Back-fire

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A back-fire or backfire is the combustion or explosion generated by a running internal combustion engine that occurs in the air intake or exhaust system rather than inside the combustion chamber. Unburned fuel or hydrocarbons fueled in the exhaust system can produce loud noises even if no fire exists in the exhaust. The visible fire may momentarily come out of the exhaust pipe where the exhaust system is shortened. Fire can also travel to air intake piping. Both conditions can cause a loud roar, along with possible loss of power and forward motion. A back-fire is a phenomenon apart from the fire produced by Top Fuel dragsters.

If a boomerang occurs in the exhaust, it's called after-fire . The term boomerang is when unburned fuel moves back into the intake, and burns, while after-fire burns unburned fuel on the exhaust side of the combustion cycle. The probable cause is due to a rich run, which in certain cases can come from burning that does not reach a high enough temperature to burn fuel properly. Mean splashes, coils, or plug cables could be the cause. In many cases, fire after burning, or fire in the exhaust or exhaust system. This over time will cause damage to the muffler and exhaust piping - which eventually leads to exhaust leaks, and a burned exhaust/catalytic converter. There will also be performance lost due to weaker combustion.

Also, an explosion in the inlet hole, carburetor/throttle body, or air purifier from an internal combustion engine may occur when the intake valve is not closed before fuel combustion.

This term comes from parallel experiences with unreliable initial firearms or ammunition, in which the force of the explosion is directed outward at the breech instead of the muzzle. From here comes the use of the word "boomerang" as a verb to show something that produces unwanted, unexpected, and undesirable results.

Video Back-fire

Description

Backfiring in internal combustion engines takes place outside the combustion chamber, and is usually the result of improper air ratios for fuel. An overly lean air fuel mix (ie, overflowing air) can cause failure to ignite in the combustion chamber, also called "shootout". Unburned fuel then enters the exhaust system, where the heat component can cause unexpected fuel to ignite. Alternatively, a rich air fuel mixture (ie overflow of fuel) can cause incomplete combustion, again causing unburned fuel to enter the exhaust system.

Boomerang can also occur before the combustion chamber. One of the causes is timeliness. If the time is too early, the spark plug fires before the intake valve closes, causing combustion to propagate into the intake manifold, further fueling the fuel-air mixture there; the resulting explosion then moves out of the carburetor and air filter. In many small marine engines, the screen is placed above the carburetor intake as a flame retainer, to prevent this flame from coming out of the intake and potentially triggering fuel or fuel vapor in enclosed spaces or boat hulls, causing fire or explosion. Alternatively, the ignition timing may be late, in which case the combustion is not completed when the exhaust valve is open, allowing the combustion to spread to the exhaust system.

In addition, improperly adjusted carburetors that create slender conditions during acceleration can cause the fuel-air mixture to burn so slowly that combustion still occurs during exhaust strokes, and even when the intake valve is open. The front of the fire can then increase the intake and cause a boomerang. In this situation it is conceivable that there is a boomerang that occurs in the intake manifold and exhaust manifold simultaneously.

In both cases (burning occurs before and after combustion chamber), the result is a sharp pop, which is referred to as a "boomerang" daily. However, to overcome the problem, the mechanics of the machine more strictly defines the ignition of the fuel in the system exhaust engine as "afterfire", while the "boomerang" is the same process that occurs in the induction system.

Maps Back-fire

Cause

The boomerang exhaust system occurs on machines that have an emission system malfunction, such as the airway injection system valve problem, exhaust leak, or when the catalytic converter has been released. In some high-performing vehicles, when the driver shifts up and off the accelerator, the engine has a rich moment. This causes an incomplete burn that causes smoke to explode in the exhaust system along with the sound of explosions or sound booms. This is the result of work equipment, and it is not possible to cause damage.

Fuel injected engines can backfire if there is a leakage of intake (causing the engine to run lean), or fuel injection components such as faulty airflow sensors.

Common causes of boomerang are:

• Bad or irregular timing of the engine time is often the cause of a boomerang, but it can also cause the exhaust to backfire. Boomerang and loud explosive sounds are common when anti-lag is on
• An improper cable in the ignition key can also cause timing and boomerang issues
• Low fuel pressure, clogged fuel filters, and weak fuel pumps can cause severe slim air-to-fuel ratio during fuel injection
• A lost or damaged catalytic converter can cause a boomerang out of the exhaust

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Apps

With older engine designs, backfiring can be common or unavoidable. Boomerangs are rare in modern vehicles with fuel-injected and computer-controlled fuel mixtures.

In a drag race, the boomerang in the intake usually results in total destruction of the intake manifold, carburetor, supercharger, and sometimes engine.

Cars with sports exhaust (both factory fitting and aftermarket) are much more likely to backfire. In some circumstances, the boomerang is seen as an additional addition to the car. The TVR Cerbera is an example of a sports-exhausted car equipped with a factory that often backfires engine braking.

In high-powered supercharged piston engines such as Rolls-Royce Merlin and Griffon, backfiring into the inlet manifold is prevented by a fire trap inside the manifold, the trap prevents the flame from spreading to the compressed air/fuel mixture in the manifold.

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Accidentally created

Tanks and ships can use special fuel or "oil mist" injection into the drain to create a smoke screen. Instead of burning, the oil usually evaporates and condenses back to a certain droplet size, but in abnormal conditions it may burn or even produce a thermobaric explosion.

Cars that are extensively modified for visual display rather than street use (stunts, commercials, films, etc.) Can be fitted with gasoline injectors in the exhaust system, or even with a small fire thrower separate from the exhaust.

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See also

• Diesel, condition after run where machine keeps running without trigger spark plug
• Ignition timing
• Valve time
• Anti-lag

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References

Source of the article : Wikipedia