C70 diesel hissing and power loss

Hi, I have a 2009 Volvo C70 diesel with 95781 km on the clock. Recently, I've noticed reduced engine power, rough running, and a jerking sensation when accelerating. There's also a loud hissing sound when I put my foot down and fuel consumption is up. Suspect it might be related to the air intake, maybe the manifold flap control?

4 comment(s)

Sounds familiar. I had a similar issue with my C70, though I can't say for certain if it's the same. Was the hissing sound very noticeable? And did it feel like the engine was misfiring, especially at lower RPMs?

Yes, the hissing is quite loud under acceleration, and the engine does feel like it's misfiring, particularly when pulling away. Did you ever figure out what was causing it?

Yep, sounds like the same thing. In my case, it turned out to be a defective intake manifold flap control. I tried a few things myself, but ended up taking it to a workshop. They confirmed the diagnosis and replaced the unit. Best to get it checked out professionally.

Thanks for the advice. I'll book it into a workshop. Turns out you were spot on. The intake manifold flap control was faulty. Repair cost me 465€, but the car is running perfectly again.

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