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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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Related Questions

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.

What happens if you dont fix catalytic converter?

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

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.

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.

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.

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.

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!

Where is o2sensor?

Somewhere in the exhaust system, and sometimes there are more than one. In a Mazda MPV you should have one in each exhaust manifold and another one downstream from the catalytic converter. (It could be worse: on a Porsche Boxster there's one per cylinder.)

95 z28 won't go more then 35mph. Won't rev above 3000rpm and running temp is ok WHAT IS WRONG?

I had this exact same problem with my 94Z28 and it needed a new catalytic converter. The current one was clogged. The MAF(Mass Air Flow) sensor might be bad to check it unplug it with the car on maybe drive down the street or something if it runs the same its bad if it runs worse then get the catalytic converter checked as the first response said

Can you remove the catalytic converter on your 2001 Ford Focus with 2.0 dohc No smog check in your area Want to increase fuel milage?

It is not legal, and as the computer tries to correct for the missing converter, the fuel economy and engine performance will suffer. Most likely if you remove the cat, the fuel mileage will get worse. Ok, so since that won't work, can I buy a turbo muffler or something, such as Hooker. You can convert it to a true dual exhaust system and it will help your fuel economy but it is not cost effective. By the time you purchase the necessary parts and another converter to keep it legal, the money you spend can never be recovered in fuel savings.

What caused the speed to drop although i pressed the accelerator. My car W 210 E 200?

If the check engine light illuminated start with having the codes read. Could be as simple as a dirty fuel filter or worse, a damaged catalytic converter.

Will a hole in a muffler affect gas mileage?

It can, and usually it will make it worse.

Does an exhaust manifold get worse if it does not get replaced?

If there is existing problems yes it can and most likely will become worse!

How is the gas mileage on a 90 Camaro rs V8 Is it much worse than a V6?

A v-8 will always get worse mileage than a v-6. If you're worried about gas mileage, don't be driving a Camaro. i have a 92 rs and a 90 rs. i get about 25 mpg

What the symptoms of a bad catalytic converter?

The main symptom is a complete lack of power. By lack of power i mean holding the gas pedal to the floor and only going 15 miles per hour. The car will idle well but no power hardly at all. Another symptom is rattling. If you strike the bottom of the Catalytic Converter wil a rubber hammer you will hear rattling from inside the converter. That indicates that the honeycomb matrix inside the coverter has broken apart. Finally, if you ignore the loss of power (it gets progressivly worse) eventually the car will not even start. Please keep in mind that the converter does not instantly go from good to plugged. It takes time. Mostly you notice the power loss on top speed first.For example only being able to go 50 m.p.h. . Then later on only 40...Again, the power loss gradually gets worse. If you really think the converter is plugged then you can disconnect the exhaust in front of the converter and see if the power returns. Also please keep in mind that some cars have "pre-cats" or "mini-oxidation" converters. Thay are a small catalytic Converter in front of the main converter. They go bad as well. Matter of fact, the last car i had with a bad "cat" it was one of those pre-cats. It was on a Toyota. One last thing...Mercedes Benz has a recall on the Converters on some models. You can get it replaced fo free. (normally $800) About a year ago i had a Mercedes come in with a top speed of 5 MPH. I removed the cat and the guts of the converter poured out like coffee grounds. Free replacement from the dealer Some cars have up to 4 cats so keep that in mind also. best of luck ^_^

What would happen if you take the catalytic converter off your 95 chev 350 truck?

Nothing would happen badly, worse case is the check engine light MIGHT come on due to the oxygen sensor being moved. but besides that it gives a great sound, and power to your car

What is the typical gas mileage of a hummer versus the average car?

The gas mileage of a Hummer is worse than any other civilian vehicle, as it is around 9 MPG (miles per gallon). The average American gas millage is approximately 20 MPG, so the Hummer's gas mileage is more than twice as worse than an average car's gas mileage.

Why is your gas mileage worse in the winter?

dense cold air requires more fuel

How do you know if a catalytic converter is getting plugged?

1) Take it off and do a visual inspection 2) loss of power 3) glows red when vehicle driven - easily seen at night 4) Blue color when cold 5) internal rattle - worse when cold The above are common symptoms

Do you get better gas mileage when you fill up your tank?

no if anything it is worse because of the added weight