One of the most common mechanical problems that will happen with cars today is that they have fuel injectors that have become dirty and clogged.
When cars have fuel injector faults they will exhibit problems starting or they will run in a very ragged and rough fashion. Some of them will misfire and idle roughly before smoothing out. This is very common as cars age and start racking up high miles, but can also occur if you have a car that is left to sit for long periods of time.
While the modern fuel injection system has transformed the way engines start up in cars this system does have some built in design points that have to be watched and maintained to prevent problems. Today almost every automobile engine will start up when the ignition key is turned to the on position.
When this occurs, the fuel injectors spray a fine mist of fuel into the runners of the intake manifold, which creates an immediate vaporization of the fuel spray. This must occur because liquids cannot be used to power your engine, only the vapor that is produced will burn. The spray pattern from the injectors must be an extremely fine mist. The lighter and finer the particles that are contained in this mist, the easier it is to be turned into burnable vapors. When your engine has dirty fuel injectors they cannot spray a fine, evenly distributed pattern of mist.
Sometimes the injectors will spray more fuel in only one direction, or the spray may be more of a drip or a thick stream instead of the fine mist that is needed. The spray of fuel from the injectors may also come out continuously if they are not able to close off completely.
If you have an automobile that refuses to start, it may be due to fuel injectors that are stuck and unable to open at all. With cars that are running roughly and have cylinders that are misfiring, the problem may be traced to an uneven air-fuel mixture to for the cylinders. This means that some may get too much or too little of the necessary fuel and this creates problems in the overall firing cycle.
Misfiring with cylinders means that the available oxygen they contain is not being used for combustion purposes. Instead, the oxygen is being pushed out of the exhaust pipe on the next exhaust stroke.
On cars today, there are computerized oxygen sensors that measure and track this unused oxygen and this will cause the computer to react as if the engine is running extremely lean. What happens then is that the computer that controls the fuel injectors will attempt to compensate by adding more fuel to all of the cylinders by keeping the injectors on for longer periods of time.
This situation then causes even the cylinders that receiving the right amount of fuel to get too much fuel, which will make them, begin to seem too rich. Now the system that was supposed to correct the problem has mistakenly overcorrected and has made the operation of your engine worse than before. This will continue to deteriorate until you fix the original culprits, which are the dirty fuel injectors.
Since fuel is supposed to be clean and there are additional filters that are in place throughout the vehicle’s fuel system to trap impurities like dust and dirt particles it seems hard to understand how the injectors can get so filthy. Usual fuel filters are made to trap particles that are between 10 - 30 microns in size.
To show you what this size means, you should know that a single micron is only a millionth of an inch in size. So you can see that these filters are busy trapping lots of particles. They can even get overloaded themselves, but ordinarily they can keep most dirt out of the injection system. Still liquids can carry very small impurities through a filter.
At slower engine speeds, you will not have a great deal of fuel that is coming through the fuel injectors and sometimes there are very small particles and impurities that might become lodged in the small valves contained in the tiny nozzle tips that release the spray. Drivers may find that a few revs of the engine with the foot feed can flush these deposits out.
There is also a problem with the injectors sticking or becoming dirty from the residue deposits that normally build up in the spray nozzles. After an engine is shut off, the fuel evaporates on the tip of injector nozzles. The tops of the nozzles will be the first to experience the evaporation process, which will leave a sticky residue behind. You may be able to rev and run the engine for a few minutes and flush some of these deposits away, but usually a little chemical cleaning help is your best bet.
Drivers often notice that gas companies advertise the fuel-cleaning additives included in their products. There are some fuels that contain more additives that can run more cleanly than regular fuels. This will also help keep the injectors clean, but almost all gasoline products have at least some of these clean fuel additives.
You can purchase a variety of additives that will clean your fuel and clean your fuel injectors if you follow the directions carefully. Usually you will use a container of one of these products to a tank of gas, do not add more than is called for and do not use it any more frequently than is advised. If you do so, you can actually break down many of the rubber components in your car’s fuel system. Mechanics can also clean the fuel injection system for you.