Mazda 6 Service Manual: No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

No.19 excessive shift shock on torque converter clutch (tcc)

No.21 noise occurs at idle when vehicle is stopped in d, s, l ranges, or in r position

Other materials:

Mazda 6 Service Manual: Recommendations for Shifting
Upshifting For normal acceleration, Mazda recommends these shift points: For cruising, Mazda recommends these shift points: Downshifting When you must slow down in heavy traffic or on a steep upgrade, downshift before the engine starts to overwork. This reduces the chance of stalling and ...

Mazda 6 Service Manual: Nonreturn valve inspection
1. Remove the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION.) 2. Siphon the fuel from the fuel tank. Note Nonreturn valve is integrated in the fuel tank. The nonreturn valve is normally closed by the spring force. 3. Verify that the nonreturn valve is closed. If the nonretu ...