Fuel Injectors - Diesel Ignition Pressure

Nozzles or nozzles are used to constantly supply the right amount of fuel to the combustion chamber of diesel engines. These small but highly stressed components keep the engine running properly thousands of times a minute. Although they are made from high quality materials, these components are subject to wear and tear. Here you can read how to recognize faulty fuel injectors and how to deal with breakdowns.

Direct injection engine requires pressure

Diesel engines are referred to as "self-igniters". This means they do not require external ignition in the form of a spark plug to burn the fuel. . The compression pressure generated by the upward moving piston is sufficient to cause the desired explosion of the diesel-air mixture.

However, it is important that the correct amount of diesel fuel is injected into the combustion chamber at exactly the right moment in an optimally atomized form. If the droplets are too large, the diesel will not burn out completely. . If they are too small, the engine will overheat or not work properly.

To create this reliable condition, injectors (usually made in the form of a pump-injector assembly) supply fuel to the combustion chamber at high pressure. Average pressure 300-400 bar. However, Volvo has a 1400 bar model.

In addition to diesel engines, there are also direct injection gasoline engines. . They also use fuel injectors.

The structure and position of the fuel injector

The injection nozzle consists of a nozzle part and a pump part . The nozzle protrudes into the combustion chamber. It consists of a hollow pin with hole width 0,2 mm .

A pump is installed at the rear of the same assembly, which injects fuel into the combustion chamber at the required pressure. . Thus, each nozzle has its own pump. It always consists of hydraulic piston, which is reset by a spring . The nozzles are located at the top cylinder head like spark plugs in a gasoline-powered car.

Fuel injector defects

The injection nozzle is a mechanical component subjected to high loads . He is subjected to extremely strong forces on and in him. It is also subject to high thermal loads. . The main cause of defects is coking on the nozzle or inside it.

• Coking is the residue of incompletely burned fuel .

In this case, plaque is formed, which further impairs combustion, making plaque more and more.

Fuel injector defects have the following symptoms:

– Poor engine start – High fuel consumption – Black smoke from exhaust under load – Jerks of the engine

A nozzle defect is not just expensive and unpleasant . If not repaired as soon as possible, serious engine damage can result. Therefore, problems with injectors should not be postponed for later, but solved immediately.

Fuel injector diagnostics

There is a simple and very safe way to check the operation of the engine fuel injectors. . Basically, all you need is rubber hoses and so many cans of the same size how many cylinders are in the engine. The hoses are connected to the drain line of the nozzles and are attached to one glass each . Now start the engine and let it run 1-3 minutes . If the injectors are intact, each can will receive the same amount of fuel.

Faulty injectors are detected by the fact that they release significantly more or significantly less fuel through the drain line.
For such diagnostics, the market offers a test kit for about 80 pounds. Highly recommended as it is designed for that very purpose .

How to deal with defects on injectors

Before reading: injectors are very expensive. For one injector you should consider 220 - 350 lbs. Since nozzles should always be replaced as a complete set, you will have to pay between 900 and 1500 euros sterling for spare parts.

The good news, however, is that at present there are a large number of specialized companies that can restore injectors. This cleans the injector of all deposits and replaces all wearing parts such as seals or clamps.

Then the nozzle is tested and returned to the customer as a nearly new part. The use of remanufactured parts also has big advantage: when installing remanufactured injectors, re-adjustment of the engine control unit is not required . However, for this purpose, it is important to return each nozzle to exactly the position it was previously installed in.

Theoretically, removing the injectors is quite simple. . They don't screw in like spark plugs, but usually " only » are inserted. They are held in place by clips attached above them. However, in practice, things look very different. . To get to the injectors, you need to disassemble a lot of things.

If you expose them and loosen the latches, a car enthusiast is often in for an unpleasant surprise: the nozzle sits firmly in the engine and does not loosen even with the greatest effort . For this, well-known manufacturers have developed special solvents that trigger caking, which is responsible for the tight fit of the nozzle.

However, even when using a solvent, removing the nozzle can be a huge effort. It is important here never lose patience and cause additional damage to the engine.

Always work on all nozzles!

Since all nozzles are loaded almost equally, they wear out almost equally.

Even if only one or two injectors are found to be defective during testing, failure of the remaining injectors is only a matter of time.

Therefore, the most economical way is overhaul of all injectors in the service department . A new nozzle should only be purchased as new when the specialist advises that it can no longer be repaired.

This way you save on high costs and get a perfectly running engine again.

Reasonable extras

With the nozzles removed, the machine is practically immobilized . Thus, this is a good opportunity to move on to further repairs. In diesel engines, it is also recommended clean EGR valve and intake manifold . They also coke over time.

The particulate filter in the exhaust can also be removed and cleaned by a specialist. Finally, when refurbished injectors are installed, all paper filters such as pollen, cabin or engine air filters can also be replaced. . The diesel filter is also changed so that only guaranteed clean fuel gets to the overhauled injectors. Finally, changing the oil for a smooth and clean engine is the last step. , allowing you to calmly start the next thirty thousand kilometers.