My 2004 Mitsubishi Pajero backfired on LPG and blew the air intake off and filter, and also damaged the catalytic converter and sent the computer into meltdown. The car is still not performing as it should with long shifts between second and third and between third and fourth. The idle is some times rough and hesitant. It has been back to gas converters and my mechanic, but with no improvement.
Backfiring is usually caused by a problem with the ignition system, and usually fixed by replacing the spark plug leads. It happens when the LPG/air mix in the intake manifold is ignited by a random spark, and it often results in the air intake and filter being blown away. It is unusual to damage the catalytic converter and have the computer meltdown, and damage to the auto trans is unheard of. Check the ignition system and certainly replace the spark plug leads, and have the auto checked by a specialist.
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