What Causes Backfire in the Exhaust Pipe?

[DiJayden]

Backfire in the exhaust pipe is caused by insufficient fuel supply and an overly lean air-fuel mixture. When the mixture is too lean, the combustion speed slows down, continuing until the end of the exhaust stroke when the intake valve opens. The fresh air-fuel mixture then ignites upon contact with the unburned exhaust gases remaining in the cylinder, flowing back through the exhaust pipe and spraying out from the intake port, resulting in backfire. Below is a detailed explanation: 1. Explanation One: The ignition timing advance angle is a crucial parameter for engine operation. The size of this angle directly affects engine performance. Typically, high-performance engines use secondary injection technology during cold-start fast idle conditions. 2. Explanation Two: Most engines employ various technologies such as variable valve timing or variable valve lift, with similar basic principles. These systems primarily adjust the timing or valve opening angle according to different engine operating conditions to achieve optimal performance.