Fortuner engine knocking sound

That sounds eerily familiar. I had a similar issue with my old Opel Insignia, although it was a diesel. Same symptoms, the knocking, power loss, even the smoke. Did you by any chance check the cylinder heads? Have you considered that deposits in the combustion chamber may be the cause of this knocking?

Cylinder heads are fine, I think. Deposits in the combustion chamber... interesting. How would I even go about checking for that, and what would cause them in the first place? I'm trying to avoid a costly repair if possible, but this knocking is making me nervous. Is that what you experienced?

Yes, those were my exact symptoms and that was indeed the cause. I'm no mechanic, but from my experience, I'd say take it to a workshop and have them scoped. If it is deposits, they can advise on the best course of action. It's better to be safe than sorry when it comes to engine knock – you really don't want to risk further damage.

Thanks for the advice! I took it to the workshop as you suggested. Turns out you were spot on – carbon deposits in the combustion chamber. They cleaned it all out, and the knocking is gone! Cost me 425€, which is better than a new engine, I guess. Appreciate the help!