What is the difference between backfire and afterfire?

[OEllie]

The difference between backfire and afterfire is: backfire occurs in the intake system, while afterfire occurs in the exhaust system. The following are the causes of engine backfire: 1. Slow combustion of the air-fuel mixture. 2. Incorrect ignition sequence. 3. Low battery voltage. 4. Faulty coolant temperature sensor or air flow meter. 5. Excessive ignition advance angle (this is very important). 6. Incorrect valve timing. 7. Excessive carbon buildup on the valves. 8. Incorrect ignition sequence. 9. Faulty spark plugs. The following are the causes of engine afterfire: 1. Dirty or clogged filter. 2. Impure gasoline quality. 3. Insufficient ignition advance angle. 4. Incorrect valve timing. 5. Faulty air flow meter. 6. Insufficient spark plug breakdown voltage. 7. Incorrect ignition sequence.

[Joshua]

Backfire and knocking in car engines really show different symptoms. I remember when backfire occurs, it sounds like popping combustions in the exhaust pipe, as if there's an issue with the ignition system—maybe aged spark plugs or incorrect air-fuel mixture causing unburned fuel to detonate in the exhaust. Knocking, on the other hand, sounds more like pistons hitting the cylinder walls internally, with a thumping noise, usually caused by loose pistons or detonation, potentially damaging piston rings. Experienced drivers know backfire often happens during cold starts, while knocking becomes noticeable at high RPMs. Don’t underestimate these noises—they’re warning signs of engine trouble. Check ignition timing or replace spark plugs promptly to prevent worse damage.

[LeRylee]

I'm quite familiar with the difference between backfire and piston slap: backfire refers to the noise caused by detonation in the exhaust system, mainly triggered by ignition delay or valve leakage leading to unburned fuel explosion; while piston slap indicates the knocking sound from pistons, often caused by worn piston pins or excessive combustion pressure. My driving experience tells me that backfire noises mostly occur during acceleration, whereas piston slap is more noticeable during steady-speed driving. I recommend regular checks of the air-fuel ratio sensor and spark plug gap, as these can prevent most issues. For safety, if engine abnormal noises persist, it's best to pull over to avoid engine overheating and visit a repair shop as soon as possible to prevent disruption to daily schedules.

[CamilleAnn]

When driving, encountering backfire is the popping sound caused by combustion in the exhaust pipe, often due to excessive fuel injection or ignition timing issues. Piston slap is a similar knocking sound from the piston hitting the cylinder wall, creating a loud bang when the piston is loose. I recommend checking if the spark plugs are dirty; cleaning them can help improve the situation. Regular maintenance can prevent most issues.

[DelAllie]

The sounds of backfire and knocking are different: backfire comes from the external exhaust system's combustion, resembling a cannon shot; knocking is the internal piston or connecting parts' impact sound. I think it depends on the ignition system's condition—old spark plugs can easily trigger backfire, while worn piston pins can cause knocking. During repairs, first use a diagnostic tool to read fault codes, then adjust the air-fuel ratio or tighten components accordingly. From a safety perspective, frequent noise can accelerate engine wear, so it's best to check the filter and oil pressure once a month.