Modus Intake Manifold Flap Defect

Sounds familiar. I've got a Renault Grand Modus, though not sure what year model. Had similar symptoms – the hissing was a big clue. Check your intake system thoroughly for leaks – could be splits in the hoses. An engine misfire might result from this

Cheers for the reply. When you say 'similar symptoms', did you experience the exact same set? I mean, the hissing, jerking and the fuel consumption increase? Trying to rule out other possibilities before I start ripping things apart.

Yeah, pretty much all of it. The rough running was intermittent at first, then got progressively worse. The hissing got louder too, and mpg definitely took a hit. I'd say get it on a diagnostic machine, but honestly, with those symptoms pointing towards air intake system troubles, and intake manifold flaps, you may need to get the mechanic involved.

Workshop confirmed intake manifold flap control defective. Quoted 465€ incl parts and labor. Booked it in. Thanks for confirming my suspicions!