Topics:
- Backfire
- Causes
- Consequences
Backfire:
A backfire occurs due to a technical malfunction in a gasoline engine, often equipped with an (older G1 or G2) LPG system. A backfire refers to the ignition of the fuel at the wrong time, for example, when it is still in the intake manifold. If the spark plug fails to ignite the fuel, an air-fuel mixture remains, while the piston has already completed the power stroke. Unburned fuel is thus present in the cylinder, which ignites at another moment due to the high temperature. This can occur when the intake valve opens, causing the fuel to ignite in the intake manifold.
A backfire can occur while driving, during idle, or even while starting the engine. In modern engines with an advanced engine management system, backfires rarely or never occur anymore. A backfire should not be confused with “pinging.”
Causes:
- Incorrectly adjusted ignition: The spark plug cannot ignite the mixture on time because it sparks too early or too late.
- Too lean mixture: The air-fuel ratio is incorrect; there is proportionally too little fuel present to enable ignition.
- Dirty / carbonized spark plug: Due to improper driving habits or prolonged maintenance delay, the spark plug is in too poor a condition to achieve optimal combustion.
- Faulty spark plug wires: The spark plug does not produce a proper spark.
- Converter: Due to a contaminated membrane in the converter of a gas system, it can happen that the gas supply does not stop on time. Gas is then supplied at undesirable moments, which can ignite at high temperatures in the intake manifold. (For clarity; the converter ensures that a gas mixture is made from liquid gas.)
Consequences:
Since the mixture has ignited in the intake manifold, there has been extremely high pressure. This explosion can cause the intake manifold to crack or burst. Additionally, the air intake hose, the mass air flow sensor, and the air filter, including the air filter housing, can be severely damaged or broken.