Questions about CAT Delete
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Questions about CAT Delete
I am thinking about removing my cats on my 98 f150 with the 4.6 .. after doing a bunch of research, i still havent found a solid answer so ive decided just to ask in a new forum.. my truck has the 4 Cats and im not sure if i should cut off all 4 or just the 2 larger ones.. Also i am not sure how removing the cats will affect my performance and mpg.. and what should i do with the O2 sensors once i remove the cats.. i have never done this before so any advice or help would be appreciated. thanks
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Originally Posted by robert150lee
I want to do this as well! I just want to removed the front 2, i believe they are (precats) well so ive heard. one has a rust hole in it and is loud and i would rather just put a piece of pipe in place of it.
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From: Missouri
If you remove all 4 you must tune to delete the secondary sensors. You should however be able to remove the 2 rear cats without any tuning.
Either way, your MPG and performance will not be changed in any way.
Either way, your MPG and performance will not be changed in any way.
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From: missing Texas...
the fronts can be removed without repercussion, while the rears cannot
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Originally Posted by tarajerame
Quote:
Originally Posted by avfrog
If you remove all 4 you must tune to delete the secondary sensors. You should however be able to remove the 2 rear cats without any tuning.
Either way, your MPG and performance will not be changed in any way.
it's actually the other way around...
the fronts can be removed without repercussion, while the rears cannot
Originally Posted by avfrog
If you remove all 4 you must tune to delete the secondary sensors. You should however be able to remove the 2 rear cats without any tuning.
Either way, your MPG and performance will not be changed in any way.
it's actually the other way around...
the fronts can be removed without repercussion, while the rears cannot
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From: missing Texas...
the smaller cat, is the one you can remove without issue, as it's actually a "pre-cat"
it's the ones on the right side of the exhaust system in this picture
it's the ones on the right side of the exhaust system in this picture
Last edited by stoffer; Jun 2, 2013 at 09:17 PM.
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I actually left my precats (the small ones in the bend) in and removed my actual cats and replaced them with just straight exhaust piping. I have had no problems with sensors. It didn't show any gains in HP or MPG, but it did give my truck a VERY nice exhaust tone and volume change....
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will removing both pre cats set off any codes? and will most exhaust shops cut them out?
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Originally Posted by tarajerame
the smaller cat, is the one you can remove without issue, as it's actually a "pre-cat"
it's the ones on the right side of the exhaust system in this picture
IMAGE#1
it's the ones on the right side of the exhaust system in this picture
IMAGE#1
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From: missing Texas...
yes, you'd have the exhaust shop install the bungs for them so you could re-install 'em, then you'd need a tune to turn off the rears or you could possibly conduct the "Gotts Exhaust mod" and squeeze by without a tune
'97/'03 the fronts ( pre-cats ) can be removed without any CEL issues. The longer set are the actual catalyst units that filter exhaust gases. On the '04/'05 trucks equipped with 4 cat systems, it is vice versa. The front cats are much larger than the '97/'03 pre-cat converters, and they are O2 monitored. The rears are shorter but thicker, and are not O2 monitored.
If you remove the rears and leave the fronts, it may filter alright with old original O2 sensors and trick it to not reading a high gas volume, its a hit or miss.
As mentioned you will need tuned to run catless properly, and to deactivate the rear O2s. Obviously you don't have to worry about emissions checking.
If you remove the rears and leave the fronts, it may filter alright with old original O2 sensors and trick it to not reading a high gas volume, its a hit or miss.
As mentioned you will need tuned to run catless properly, and to deactivate the rear O2s. Obviously you don't have to worry about emissions checking.
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- Confusing ehh.. Nah, no such thing as "pre-cats" on the Fords. Toyota and Audi have something called a pre-cat, but it has a different makeup on the inside vrs a solid converter. Closer to a resonator IMO.Ford F150's 97-2003
Well, starting with the exhaust description:
Constructed of stainless steel.
Has two (2.5 in) pipes with a crossover pipe downstream of the three way catalytic converters (TWCs).
Has one stainless steel muffler that exits in front of the RH rear wheel on the 97's. From 98, I believe they exited behind RH rear wheel. Excluding the lightnings.
Contains dual TWCs.
Has two upstream heated oxygen sensors (HO2Ss) mounted before the TWCs and two catalyst monitor sensors (CMSs) mounted after the TWCs.
____________________
Three-ways have 3 tasks:
First Stage, -Reduction of nitrogen oxides to nitrogen and oxygen:
2NOx → xO2 + N2
Second Stage, -Oxidation of carbon monoxide to carbon dioxide:
2CO + O2 → 2CO2
Third Stage, -Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water:
CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O.
These (three-way) catalyst must run at stoich AFR's. - So that more fuel is consumed than in a lean-burn engine.
Other than that, shoot; - call them any damn thing you want.
BTW- Well, perhaps someone had said this already in this one, if not, you can cut off or gut the first part of the converter w/3/4" auger bit and just run the back portion, - or leave the first converter alone and cut off the longer back converter. Replace w/section of pipe and still remain within factory programed parameter margins. BUT, everything MUST be tight and fairly close to leak free throughout the Y. Otherwise you'll be playing with 420/430 DTC's.
Last edited by jbrew; Jun 3, 2013 at 12:37 PM. Reason: BTW**
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Originally Posted by jbrew
Quote:
Originally Posted by blade11
yeah I've heard they are precats to but then I've heard they are not so idk lol .. hopefully someone can help us out..
- Confusing ehh.. Nah, no such thing as "pre-cats" on the Fords. Toyota and Audi have something called a pre-cat, but it has a different makeup on the inside vrs a solid converter. Closer to a resonator IMO.
The exhaust system: Ford F150's 97-2003 have two 3 stage converters, -one on each side.
Well, starting with the exhaust description:
Constructed of stainless steel.
Has two (2.5 in) pipes with a crossover pipe downstream of the three way catalytic converters (TWCs).
Has one stainless steel muffler that exits in front of the RH rear wheel on the 97's. From 98, I believe they exited behind RH rear wheel. Excluding the lightnings.
Contains dual TWCs.
Has two upstream heated oxygen sensors (HO2Ss) mounted before the TWCs and two catalyst monitor sensors (CMSs) mounted after the TWCs.
____________________
Three-ways have 3 tasks:
First Stage, -Reduction of nitrogen oxides to nitrogen and oxygen:
2NOx → xO2 + N2
Second Stage, -Oxidation of carbon monoxide to carbon dioxide:
2CO + O2 → 2CO2
Third Stage, -Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water:
CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O.
These (three-way) catalyst must run at stoich AFR's. - So that more fuel is consumed than in a lean-burn engine.
Personally, "pre-cats" would be closer to resonators than they would converters. Specially for the TWC systems. Ford didn't use either in this generation of 150's. Not that I know of anyway..
Other than that, shoot; - call them any damn thing you want to lol.
BTW- Well, perhaps someone had said this already in this one, if not, you can cut off or gut the first part of the converter w/3/4" auger bit and just run the back portion, - or leave the first converter alone and cut off the longer back converter. Replace w/section of pipe and still remain within factory programed parameter margins. BUT, everything MUST be tight and fairly close to leak free throughout the Y. Otherwise you'll be playing with 420/430 DTC's.
Originally Posted by blade11
yeah I've heard they are precats to but then I've heard they are not so idk lol .. hopefully someone can help us out..
- Confusing ehh.. Nah, no such thing as "pre-cats" on the Fords. Toyota and Audi have something called a pre-cat, but it has a different makeup on the inside vrs a solid converter. Closer to a resonator IMO.
The exhaust system: Ford F150's 97-2003 have two 3 stage converters, -one on each side.
Well, starting with the exhaust description:
Constructed of stainless steel.
Has two (2.5 in) pipes with a crossover pipe downstream of the three way catalytic converters (TWCs).
Has one stainless steel muffler that exits in front of the RH rear wheel on the 97's. From 98, I believe they exited behind RH rear wheel. Excluding the lightnings.
Contains dual TWCs.
Has two upstream heated oxygen sensors (HO2Ss) mounted before the TWCs and two catalyst monitor sensors (CMSs) mounted after the TWCs.
____________________
Three-ways have 3 tasks:
First Stage, -Reduction of nitrogen oxides to nitrogen and oxygen:
2NOx → xO2 + N2
Second Stage, -Oxidation of carbon monoxide to carbon dioxide:
2CO + O2 → 2CO2
Third Stage, -Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water:
CxH2x+2 + [(3x+1)/2]O2 → xCO2 + (x+1)H2O.
These (three-way) catalyst must run at stoich AFR's. - So that more fuel is consumed than in a lean-burn engine.
Personally, "pre-cats" would be closer to resonators than they would converters. Specially for the TWC systems. Ford didn't use either in this generation of 150's. Not that I know of anyway..
Other than that, shoot; - call them any damn thing you want to lol.
BTW- Well, perhaps someone had said this already in this one, if not, you can cut off or gut the first part of the converter w/3/4" auger bit and just run the back portion, - or leave the first converter alone and cut off the longer back converter. Replace w/section of pipe and still remain within factory programed parameter margins. BUT, everything MUST be tight and fairly close to leak free throughout the Y. Otherwise you'll be playing with 420/430 DTC's.
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