conveters
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From: WEWAHITCHKA FL.
conveters
Hey guys' My catalytic converters are bad on my 03 fx4. It has 4 by the way. If i cut them out and run pipe will it run bad cause of the o2 sensors ? They cost about 800 for both sides to replace them.
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Posting Guru
Joined: Mar 2010
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From: WEWAHITCHKA FL.
CONVERTERS
I just had a new motor put in it and the ford dealer said they were bad. Has no power with the exhaust bolted up tight. So i backed the bolts off at the manifolds and it has power. If i cut them out will it run lean ? Is there anyway to make the C.E.L. go off without converters. Guess what i really need to know whats the cheapest way to fix this problem ? Can i go back with one on each side and keep the C.E.L. off ?
Postmaster
Joined: Nov 2006
Posts: 4,517
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From: SE Wyoming
You need either MIL eliminators for the rear O2's or could probably have a tuner shut them off in a tune. The front sensors control the fueling so missing cats won't cause a problem with the engine running. YOu could also just have $100 high flow cats put in, not sure if the rear O2's would like them or not.
Lead Driver
Joined: Sep 2006
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It should not run lean without the cats because the front OX sensors still control fuel as they always did.
The rear sensors are the ones that monitor the cat performance by looking at the Oxygen content from the cats.
This is done by the computer looking at the 'switching ratio' between the front and the rear OX sensors each side.
When the switch ratio goes out of limits, a code 420 will be set.
Without cats, the code will be set and CEL will aways be on.
Aftermarket direct bolt on cats should be about $350 +/- per side plus labor to install.
Since you have the pipes already loose it a no brainer to do the job.
You 'may' need new Ox sensors if the old ones are damaged from overheating.
Depends on why the cats went bad. If the motor was run with cylinders out, the raw gas burned the cat up and pluigged the flow.
I'm sure you spent a pile of money on the motor, why not finish with new cats and be done with it.
Good luck.
The rear sensors are the ones that monitor the cat performance by looking at the Oxygen content from the cats.
This is done by the computer looking at the 'switching ratio' between the front and the rear OX sensors each side.
When the switch ratio goes out of limits, a code 420 will be set.
Without cats, the code will be set and CEL will aways be on.
Aftermarket direct bolt on cats should be about $350 +/- per side plus labor to install.
Since you have the pipes already loose it a no brainer to do the job.
You 'may' need new Ox sensors if the old ones are damaged from overheating.
Depends on why the cats went bad. If the motor was run with cylinders out, the raw gas burned the cat up and pluigged the flow.
I'm sure you spent a pile of money on the motor, why not finish with new cats and be done with it.
Good luck.
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Posting Guru
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From: WEWAHITCHKA FL.
eliminators
You need either MIL eliminators for the rear O2's or could probably have a tuner shut them off in a tune. The front sensors control the fueling so missing cats won't cause a problem with the engine running. YOu could also just have $100 high flow cats put in, not sure if the rear O2's would like them or not.
Elder User
Joined: Apr 2012
Posts: 990
Likes: 4
From: Tamaroa, IL
You can't just cut the rear sensors out, but there are tricks to fooling the computer. I think some guys even run a resistor in place of them. Some other guys have had luck with the spark plug non-fowler trick. I don't think Ford can shut the rear sensors off, I also don't think that they can legally by-pass such a huge piece of emissions equipment. A local exhaust shop should be able to do the work, or you could do it yourself if you have the right tools.
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Lead Driver
Joined: Sep 2006
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Quite correct, the dealers anywhere, cannot make these alterations legally under the law and large fine if caught.
An after market shop is under the same law.
What you do as an owner is up to you.
If there was a need for emmissions inspection you would still not be able to do it legally with a code showing and hardware missing or altered.
I'm sorry but t cost's too maintain these present day vehichles no matter what make they are.
Good luck.
An after market shop is under the same law.
What you do as an owner is up to you.
If there was a need for emmissions inspection you would still not be able to do it legally with a code showing and hardware missing or altered.
I'm sorry but t cost's too maintain these present day vehichles no matter what make they are.
Good luck.
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Elder User
Joined: Apr 2012
Posts: 990
Likes: 4
From: Tamaroa, IL
This is a great point. If you have to perform any type of emissions testing, there is no way way around having catalytic converters. If you live in a county that doesn't perform any type of emissions testing then you could do away with the system (It's still not legal). A lot of small family owned type exhaust shops will weld pipe in place of your cats (although it's not legal for them to do so).
Cargo Master
Joined: Apr 2001
Posts: 2,220
Likes: 26
It's usually not difficult to remove the exhaust, make at least three legible index marks with a scriber across areas to be cut, so you won't rotate the parts out of line Sawzall forward and aft of the cats, beat out the ceramic with a steel rod, align the index marks, then weld it back together/
Since you can already unbolt the exhaust manifolds, you don't have to worry about wringing off a stud. (Use anti-seize when installing exhaust hardware.)
A 110-volt flux core MIG welder is sufficient.
If you carry the pipe, not the truck, to a welder they may do it for you since the emission system isn't being modified unless you attach the part to the truck itself.
You are of course doing this for Off-Road Use Only.
Since you can already unbolt the exhaust manifolds, you don't have to worry about wringing off a stud. (Use anti-seize when installing exhaust hardware.)
A 110-volt flux core MIG welder is sufficient.
If you carry the pipe, not the truck, to a welder they may do it for you since the emission system isn't being modified unless you attach the part to the truck itself.
You are of course doing this for Off-Road Use Only.
Elder User
Joined: Apr 2012
Posts: 990
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From: Tamaroa, IL
I wouldn't recommend hollowing out the cats. You will then have a big open space in your exhaust system that will screw up your exhaust flow. If your truck has to undergo emissions testing then there is no way around having catalytic converters. If you do not need to perform the testing then you COULD weld exhaust piping (2.5" dia) in place of the cats. You then would have to fool your computer (if you don't want a CEL) for the readings that your rear O2 sensors would give. You could run a resistor in place of the sensor or you could try something like the spark plug non-fowler trick. Those are your options unless you really want to hack your truck back together. If you just spent all that money on an engine swap, you might as well fix the whole thing correctly so you can be happy with your truck.
Cargo Master
Joined: Apr 2001
Posts: 2,220
Likes: 26
In the real world it doesn't change much. One advantage of dumping the fouled ceramic is you can reuse the nice, thick OEM shell rather than the usual thin replacement exhaust pipe.
There are plenty of vehicles out there running just fine with "not theoreticaly ideal" exhaust systems.
One can always try the experiment since it's cheap (if you own or have free access to a welder, it's nearly free) and make up one's own mind on the subject.
There are plenty of vehicles out there running just fine with "not theoreticaly ideal" exhaust systems.
One can always try the experiment since it's cheap (if you own or have free access to a welder, it's nearly free) and make up one's own mind on the subject.
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