LandCruiser intake manifold flap issue

That sounds awfully familiar. I had something similar happen with my LandCruiser. Symptoms were almost identical – the hissing was a dead giveaway. Have you checked for any error codes? The intake system can be a pain; the manifold flap is a common culprit. Is the hissing constant, or only under load? That might give us a better idea of where to focus.

Thanks for the quick response. I haven't checked for codes yet, but I will. The hissing is definitely only when accelerating, especially under load. What was the eventual fix for your issue?

Right, hissing under load points even more to the intake manifold. In my case, it was indeed the intake manifold flap control. I initially hoped for a simple fix, but no luck. I'd suggest taking it to a reputable workshop; messing with the intake system without proper tools and knowledge can cause more harm than good. They should be able to diagnose it properly and give you a definitive answer. Prepare for a somewhat hefty bill, though; these things aren't cheap.

Appreciate the advice. I ran the codes and got a hit for the intake manifold flap. Took it to the workshop; they confirmed the switch was faulty. Cost me 465€ for the repair, but she's running smooth again. Thanks!