(of a plan) to have the opposite result from the one you intended

Her plans to make him jealous backfired on her when he started dating her best friend. 她原本想让他妒嫉，没想到最后他却和她最好的朋友好上了。

(of an engine) to make a loud noise as a result of fuel burning too early

I was woken by the sound of a truck backfiring. 卡车引擎的回火声把我惊醒了。