Peugeot 207 Intake Manifold Flap Issue

I have a 207, and your symptoms sound awfully familiar to what I went through last year. Reduced power, rough running, jerking... yep, sounds like intake issues. That hissing sound is a classic sign of a leak in the intake system somewhere. I would take a look at the intake manifold itself and all the hoses connected to it. The manifold flap is also a likely suspect. I have seen similar issues when there are misfires because the air intake is not working correctly.

What exactly was the issue with your car's intake manifold flap? Was it a simple fix, or did it require replacing the entire manifold? Did you also experience increased fuel consumption? How much did it cost to fix?

In my case, it turned out the intake manifold flap control switch was defective. This caused the flap to not open and close properly, messing with the air-fuel mixture and leading to the problems you and I both experienced. I didn't attempt a fix myself. My local garage diagnosed it pretty quickly and replaced the switch. I would recommend getting yours checked by a professional, it sounds like you have the exact same problem. My repair bill was around 465€.

I've booked it in with my local mechanic, and I'll mention the intake manifold flap control switch. Fingers crossed it's the same issue and the fix is straightforward. The mechanic confirmed that the intake manifold flap control switch was indeed defective. Replacing it resolved all the issues.