Has anybody removed the cat off a 5.4L. If so did the check engine light coming on?. Also do you think there is any way the dealer could notice if the cat was gutted out?

 

Nobody? Thats hard to believe.

 

Todays cats don't cause a whole lot of restriction. Why would you want to remove it? Or gut it out?

I haven't looked but is there any sensors behind it or on it? If so, then I'm sure you'll throw a light if you remove those too.

 

I'd be less worried about the dealer finding out and more concerned with any kind of emissions law enforcement. I believe it is Federal violation to tamper with the catalytic converter.

 

i do not know a whole lot about this, but. the catalytic converter produces a certain amount of heat and back pressure. with out this heat and back pressure the sensors will not pick up the correct readings and you will lose torque because of the lack of back pressure. and your sensor will burn the fuel ineffeciantly because there isnt enough heat for the sensor to pick up. anyhow that is what i have heard. also there is no sensor after the convertor.


-nathan

 

I've had my cat off once for a week and noticed no gains anywhere. The only thing I got was loud noise! I but it back on and have been happy ever since. A stock Ford cat runs about $1200 so the last thing I'd be doing is punching it out.

 

I would leave the factory cat alone and save it due to its cost and buy a Random high flow replacement cat for about 1/3 the money. Do they help????? don't know.

 

Not a good idea. You are at an OBDII calibration. You have upstream and downstream HEGO sensors. You will run open loop due to the fault codes, and then trip the MIL. Your engine is calibrated to run with the cats, which are low cell brick density units (i.e. low estriction).
Keep the emissions stuff on, OBDII is a different animal than non-OBD.

 

So removing the cat or replacing it with a "high flow" will do basically zip? Is the Superduty exhaust that good of a setup from the factory? I put in a Gibson Sweptside SS on my rig yesterday. It's growing on me but my immediate impression was disappointing. It seems to perform better with a good half ton or so in the bed.
Now if the cat-back didn't yield the results I expected and neither will a cat mod, then what about the Y-pipe? Is there a considerable benefit in enlarging those pipes?
It seems to be that unless you have some sort of forced induction, then a more free-flowing exhaust is just not needed. The bottom line looks like the only real advantage to changing the exhaust on a stock motor is for sound. The Gibson I chose actually hits the mark with what I want on a work truck. I'd just like to see a little more performance.
Anybody have some more input?

 

I got a noticeable improvement from the Banks "stinger" (cat-back) system when I had just that part installed. Then, with the installation of the headers and new "Y", the performance increased again. You might try resetting the computer to see if it helps. I like to do that every time I install a new "performance" part.

 

when i had my muffler and tailpipe off i noticed that my truck turned the rpm up faster and easier. but, i felt like i lost some torque. she just didnt hold the hills on her own like before without downshifting. i really liked the sound with the exception of how much it cackled. just to much fer me.


-nathan

 

Exhaust and intake losses are 5% nominal. There is restriction throughout the entire system. A cat back may help free up some of the losses, but more is lost on bends and yes, the cats. You will not regain much power. Pick the system that you like the best sound with.

 

I am not concerned with power only sound. However after reading all the replies I think I will wait until the cat is clogged up before I gut it out. Thanks for all the input.

 

BTW, warmdye, I think you've got a typo:

2001 F250 5.8L 4X4 -
3 Chamber Flowmaster, K&N Air Filter

It should be 5.4, not 5.8.
Also, how do you like the sound of your flowmaster?

 

[updated:LAST EDITED ON 23-Apr-02 AT 10:27 PM (EST)]Your right. Thanks
Your truck looks exactly like mine.