is not uncommon for too much diesel to be injected due to a faulty injector. This in turn can lead to corking, for example in the area of the valves. A defective and dripping injector can cause damage to the piston. In addition to damage to the interior of the engine, too much injected fuel can also damage components such as the catalytic converter.

Causes of problems with the injection nozzles

If an injection nozzle is defective, there are various possible causes. Often, a blockage of the fine nozzles occurs due to contamination. Diesel or petrol of low quality or contamination in the fuel system can be responsible for this. The use of unapproved and unsuitable additives can also lead to problems with the injection nozzles. Often, increasing wear on injection nozzles or injectors occurs with high mileage. Then a change of the injection nozzle or injector is often unavoidable. But a defective fuel pump can also cause broken injectors due to metal chips.

Avoiding faults on the injection nozzle

A faulty injector or a defective injection valve can quickly lead to problems and consequential damage. The costs for subsequent repairs can be easily saved if the car is regularly serviced in the workshop. During a detailed maintenance or a special engine check, every nozzle and injector is examined. It is often possible to clean dirty components, otherwise they are replaced with new parts.

Care and maintenance of the injectors

Vehicles that are regularly serviced in the workshop are less prone to defects. Complications such as defective injection nozzles are also detected much earlier during maintenance. This in turn saves costs for expensive follow-up repairs. Defects in the injection system can be avoided with simple measures.

1. Have the car serviced regularly at the workshop
2. Refuel vehicle only with designated fuels
3. Fill up with good quality petrol or diesel
4. Use additives only if approved by the vehicle manufacturer
5. Do not delay repair and replacement of parts

Regular maintenance of the engine and cleaning of the injection nozzles prolongs the life of the units. However, the symptoms do not always have to be caused by faulty injection nozzles. A defect in the ignition or other defective parts in the injection system can also be responsible for poor engine running, for example. Therefore, inspection, cleaning and replacement of the components are a matter for the specialist.

Repair and replacement of the injection nozzles in the workshop

For the repair, the injection nozzle must be removed and disassembled. The individual parts can then be inspected and replaced with spare parts in the event of a defect. As the complexity of the injection systems increases, the repair of the components also becomes more complicated. Only specialised companies offer the repair of components such as injectors and injection nozzles. Depending on the cost of the repair or a new injection nozzle, it may also be worthwhile to exchange them for new parts. Make an appointment with your workshop to have the engine and injectors inspected.

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