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Catalytic Converters
Fuel Economy and Mileage
Pollution

Why would a car get worse gas mileage after the catalytic converter was replaced?


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2011-09-13 17:15:38
2011-09-13 17:15:38

why does a larger diameter exhaust increase power? lower bac-pressure. A reduction in flow resistance to exhaust gasses leaving the engine is a net increase in flow potential, hence more power. It requires less fuel to do the same work. Now consider putting something in the exhaust system that increases flow resistance substantially, like a ceramic honeycomb element in a catalytic that was not there before. Lost flow potential, increased fuel consumption to produce same engine RPM's. Also, was the o@ sensor checked? is the emissions system completely functional? Do you know for a fact it is? Are you absolutely sure? Because if they engine is running cooler than design temps, richer than optimal fuel mixture, or without Exhaust Gas Recirculation, it will produce excessive soot in the exhaust. Black smoke at muffler? This soot will rapidly clog the hoeycomb channels, and further restrict the exhaust. The soot bakes into clay at exhaust temps, clogging it up until you are back where you started, punching out the ceramic internals to recover flow potential so the car will run. Emissions system components are covered under federally mandated warranties in compliance with the clean air act of 1985. Some of which may be active for your vehicle. Looking into that may find you getting these things fixed by the dealership at their cost. That worth a look?

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Modern cars use two oxygen sensors to monitor the exhaust before and after the catalytic converter. Removing the catalytic converter would cause your engine to run improperly, possibly causing damage and most likely making your gas mileage worse. Just replace it if it's broken.

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When you get an odor of rotten eggs coming from your exhaust it means that your Catalytic Converter is pooched. You must replace it. Call around to get the best price. The Catalytic Converter is a part of your exhaust system. Your exhaust system must be free flowing in order for your car to run well. If your car is sputtering and gets poor gas mileage it is because your Catalytic Converter is plugged up and needs to be replaced. Your car will most likely run much better afterwards. Good Luck! Jim.

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You will fail an emission test and worse case, the engine will fail to run if the cat gets plugged up.

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Check for fuel leaks and proper fuel pressure.

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Yes, normally it makes it worse. On a fuel injected car the computer will try to adjust the fuel and timing to get the after cat O2 sensor to start working, this will cause performance and economy issues plus a check engine light. It is also highly illegal to remove a cat and not replace it.


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