Some 2009 Mazda Tribute gasoline-powered 2.5L engines built from Oct. 27, 2008, and Nov. 28, 2008, may exhibit a high-pitched metallic whistle/whine noise during cold starts.
The noise is likely caused by the smooth idler pulley in the serpentine belt drive system. The noise will be most noticeable between 1,100-1,500 rpm and may be more noticeable during engine deceleration from 1,500 rpm.
Verify by removing the accessory drive belt (the noise should disappear).
Replace the smooth idler pulley assembly with P/N ZZC2-15-940.