catalytic convertors

[justin's_94]

I have a 94 xlt with a flowmaster series muffler on it, I want to cut off my catalytic convertors and put a straight pipe on instead. I live in good ol' South Carolina so we don't have any smog checks or any garbage like that. I just want to know if there are any sensors in there that I need to be aware about. Also when I looked underneath there, it looks like that are two cat convertors. Is one a cat and the other a resonator or what?

 

[JoeC5]

Cats are there for a reason. The only thing you will do if you take them off is pollute are air . Just put on some high flow cats.

 

[mrboyle]

In addition to polluting the air, removing your cats will actually hurt the performance of your X. The engine management system (the computer) needs the back pressure created by the cataletic convertor in order to function properly. Besides the cats DON'T restrict the exhaust system (unless they are bad) any more than the stock muffler did. If you still feel you need to remove the cats, take Joe's advice and have them replaced with a single high flow unit. This will help (slightly) and won't disrupt the ECM's function.

 

[jimbo74]

yeah dont do it...the cats are there for a reason...it is actually a federal offense to take them off if they arent broken..... it will also hurt performance and wont make it much louder.... the stock cats are already hi flow units.....

 

[drew22]

high flow cat

Where can I get a high flow cat for my explorer?

 

[LukeDog3D]

Cutting out the cats does not hurt performance or engine operation as long as the oxygen sensors are located upstream of the pipe you are replacing.

 

[JoeC5]

Hey Drew, you can get a high flow cat from www.truckperformance.com

 

[mrboyle]

LukeDog3d
YES, removing the cats WILL HURT PERFORMANCE! I have seen it happen to several vehicles. It interfears with the opperation of the EGR system as well as creating false signals from the O2 sensor. The auto manufacturers have spent millions of dollars researching and developing the engine management systems it today's automobiles and EVERY part is taken into consideration.

 

[JoeC5]

Hey Lukedog, I would have to agree with MrBoyle. Also I'm pretty sure he knows what he is talking about being a certified master tech and all.

 

[LukeDog3D]

Not to disagree with a knowledgable fellow such as yourself, but mine seems to be running fine these days...

If the sensors are located upstream of the C/C, how can they possibly analyze if spent exhaust has passed through the converter or through a void space? The computer responds to the change in backpressure the same way it does when you install a performance exhaust. Now if the sensors are located DOWNSTREAM of the converter...thats a different story.

 

[S.Matsushige]

The sensor on '91 and '92 seem to be before the cat, but I don't think removing it is the answer. Case in point would be that I have a friend who has a '91 as well and against my advise, he gutted his cat. I replace mine with a high flow. Now I know there are a lot of variables between his and mine like me having a modified air box, different muffler and headers, but I seem to have a smoother running engine, better mileage and seem to have more power. I think backpressure my be critical in the operation of the 4.0. I would say just going with a quality catback system should do wonders. I know we all love our trucks, but wouldn't it be ashame if they made them illegal because of the pollutants. Take it for what is worth.