hanseis1
C70 diesel hissing and power loss
Summary of the thread
A 2009 Volvo C70 diesel exhibited reduced engine power, rough running, jerking during acceleration, increased fuel consumption, and a loud hissing sound. These symptoms suggested a potential issue with the air intake system, specifically the intake manifold flap control. A similar case confirmed that a defective intake manifold flap control was the cause, and professional diagnosis and replacement resolved the problem, restoring the car's performance.
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4 comment(s)
hanseis1 (community.author)
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?
alinahoffmann9
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.
hanseis1 (community.author)
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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VOLVO
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C70
alinahoffmann9
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?