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Your Fuel injectors worn out? » Read more about common malfunctions • Repair • Replacement manual
Injector nozzles & fuel injectors: finding and repairing defects
The injector nozzle, also known as fuel injector is an important part in petrol and diesel engines with direct injection. For both engine types the injectors are the last station for the fuel before its injection into the combustion chamber where it is ignited. Due to their delicate construction and high temperatures occurring, injectors are prone to wear and need replacement. We show you how to recognise defective fuel injectors and injection nozzles and offer tips on replacement.
Defective fuel injectors: these are the symptoms
Several symptoms indicate a defect of one or more injector nozzles. Not every symptom is specific and therefore other damage should be considered as well. Several symptoms occurring simultaneously is a definitive sign of an injector defect. These symptoms are:
- increasing emission of harmful substances (identified on occasion of exhaust emission check)
- increased fuel consumption
- ignition errors and failures
- loud knocking noise coming from the engine compartment
- obvious performance impairment without recognisable cause
- dark-coloured or blue exhaust when starting the engine.
Replacing just one or all fuel injectors?
Only replacing the malfunctioning injector poses no problem; yet it makes sense to check the other components thoroughly as well. If these are visibly worn or dirty, replacing all injection nozzles and injectors can be worth while, saving yourself the trouble of a new repair when another one of these components fails.
How useful is cleaning the fuel injectors?
Many companies and garages offer professional cleaning of the injection nozzles and fuel injectors. These solutions only make sense for older cars ,where easy and thorough cleaning is possible. Modern injector nozzles or Piezo injectors are difficult to clean. Costs often exceed the expense for a spare part. Replacement is often the better option. Nevertheless, cleaning and freeing modern injectors from dirt and deposits is possible. If this is successful and no mechanical damage done to the injectors, this solution can turn out to be economically feasible.
Replacing the injector nozzle step by step
Unfortunately we cannot offer a detailed manual for replacement of the fuel injectors. The reason lies in the fact that the procedure greatly varies, depending on engine type and manufacturer. Several special tools are required and upon installation the fuel injectors need adjustment with help of modern technology to ensure an optimal and regular running of the engine. This exceeds the technical possibilities of most DIY'ers by far. We advise even the most experienced DIY'ers against taking fuel injector replacement upon themselves. In the worst case this can lead to total engine failure. Visiting a garage is always recommended for these components.
DIY replacement: what to observe
If you still intend to replace injection nozzles or fuel injectors yourself, be sure to work cleanly and meticulously. Incorrectly installed or adjusted injectors are bound to cause further damage to the engine and other components. When this happens, the saved expenses will not cover the risk.
These are the costs
The price for new fuel injectors varies according to construction and age of the engine. Generally, costs for a fitting spare part lie between 100 and 340 EUR (± £90 - £305) per piece. The fee for two hours of work should be added for installation in a garage. Consequently total costs for replacement lie between 200 and 450 EUR (± £180 - £400). Therefore, the price for replacement of all fuel injectors is considerable. On top of the material costs between 800 and 1200 EUR (±£715 - £1075) comes the garage fee. All in all be ready to count on several thousands of pounds for total replacement of all injector nozzles or fuel injectors.
