The manufacturer says that the probable cause for this engine noise is due to the cylinder head being unevenly torqued.
To correct this problem, Acura recommends that you retorque the cylinder head as follows.
1. Allow the engine coolant temperature to drop below 100° F (38° C).
2. Remove the camshafts.
3. Using the loosening sequence (Figure 1, reversed), individually loosen then retorque each cylinder head bolt to 7 ft.lbs.
4. When ALL head bolts have a torque of 7 ft.lbs., retorque, using the torque sequence shown in Figure 1 to 22 ft.lbs., then to 43 and finally to 61 ft.lbs.
5. Reinstall the camshafts and adjust the valve clearance to 0.15 mrn INTAKE and 0.17 mm EXHAUST.
Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.