I have a 2004 F150 5.4L FX4. I am getting a exhaust for my truck and would like to remove the cats. I have been told by a couple of people that if I did that the engine would not like it and would either not run right or would get a check engine light. Does anyone know any way around removing them without any problems, by either getting a performance chip to fool the computer or anything else. Thanks for your help.

 

removing the cats is not a good idea. if your state does not have emissions yet, it will soon. why do you want to remove them?

 

I ran with no cats for about 2 months. Then I put hi-flows on. I would NEVER recommend running no cats on one of these trucks. My truck back-fired, and lost quite a bit of mid range and low end power. Go with a good set of HI-flows. Removing the cats is just got worth it. Although it may sound better, the noise of hearing your exhaust over your stereo sucks, and you will sacrafice quite a bit of mid-range power; your tranny will be doing a lot of shifting. Hope this helps.

 

I don't want to sound like a smartass or anything, but KickinBlue4x4, you have "no cats" in your description of your truck, but then you recommended not taking them out. Just wondered why the contradiction there?

BT

 

He said.

 

Forgot to change the sig.

 

I removed my cats and installed dual exhaust with 2 flowmaster 40's that are downpiped infront of the diff. Im using the Diablo Preditor programmer to act as the sensors are still there . It solves the check engine lite and fuel mixture concerns. I would probably just remove the ( Y ) pipe and do dual exhaust with High Flows and you'll notice nice towing increase with some better fuel consump on the highway. Now im deciding on Headman or Gibson, and from what im reading, gibson leaks alot

Good Luck


99' 4x2 /extra cab

Upgrades, /8in lift /Mickey 35's /4:56's/ 9.75 diff/ detroit air locker/ Airbags/ Viair Pump/ Grover Air Horn/ Flex-A-Lite fans/ Diablo Programer. ""Oh, did i mention the 450HP BBC Motor"" Just cause i own the truck, doesnt mean i have to like the motor !!!!!!!!!!!!!!

 

Did you keep the two front O2 sensors? You can go without the rear ones as they just check for cats (check engine light) but the front two take care of fuel mixture.

 

Norm, being from Ca., you must know someone down at the local inspection station! Thought Ca., was death on any mods that effect exhaust emisions?

 

You are right, he (vegasman) must know the inspector! How else would he get away with no cats in Cali. The only other way is if the truck is not used on the road, right?

 

Check with Casper Electronics at casperelectronics.com They have a wiring harness that can be plugged into the down stream cat wiring harness that will eliminate the engine light.

Cost run around $90.00 per harness.

Total elimination of back pressure or a drastic reduction other than what the computer is programmed for actually causes a breathing problem. Tuned exhaust headers rely on the pulse of the gases being pushed out by each piston to maintain the flow. A good example would be when someone raises the intake port in a 2 cycle racing motor to increase gas flow. If the port is changed drastically enough the engine will not run right until the exhaust header chamber size and shape are retuned for the pulse. Exhaust headers for your truck work under the same principle. Have you ever noticed the difference in the length in the header pipes? That's to govern the timing of when the pulse reaches the collector chamber in the header. Hold your hand near the end of the pipe of a Harley Davidson and you'll feel the pulse I'm talking about. Your motor has to synchronize 4 pulses on each side of the motor and it smooths out so it harder to notice them. The advice the other guys are giving you about putting low restriction cats is good. If you install dual exhausts from the exhaust manifold back you may want to consider a cross over pipe to equalize the pressure between the two sides. Its not really necessary but you will have fewer problems with burnt valves etc.

 

I have an '01 5.4 w/ about 124k and I am wondering how i will determine when its time to replace cats, mufflers, etc? Thanks,

 

Don't worry about replacing them until you start getting check engine lights with catalyst efficency codes.

 

is it weird the my truck has 2 cats?

 

Thanks for info Quintin! Does anyone have part number for pre-cat O2 sensors? I haven't removed them yet but I am tempted to replace them soon since I have about 124K. I have an '01 5.4. Can I find the correct parts at my local auto supply; like Autozone, Advance, O'Reillys? Thanks,