Q: Backfires on start up

Backfiring can be caused by a number of faults. If the ignition timing is incorrect either by the distributor being out of alignment or a jumped timing chain, backfires can occur. Also, if ignition wires are crossed / incorrect firing order, backfires can occur. Also, too much or too little fuel due to faulty fuel injectors or incorrect fuel mixture can cause a backfiring condition as can faulty spark plugs. Other mechanical issues such as burned exhaust valves in one or more cylinders can cause backfiring.

Since any of multiple components can be the cause, have a certified technician look into the backfiring to isolate the exact cause.