Honda City Engine Problems
Honda City 'pinging' under load
You don't say what fuel you have been running it on, but if you've been using regular unleaded try a higher octane rating fuel, such as 95 PULP or even higher 98 and see if the pinging goes away. You can have your car serviced by any qualified mechanic without affecting the warranty, as long as it is done according to Honda's recommendation.
Idle wild
YOU'VE run into one of the problems of buying an import without local support. You really need to find a Honda expert to help you with this one, and I would suggest you try Adam Kovarik of In-N-Out Motors. He did his time on Hondas and has an extensive knowledge of them. He can be reached on 9544 9986.