Peugeot Partner Whistling Noise and Power Loss

I had a similar problem with my Partner. The symptoms you describe, especially the whistling and loss of power, sound familiar. Have you checked the intercooler pipes for any leaks? It could also be related to turbo lag. It's like trying to run a marathon with a backpack full of bricks – the engine just can't breathe properly.

Thanks for the quick response! I haven't checked the intercooler pipes specifically. How would I go about checking them for leaks? And could turbo lag really cause the engine to stall at idle? I thought that was more of a performance issue at higher speeds.

Checking the intercooler pipes involves visually inspecting them for cracks or splits. You can also try feeling around the joints while the engine is running (carefully!) to see if you can feel any air escaping. As for the stalling, severe turbo lag can contribute if the engine management system isn't compensating properly. It's like trying to balance a spinning top - if the spin isn't consistent, it'll fall over. However, given the whistling noise and other symptoms, I'd strongly suspect a defect in the wastegate valve. The hissing under acceleration is a telltale sign of escaping boost. I would suggest visiting a workshop.

Thanks a lot for the detailed explanation! I understand much better now. I'll take your advice and get it checked at a workshop. It turned out to be a faulty wastegate valve, and the repair cost me 860€. Hopefully, this will fix all the problems.