The car ran fine until recently it struggles to even get to 40mph. The car is noticeably lounder and sounds under streas when accelerating. I changed the spark splugs and the coil pack and it did nothing for my problem.
My car has an automatic transmission.
This may be a sign of a clogged catalytic converter. As you may already know, the catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly (think of a backed up sink). When this happens, the engine I forced to work much harder to expel these gases. This often results in the engine bogging down and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.
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