Of the many engine problems that may crop, one of the most damaging ones is backfiring. The term is borrowed from old terminology used for primitive firearms, where occasionally a shot exploded back through the gun breach instead of shooting forward. In modern cars, a backfire is typically an explosion of fuel in the engine's tail end or exhaust mechanism.
What is Engine Backfiring?
Combustion or explosion of fuel that occurs outside the chambers of a car's internal combustion engine, in the exhaust manifold or intake manifold, is known colloquially as 'Engine Backfiring'. This explosion of unburnt fuel typically occurs in a carburetor, exhaust system or air cleaner.
Either unburnt fuel explodes in the exhaust or a spark plug acts before the intake valve is closed, causing an explosion in the induction system itself. The latter types of explosion is rarer in modern cars, which have adequate safety measures to prevent such a backlash.
One clear sign is a loud bang from the car exhaust, which results from the explosion which occurs there. After such an explosion, the performance level of the engine nosedives and you experience loss of power. The engine may just sputter for a while and take time to get back into the groove, before the car moves forward normally again.
A smoothly functioning engine is like a host of musicians playing a harmonious symphony. One note out of line can prove to be its undoing. Just like there are several ways in which a harmony could be broken, there are more than one reasons for backfiring. Here are the most common causes listed for your perusal.
Dysfunctional or Absent Catalytic Converter
It is the job of the catalytic converter to remove the unburnt hydrocarbons from the exhaust gases, besides cleaning out the pollutants.
If the catalytic converter is not functioning or has been removed, unburnt fuel is not cleaned up in the exhaust leading to a spontaneous explosion, which manifests as a backfire through the exhaust system. Repairing or replacing the catalytic converter is the only way you can fix the problem.
Ignition Timing Problems
The most common reason for backfiring is an ignition timing problem, caused due to problems in the electrical wiring of the spark plug. Getting the spark plug mechanism checked might solve the problem in this case.
Engine Timing Problems
Another prime cause is an engine timing problem. When the timing belt goes slack and the engine cycle rhythm goes awry, backfiring might occur. Get the engine timing belt and timing mechanism checked to take care of the issue.
Inadequate Fuel Pressure
A drop in fuel pressure due to leaks in the injection system, dysfunctional fuel pump, dysfunctional carburetor, clogged air filter or bad fuel flow sensor causes a lean or rich air to fuel mixture to be created.
In such circumstances, when the ignition spark is mistimed or the engine is too advanced in its timing, unburnt fuel might explode outside the ignition chamber, leading to a backfiring problem. Get the entire injection system checked to address the root cause of the issue, in this case.
To summarize, backfiring in modern car engines is a result of a lean or rich air-fuel mixture, coupled with engine timing problems, leading to incomplete combustion. All these factors cause fuel to explode in the intake or exhaust, which in turn results into an engine backfire.
Solving backfiring issues is a job best left to professionals. There are several small mechanical problems in the engine intake or exhaust system that may cause it. In case you are facing a frequent backfiring issue in your car, its best to get the engine checked as soon as possible, before an intake valve side explosion causes major damage.
Make it a point to get your intake, as well as exhaust manifold, along with the fuel pressure regulator and carburetor checked from a car service center. Make it a part of your regular maintenance schedule to prevent future recurrences of engine misfiring or backfiring.