Today we will address a rather interesting topic, namely injectors. But first let’s explain a little what they are and how the injectors work. The injectors are used for both petrol and diesel engines.
As we realize from the name, the role of these parts is to “inject” or spray fuel into the engine. Until the 1990s, gasoline engines ran on carburetors, but this technology is long gone because it has only disadvantages over an injection system.
Instead, diesel engines worked from the beginning with an injection system either mechanically or more recently mechanically controlled.
After the disappearance of the carburetor, the cars were equipped with injection engines, regardless of whether they used diesel or gasoline as fuel.
Since the advent of this system, it has been continuously improved, starting with mechanical injection, followed by electronic single-point, multipoint, computerized, injector pump or common rail to diesel engines. At the moment, injection is the only method of refueling the engine, also being one of the problems that occur with diesel cars in particular.
Why? Well, gasoline acts as a solvent, so gasoline injectors are much cleaner than diesel ones, considering that diesel is much more oily.
Injectors are the final parts of the entire injection system. The injector is a part that corresponds to the number of pistons in the engine, for each cylinder being necessary an injector.
The injectors can be of several types, from simple injectors to aspirated petrol engines, to injectors with the role of pump as in the case of older diesel engines.
When it comes to cars equipped with a turbine we are talking about a different injection system, we are talking about a high pressure injection system capable of reaching even
500-1000 bar for diesel engines. At the moment, injectors are some of the most complex components of the car, they know when and how much fuel to spray.
More and more brands have started manufacturing injection systems. But the most popular are the electrically operated Bosch, Delphi and VDO, the CR Bosch, CR Delphi, Siemens CR and the injectors made by Denso.
How do these systems work?
Let’s take it by popularity, the direct injection motor of the “pump-shower” type or, by all accounts, the “injector pump”, as the name of the injector says, also acts as an injection pump.
They work like spring syringes that spray diesel when “pressed” or actuated by the camshaft. Explaining in a little more detail, each injector is supplied with diesel by a low pressure pump, and when the “injection” has to be made, the camshaft presses on the injector spring and it sprays diesel into the cylinder.
This injection system is quite simple, for this reason it is also the most reliable. This system also has disadvantages, for example for these injectors regardless of speed, the injection pressure is the same, leading to a low efficiency at high speeds and a fairly high level of noxious substances.
In this case the car computer cannot control the amount of diesel injected by each injector, he only “sees” how much diesel each injector consumes indicating to the driver the consumption or if any solenoid is blocked. So this system is a little older but very reliable over time, withstanding many km.
The common-rail system has a slightly more complicated way of operating, as we realize and from the name of this system uses a “common ramp”. The diesel is simply pulled from the tank by a low pressure pump, which in turn “leads” it to the high pressure pump, which in turn pushes it with the same pressure (equal) in all 4 injectors.
Unlike the above system where each injector also has the role of a pump, in common-rail there is only one pump that sends diesel under pressure to all injectors. This system is “assisted” or guided by several sensors, for example the pressure regulator which is mounted on the “common ramp”.
This system has several advantages, including lower fuel consumption, a lower level of pollutants and higher performance. The big disadvantage of this system is that there are a lot of moving parts, which must be very well synchronized with each other to work properly.
Another disadvantage would be the reliability, which over time leaves much to be desired, especially since the high pressure pump is made of aluminum, which over time thanks to poor quality diesel begins to produce span and clog the injectors and the entire injection system.
What can go wrong with an injector?
Depending on the model of the injector, it can fail in several ways.
The most common injector failures
- the springs lose their elasticity and the pressure at which they open lowers. In this case the injectors will open faster than they should (as if you had changed the feed). So fuel will be injected at a lower pressure and in smaller quantities, which will considerably decrease the efficiency of the engine.
Injector nozzles can be decalibrated or clogged due to calamine deposits resulting from the burning of poor quality fuel. The direction of the “jets” will not be correct which will lead to incomplete combustion.
One reason why the injectors break down would be the fact that most drivers drive mostly in the city, at very low speeds, over short distances, with frequent starts and stops and with a colder engine.
The injectors, at least for diesel, if they are not put to work, even at high speeds, will allow the calamine to deposit, which leads to their clogging.
- also especially with the Delphi injection, the “electrical part” of the injectors can be damaged. Specifically, the “return valve” or “control valve” that controls the return of diesel to each injector. Practically it no longer copes with the pressure, and no longer opens and closes the circuit, so all the diesel will go back on the return valve.
Bad injector symptoms
As symptoms in this case would be primarily a drastic decrease in engine power, followed by the appearance of black smoke on the exhaust and a heavy cold start.
Newer generation cars and not only those that use a common-rail injection system, will warn you when something goes wrong with the injection system by lighting a warning light on board.
Usually the “check engine” warning light comes on, then the acceleration is “cut off”, or rather the car enters “limp mode” or “safe mode” and if the situation is worse or has worsened along the way then the computer will stop the car’s engine
Symptoms of a bad diesel injector
An engine remains in good condition as long as what is pumped into it is what is needed and it is done properly. With this in mind, you should always be aware of the symptoms of problems with your vehicle’s diesel injectors.
1. Inconstant power
If the injector is dirty, it can provide the engine with inconsistent fuel levels and consequent inconsistent power levels. The most obvious symptom here would be that the engine rotations would change unexpectedly and the RPM would fluctuate.
2. Engine failures
This problem is usually the result of low levels of fuel that is pumped into the engine when ignited. These failures can be caused by a lot of other problems, including a dirty, clogged injector or an injector that does not open.
3. Slow oscillation
If the engine uses different levels of idle speed, it is probably due to a faulty injector. A dirty injector can affect the rhythm of the injector and can create an uneven spray pattern.
4. Smells of fuel
If you smell fuel, it means diesel is leaking somewhere. This could be due to a faulty injector, a malfunctioning injector valve, which allows diesel to drain from the injector even when it is not active.
5. Higher fuel consumption
Many of you may not know this, a faulty injector can increase fuel consumption. If you think the car has consumed more diesel than usual, even if you were driving at high speed, then the problem may be with a faulty injector.
Symptoms of bad petrol fuel injector
Fuel injectors are vital in the operation and driving of a vehicle. You should take the car to a professional if it shows one of the following signs.
1. Motor vibrations
The injected fuel helps the combustion process. When one of the injectors is bad, the corresponding cylinder will not be able to burn the fuel, this causes the engine to vibrate while driving. Engine vibration is one of those symptoms of a faulty injector, but the cause could be another problem with the engine. You need to make a diagnosis to make sure that the main cause is a faulty injector.
2. Check Engine light on board
If the engine “check engine” lights up on the dashboard after vibrations occur, then there is a good chance that the main problem is a faulty injector. The engine control unit (ECU) will illuminate the warning light on board if it finds that the problem is with a bad, dirty or blocked injector.
3. Fuel leaks
Due to age, an injector may be damaged, resulting in fuel leaking from the injector. A visual inspection can make this clear to you, if you find traces of petrol on the surface of the injector it means that it is damaged.
4. Smells of gasoline
A chain reaction of fuel leakage will also be the smell of gasoline. If the injector does not work properly, then the fuel will not burn. The smell of gasoline should be a serious cause for alarm, so it would be good to diagnose this problem as soon as possible.
5. Emission test failed
Symptoms of a faulty injector also include excessive emissions due to incomplete or irregular burning of gasoline. An injector leak can cause the air / fuel ratio to be so rich that the catalytic converter (catalyst) burns.
How can we properly maintain the car’s injectors?
We can prevent injector wear by using a higher quality fuel, or once in a while to add diesel ourselves. In car shops, we find bottles with solutions for cleaning the injection system.
These solutions are not so expensive, especially since they should not be used too often, but at the same time it is not known how useful they are. The opinions of drivers who have used such solutions are divided, some say that “they worked wonders” and others said that “it only gives you a placebo effect” is nothing “serious” about this type of solution.
Another method of maintaining the injectors would be periodic ultrasonic cleaning. This operation involves removing the injectors from the car engine.
After being taken off the car, they are mounted on a special, very modern bench that uses state-of-the-art technologies to clean the injectors. (jets of solvent solutions at high pressure, ultrasound, etc.). This operation is not so expensive maybe reaching 2 pounds per injector
New, used or reconditioned injectors?
Injectors are quite expensive parts if we want to buy them ourselves. Ideally, we should buy them, why? Well, we still have the option to buy them from dismantling, but we are not sure if they are in good working order, or if they are in good working condition and they have a number of km, so they will not last too long.
Another “middle” option would be to recondition them, an operation that if performed in a professional service, would be a very good option, but if you restore them to the “corner of the block” then do not have high expectations.
Keep in mind in such cases that a defective injector can damage the engine very badly, for example a defective injector can melt the piston, an irreparable defect, being necessary to change the whole engine. So if your budget allows, it would be best to replace the defective injectors with new ones, but if the budget is lower then it is best to turn to a professional service to take care of repairing the injectors.
Never try to recondition the injectors at home following videos on youtube,since it is a silly thing to do, and you risk permanently damaging the injectors or worse damaging the engine.
Even if it costs a little more, always turn to a specialized service. And don’t forget to change the injector rings after you take them off, otherwise they will “blow” or drop compression next to the injectors.
So if you notice something strange in the behavior of your car, such as low power, cumbersome starting or black smoke on the exhaust, then it would be best to check your injectors or go to a service to see how things are.
If you have some knowledge of mechanics, you can do a simple test at home yourself with which you can figure out the condition of your injectors. Go to the pharmacy and buy 4 large syringes and 4 infusion hoses. Then connect the return of each injector to a syringe via the hose.
You start the car and let it idle for about 30 seconds - 1 min. During this time the syringes should not be filled if the injectors are in good condition. If the injectors have problems then the syringes will fill up quite quickly (max 10 sec). This is the simplest test with which you can figure out the condition of the injectors.