Engine Noise

[smo]

At idle my 1.0L GLS 1999 Yaris seems very noisey. Cold start is fine however, as soon as it's up to temp it becomes unstable at idle. There is a high pitched hissing noise at idle which goes when you apply sum throttle.Also when going up a gear I tend to get the noise from the engine you would get if you were in a to high gear for that speed. Could it possibly be an air leak?

Any comments would be greatly appreciated

Thanks

smo

[Black Knight]

Does sound like an air leak somewhere. First thing I'd do is check the hoses going into the intake manifold for splits