Odd engine noise at start up

[joe427]

Could be normal or maybe not.Really been the same since day one.
Odd louder engine noise at start up but the bit louder sound goes away after 30 seconds or so to normal engine noise.
I know it may be a cold start idle but it just sounds a bit weird.

 

[paris1]

From page 4-4 of the 2015 CX-5 owners' manual:
After starting a cold engine, the engine
speed increases and a whining sound from
the engine compartment can be heard.
This is for improved exhaust gas
purification and does not indicate defect of
the parts.This is why they put the book in the glove box.

 

[joe427]

Thanks.
I thought it may be from direct injection.
My '13 Lexus GS350 has some ticking noise when starting due to DI.

 

[CC58]

On cold start, valve timing is such that unburned gas is released into the exhaust manifold where it ignites causing rapid warm up of exhaust manifold and catalytic converter. Mazda is the first production car to have full length headers (kinda in a knot) and pass emissions because of this cutting edge engineering. The full length header makes it possible to run 13:1 compression on 87 octane gas which increases power by 15% and mpg by 15%.

 

[joe427]

On cold start, valve timing is such that unburned gas is released into the exhaust manifold where it ignites causing rapid warm up of exhaust manifold and catalytic converter. Mazda is the first production car to have full length headers (kinda in a knot) and pass emissions because of this cutting edge engineering. The full length header makes it possible to run 13:1 compression on 87 octane gas which increases power by 15% and mpg by 15%.

Very interesting.Thanks!(2thumbs)