Sprinter Diesel Losing Power Hissing Sound

Sounds like a pain Reduced engine power and hissing definitely points towards an air intake issue I had a similar problem with my old Vauxhall Astra a few years back, different engine, but same symptoms Jerky acceleration and the hissing noise are classic signs of a problem with airflow control The intake manifold is basically the part of your engine that distributes the air coming in If the 'flaps' inside aren't working right, it messes with the air-fuel mixture, impacting engine performance and sometimes even causing engine misfire What mileage are you getting now compared to what you used to get

Thank you for your swift and informative response It's reassuring to know someone else has experienced a similar issue Regarding fuel consumption, I haven't done a precise calculation, but I'd estimate I'm getting at least 20% fewer kilometers per liter than I was previously When you say 'flaps', are these things that can be cleaned or adjusted, or is it more likely to require a replacement

Okay, 20% is a significant jump in fuel consumption, so yeah, something's definitely up Regarding those 'flaps', they're part of the intake manifold They control the airflow into the engine Sometimes they get gunked up, but often the problem is the control unit itself, the little motor that moves them It might be worth getting a diagnostic check done It will point directly to the faulty part Unfortunately, it sounds like a workshop job Replacing an intake manifold can be tricky, and you'll need to reset the engine management system afterwards If it's just the control unit, that might be cheaper, but honestly, with those symptoms, prepare for the worst I'd get a quote from a mechanic

I wanted to express my sincere gratitude for your invaluable advice and support After a trip to the workshop, it turned out that the intake manifold flap control was indeed defective, as suspected The total repair cost came to 465€, which was a bit of a blow, but significantly less than a whole new engine The van is now running smoothly again, and the dreadful hissing noise has vanished Thank you once again for your assistance