Some 2001-2009 Mazda B4000 vehicles may exhibit a buzzing noise from the upper engine area at about 1,900 rpm under light load acceleration.
1. Verify the concern.
2. Prior to following normal diagnostics, check the fasteners that attach the ignition coil bracket to the intake manifold for proper torque.
a. If the bolts are found torqued to 89 in.-lbs., proceed to Step 3.
b. If the bolts are found to be torqued correctly, this bulletin does not apply. Follow normal diagnostics.
3. Torque both ignition coil bracket bolts to 89 in.-lbs., followed by an additional 45 degrees of rotation (torque-plus-angle).
4. Verify that the buzz noise has been eliminated.