What can happen if firing order is incorrect?

When the firing order of an engine is incorrect, one significant consequence is that the engine may backfire through the carburetor. This occurrence can happen due to the improper sequence in which the cylinders ignite their fuel-air mixture. When the timing is off, it's possible that some cylinders may fire at inappropriate times, leading to incomplete combustion and a buildup of unburned fuel in the intake manifold. This unburned fuel can ignite unexpectedly, causing a backfire.

Backfiring not only indicates that the engine is not operating efficiently but can also result in damage to the intake system and potentially other engine components if it occurs frequently or with a significant force. This highlights the critical nature of maintaining the correct firing order for optimal engine performance and efficiency.

Other options, such as engine stalling, can occur for various reasons and are not solely attributed to firing order issues. An engine running smoother or showing improved fuel efficiency are outcomes that are generally desired but not typically associated with an incorrect firing order; rather, they result from proper tuning and functioning of the engine.