Avensis Turbo Issues

Sounds rough! I had similar problems with my old Renault Megane, though it was a diesel. The symptoms you're describing make me think you might have a boost leak somewhere in the turbo system. Have you checked for any obvious cracks or loose connections in the hoses around the turbo?

Boost leak, huh? I'm not really a mechanic. What exactly is a boost leak, and where should I even start looking for these hoses?

A boost leak is basically when the pressurized air from the turbocharger escapes before it gets to the engine, leading to lower power. On my Megane, the issue ended up being a faulty electrical bypass valve also called boost pressure actuator controlling the turbo wastegate. It might be worth getting it checked by a professional, since a defective boost pressure actuator is a common problem in turbo systems. It can be tricky to diagnose without the right tools.

Thanks a lot for the help! I took it to a local garage, and they ran some tests. Turns out it was the boost pressure actuator. They said the electrical bypass valve was defective. Cost me around 250€ to get it fixed, but now it's running like new again!