Sienna Hybrid Engine Misfire

Combustion misfires, eh? That's not fun, but pretty common. Since it's a hybrid, has the problem always been there, or just after a long drive on the highway when the engine is working harder? A misfire can be caused by a bunch of things. When was the last time you had your fuel pump checked? Also, how's the throttle response when the engine is cold versus when it's warmed up?

The problem seems to be more noticeable after the engine warms up, especially when I'm trying to pass someone on the highway. I haven't had the fuel pump checked recently. You think it could be the fuel pump even though it's only really acting up when the engine's hot? And could this be related to the injection valve/injector? What do you mean by throttle response?

Okay, the fact that it's worse when warm points away from some sensor issues and more towards a component failing under heat stress. The fuel pump could be weak, struggling to deliver enough fuel when the engine demands it most, but the injection valve/injector is the more likely culprit. Think of it like a clogged artery - not enough fuel getting through to create a proper combustion. Throttle response is how quickly the engine reacts when you press the accelerator. If it's sluggish or hesitant, that's a sign something's not right in the fuel delivery or combustion process. I would recommend taking it to a trusted mechanic or the dealer. They will probably replace the injection valve/injector.

I took it to my local mechanic, and they confirmed it was a defective fuel injector. They replaced it, and now it runs like a champ again. The final bill was 515€, including labor. Appreciate the advice!