Car Start but Engine Initially Backfire

The car starts but initially backfires after starting. When a car backfires shortly after starting and usually occurs on the wet condition, then this is a sign of the problem of moisture inside the distributor cap. Moisture is the results of condensation from the air humidity, and interferes with the ignition system thereby causing the engine backfires shortly after starting.
However, if the car problem occurs even when the condition is not wet then this could be a problem of fuel injection system or one of the electronic sensors is faulty.
Possible cause of engine backfire at initial startMoisture on distributor cap or faulty sensors
How to fix engine backfire at startingFor moisture on the distributor cap, there is nothing much to do. Just avoid parking your car on open space especially if you anticipate rain. As for the faulty fuel injection system, bring the car to a reputable car shop and ask the mechanic to check the fuel injection.
If the mechanic told you to replace fuel injection, do not agree unless you seek a second opinion, usually, this kind of problem is blame to sensors that are not working properly.