When the car engine pinging occurs on a high altitude roads such as driving on a mountain area.
Car problem Diagnosis
When a car engine is pinging this indicates that there is a pre-ignition inside your car combustion chamber, pre-ignition happens when the fuel ignites before the pistons reach the top of the combustion chamber and this occurrence will results to pinging sounds you heard from the car engine. When the pinging sounds occur while driving on a high altitude areas such as 7,000 feet above sea level then the reason of engine pinging is probably a thin air, as you can see the air at high altitude areas is already thin and thin air will tend to cause an early ignition of the fuel inside the engine combustion chamber.
Possible Cause of Engine Pinging Sound at High Altitude
Engine pinging sound is cause by a thin air
All about car Recommendation
How to Fix Pinging Sound on Engine
To eliminate the engine pinging sound when you are about to drive on a high altitude areas use a high octane gasoline, high octane gasoline has more resistant to pre-ignition because it burns slower than a low octane gasoline.
If there is no pre-ignition occurrence inside the engine combustion chamber therefore no pinging sound can be heard. To determine the octane rating of the gasoline you use just look at the label displayed on the front of the gas pump. High octane gasoline have an octane rating of 92 and above so it will easily be check if you try to use one.