i have a 1.8 52 plate coupe.
Staurday night i heard a strange noise like there was a hellicopter going over but it was comming from the car. It seemed to stop when i turned the aircon off. But today i heard it again with the aircon off but only when the engine was on the overrun. It feels slightly sluggish in the low revs and used abit of oil in the last couple of weeks which it doesnt usually do.
i cleaned the throttle body and checked the exhaust but i cant hear any leaks and it wont make the noise when reving on the spot.