hi people,

really need some good sound expert advise here, a month ago i was driving my 2008 mk2 focus 1.8 zetec petrol duratec, when all of a sudden i heard a strange noise coming from the engine bay that was like a mid pitch humming that runs intime with rev increase, managed to limp the car home but when i pulled up outside my house the message came up engine system problem and the car just lost all power.  checked again in day light and battery was fried so put a new one on and car now starts fine but noise still there, after looking at the engine noticed that the coil packs were fried with oil so changed the seal and replaced all plugs and 4 new coil plugs, the power is back, it will rev up to 4 - 5000 revs and speed is fine but the MPG is no at 11.2 and the noise wont go away. also changed drive belt tensioner and belt but it wont sit quiet. before throwing £££ at a ford garage any advice please, have had a code reader on there and the code only flashes up for a second and then goes away?????

UPDATE... ecu reset has got the mpg back to 28, its just the annoying noise now, would a split air hose do it?