Hey there,

My XC90 just had one ignition coil replaced as it was causing a misfire on the fifth cylinder. For a week after it ran very well but now it has developed a hissing noise when I get up to over 60km/h. The hiss sound is also prominent when I let off the gas (especially at this point). Today.. the car ran very rough at one point followed by a louder hiss. now it is running better (still doesn't feel quite right though) and the hiss is still very loud. Any ideas? Is something just disconnected or out of place because I have no codes, messages, or warning lights. All replies welcome!!