O2 sensor catalitic convertor....
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Freshman User
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From: DC
O2 sensor catalitic convertor....
thinking about taking out my cats ... i got one then my O2 sensor then another should i worry about my engine performance with my CPU and how it reads if i take both out or should i do just one .. has ayone else done this ?
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From: Gateway to the West
Aside from the fact that its illegal to remove an working catalytic converter I doubt you have a cat THEN an O2 sensor, the heat generated by a catalytic converter would render an O2 sensor useless if it was immediately behind the cat. What model year Bronco are we talking about here? Which engine?
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Cats
Greystreak is correct, the O2 sensor is usually located on the lead pipe from the exhaust manifold, they are crucial to engine performance, I also have a 5.0 Mustang that after a major tune up still wouldn't run good at all until I replaced the O2 sensors (5.0 Mustangs have 2, one on each lead pipe) then it ran great! You can replace the cats with one high performance one if yours are bad, as Greystreak pointed out it's illegal to remove cats unless they are bad and are replaced with a DOT legal one, there are high performance single ones that are, Google search you'll find them. Fleet
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You shouldn't have to worry about the cat/cats affecting the oxygen sensor, if your Bronco is an 87 as your profile reads. The only Bronco that might have a problem with this would be a 96, because of the OBDII computer change. If it is 95 or older there won't be a problem. As long as it is before the cats then it doesn't matter. This means between the motor and the cat. Your Bronco might have a different setup if it is a Califrornia vehicle.
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From: Gateway to the West
96 models just have two more O2 sensor thats the only difference in the actual exhaust. They are still IN FRONT of the cats. A properly functioning catalytic converter will ruin an O2 sensor if its mounted dowstream of the cat in the exhaust. (I guess maybe I'm speaking some foreign language here). Disemboweling or removing a catalytic converter does not reduce restriction within the exhaust a notable amount. You would be better off keeping the truck legal and running a larger diameter pipe and a high flow cat. Reduce the restriction in the exhaust too much and you lose valuable back pressure and torque which translates to a loss of power.
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From: DC
by the way it is a 87 with a 5.0, it goes CAT , O2 , CAT then sum exhaust with a flowmaster. if i take one out which would be better to remove or if i put a high performance one in , should i put it in front of or behind hte O2 sensor ? thanks for all your responses
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From: VB. Virginia
My sons 98 Ranger with a 2.5 liter 4cyl. has a O2 sensor in the exhaust manifold and a second 02 sensor 9" behind the cat. it is checking to see if the cat is reducing emissions to within a given spec. if not the second 02 sensor will trip the check engine light.
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Are you the original owner of the Bronco/do you know if anything has ever been replaced in the exhaust. Obviously the flowmaster might not have been the only previous change down there. However unlikely, are you sure your not confusing the O2 sensor with the air injection tube?
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From: Groton, CT
Originally Posted by greystreak92
96 models just have two more O2 sensor thats the only difference in the actual exhaust. They are still IN FRONT of the cats. A properly functioning catalytic converter will ruin an O2 sensor if its mounted dowstream of the cat in the exhaust. (I guess maybe I'm speaking some foreign language here). Disemboweling or removing a catalytic converter does not reduce restriction within the exhaust a notable amount. You would be better off keeping the truck legal and running a larger diameter pipe and a high flow cat. Reduce the restriction in the exhaust too much and you lose valuable back pressure and torque which translates to a loss of power.
The third O2 sensor is known as a "downstream monitor" with the OBD II system and is mounted in the system about 6" AFTER the second cat. You will only find this configuration in OBD II compliant vehicles. With the proximity of the pipe to the E4OD tranny, makes changing that one out an adventure.
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From: Groton, CT
OOPS, now I spoke incorrectly. Just came in from the driveway where I was continuing my search for an elusive exhaust leak. The downstream monitor O2 sensor is after the first cat but BEFORE the second one. The third sensor is just forward of the air injection tube. So the pattern goes:
Sensor in manifold (both sides)
First Cat (at the Y)
Third O2 Sensor
AIR Injection
Second cat.
My question for the original problem would be this:
Does your truck still have the original motor and exhaust. For an 87 to have this setup I would initially suspect that a 96 Y pipe or a whole 96 motor was swapped in. Otherwise it does not make any sense to have this setup in a 87.
Sensor in manifold (both sides)
First Cat (at the Y)
Third O2 Sensor
AIR Injection
Second cat.
My question for the original problem would be this:
Does your truck still have the original motor and exhaust. For an 87 to have this setup I would initially suspect that a 96 Y pipe or a whole 96 motor was swapped in. Otherwise it does not make any sense to have this setup in a 87.