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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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โˆ™ 2011-09-13 17:15:38
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Q: Why would a car get worse gas mileage after the catalytic converter was replaced?
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How do you bypass the Cadillac converter on a 1999 Grand AM?

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.

Your 88 corolla fx idles roughsometimes worse than others Sputters off idle sometimes has an oder at the tailpipe like rotten eggs Always poor mpg Whats upyou removed vacuum to the egr no help?

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.

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

Check for fuel leaks and proper fuel pressure.

Does cutting off the catalytic converter affect gas mileage?

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.

How removing the catalytic converter affect the oxygen sensor?

With any vehicle modern enough to have a catalytic converter and oxygen sensor, removing either or modifying the emissions control system in any way is not advisable. Because the components of the system are so interrelated, chances are very high that you will force the system into "limp home mode" since it is not getting proper information from a sensor. The car will keep running and you may notice no difference in driveability but you will likely experience worse gas mileage and possibly shortened engine life. Keeping it stock is the only smart ( and legal ) thing to do.

My Toyota Previa as a wineing noise when you accelerate and is getting worse?

Previas have a history of a whining noise coming from the catalytic converter. There is a bracket inside the converter that when loose or has came apart creates the whining noise during acceleration. It especially is very pronouced during high speeds in the freeway. You might be in for an expensive cat converter replacement.

What happens to mileage if exhaust had fully opened?


Will disconnecting the oxygen sensors improve your gas mileage?

God no. It'll make it worse! Oxygen sensors are what constantly tell your ECU the air fuel ratio. If you disconnect the sensors it'll make your car run bad with a mixture being either too rich or too lean. That'll mess up your catalytic converter too which can be an extremely costly repair. LEAVE THEM PLUGGED IN!

How does rear axle ratio affect gas mileage?

the lower your rear axle ratio, the worse your mileage.

1990 accord ex. i have oil in my airintake. replaced pcv valve it didnt help. whats wrong with my car?

A long shot: If your catalytic converter is failing, there can be a blockage in your exhaust that then increases blow-by past your rings in the engine, resulting in pressure building in your crankcase that forces oil (actually air saturated with oil) past your PCV valve. Had this happen years ago, and had oil in the air cleaner chamber of a Suzuki Samurai. Catalytic converter got worse, pressure increased to the point it would actually blow off the PCV hoses. Also had intermittent loss of power in the engine. Basically the guts of the catalytic converter were bouncing around and occasionally blocking the exit, causing the backup. Unfortunately the shop I took the car to for a diagnosis mis-diagnosed the situation and said I needed a new engine...I put in a new engine and still had the trouble! How to tell if maybe the catalytic converter is going bad? Hit it witl a mallet. If the element inside is loose you will hear it rattle around. Good luck!

Will removing the catalytic converter off your truck help with the gas mileage of a 2006 chevy crew cab with 4.8l v-8?

No. It can actually make it worse. The computer will try to adjust the fuel ratio to make the oxygen sensors read correctly. With no cat that is not possible.No. It can actually make it worse. The computer will try to adjust the fuel ratio to make the oxygen sensors read correctly. With no cat that is not possible.

Will a hole in a muffler affect gas mileage?

It can, and usually it will make it worse.

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