I have a 1999 F150 V6 and I was looking under it the other day and noticed that has 4 cats on it. WHAT GIVES? most of my friend with trucks have just one, so why would my v6 have 4. What are the laws on removing atleast 2 of the 4 that i have. can i do it?
Also a shop here in town said that they could take them off, hollow them out and put them back on would that make my truck alot louder, or what.

Thanks for your help,
JDm

 

I got 4 too but as far as I know the laws in the 2 states I live do not allow me to remove them. It pisses me off!

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'97 XLT Clearcoat Red 4x2
17 inch Wheels,Stepside, K&N,bedliner, 32 inch tires, flowmasters, deep tint, big Ford oval on back window, 5 spd, platinum plugs, CB, hidden hitch, ford emblem hitch cover and a little wal-mart smiley face on the antenna wearing a coboy hat :-)

http://www.my-f150.com/waldo0506

 

Removing the cats is illegal in every state; it is a 50 state federal law. It is even illegal to replace them prior to 50k/5yrs unless they are faulty. I'm not saying that people have not removed them. They do lower sound, but current cats flow much better than older designs.

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2000 F-150 XL, RC, LB, 5.4L, 4R70W, 3.55LS,
Class III tow, Payload #3, & Convenience pkgs.,
4-wheel disc/ABS, Chestnut/Parchment 40/60,
Ford bedliner w/Paintsaver & gas/wheel/spare locks,
K&N F.I.P.K. w/Outwears pre-filter, Superchip,
Dynomax ultra-flow welded 3" cat-back w/ 3" Y-pipe,
Hellwig front & rear anti-sway bars, Rancho RS 9000s,
Mobil 1, K&N oil filter.

 

My Truck just hit 50k miles last week so maybe i should look into some higherflowing cats. Since i have 4 cats now do you think that i could still pass with just 2 cats? what about hollowing out 2 of the 4 to give my truck a deeper rumble. Because if i just had the hollowed out and not cut off an inspector would never know that they were hollow.

What kind of difference do you think that i will hear sound wise with 2 cats hollowed out? would it be lower/higher in tone or just plain louder than before?

 

i would be careful about doing this if your oxygen sensors are behind these it will mess your comp up.....the air / fuel ratio will not read rite on your sensors and it will cause the computer to lean your motor out and you will lose bigtime power..just a suggestion hope everything works out allright
jimmy

 

You have two pre-heaters and two converters plus 4 oxygen sensors. If you modify these CATS and not calibrate the ECM to the new O2 sensor(s) readings, you will mess up the AIR/FUEL ratio and LEAN out the engine. Ask members of this board who have installed "true-duals" what happens to their low-end torque. I am not saying that the engine cannot be modified to take advantage of higher flowing CATS. What I am saying is, that under the OEM configuration from the factory, messing with the CATS will produce severe drivability problems.

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99 4X4 XLT S/C with ORP
5.4L 3.73LS
Flow Master Dual Exhaust
K&N Filter w/ Intake Mod
Flex-a-Lite Black Magic 150 Electric Cooling Fan
Jason "Hugger" Truck Lid

 

Is there anyway to rig the o2 cencors so the computer thinks the cats are still there?

 

Yea I need to know I really want to get rid of 2 cats on my truck, I have a V8 4.6l s/c truck. I have a flowmaster but I think its time to take off some of the cats.

Any one who has done this let us know what can be done!

 

 

I KNOW THAT I CUT OFF ALL MY CATALYTIC CONVERTERS AND IT WAS SO LOUD IT WAS ALMOST UNBEARABLE. I HAD FLOWMASTER DUMPED STRAIGHT DOWN WITH NO CATATLYTIC CONVERTERS. IT REALLY MADE A DIFFERENCE IN THE OVERALL PERFORMACE BUT I WOULDN'T ADVISE YOU DOING IT UNLESS YOU ENJOY SETTING OFF CAR ALARMS WHEN YOUR JUST IDOLING BESIDE THEM. IT'S TOO LOUD.

 

Is that why your yelling? j/k

 

mattbert,

LOL,


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2000 F150 XLT 4x4 Sport
5.4L ORP s/c
Power everything
Ravin Z33 3" SI/SO Performance exhaust
Tinted windows
Vent Visors
Bug Deflector
Ford Duraliner
Ford Racing Shoulder Pads
Pant savers
Airforce One FIPK
Ford Duraliner

Next: Superchip, pulleys, TB spacers, Electronic supercharger.
Maybe a lift kit if I can know enough about them

 

Wow, a lot of kooky info here.

The 2nd O2 sensor has nothing to do with your A/F ratio. All it does is detect if the CAT is there or not, that's it. All it needs is a different signal than the front O2. You can make a simulator, leave it in the open air, install a resistor or any number of things. They are very easy to fool. It's not some special Ford thing, it's just regular OBD-2.

The first O2 sensor should be in front of the first CAT. This is the one that the ECU uses to determine the AF ratio under closed loop operation. You can remove the exhaust completely after that, and the ECU won't give a crap so long as the two O2 sensors receive different signals.

-Jay
98 F150 4x4 SC ORP with all 4 cats in place

-Jay

 

where do i install the resistor