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So I'm thinking of de-catting my Rover. However, I was under it the other day, and realized that I have O2 sensors to worry about... Are there any necessary steps I have to take to removing the cats so that the sensors don't freak out on me? If I do just remove them, will the sensors do anything anyway, or will I simply have a little warning message on my dash? I searched but couldn't find anything, however if this has been discussed previously, please just let me know.

Thanks,
 

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Do you have 2 or 4 sensors.
I believe NAS vehicles have 4 so you'll have a message on dash and ECU may go into limp mode
 

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It may be possible to have your "market" changed in the BeCM and have the ECM reset to that of a region where cats are not required. At elast by changing to a market with only two O2 sensors you might be able to remove your follow up sensors.
 

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FWIW, on my Audi, the 2nd pair of o2 sensors is looking to see if the reading is different than the 1st pair of o2 sensors, which would mean the cats are working. So, if you gut the cats, you can put a defouler between the exhaust pipe bung and the o2 sensor (on the 2nd pair) which will take the o2 sensor out of the direct exhaust path, which will trick the 2nd o2 pair into thinking the cat is working. Dunno if that same principle applies here.
 

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As said, only the second pair of O2-sensors, post cat, could cause problems. The front ones will not be affected if you take out the cats.
I've removed the cats on Prue a few years ago (after a blocked cat caused a little fire when running in the camshaft!) and haven't experienced any problems.

What I did was grind open the cats, empty them, put in a piece of pipe (to make sure the empty cats don't act as resonator chambers) and then weld the box closed again.

Greetz,

Filip
 

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do they do emissions testing there?

Here its illegal to decat them, depending on who you talk to, but in general most shops wont touch them.

My 95 is decatted, from the point of view the aftermarket cats broke up after a few years and filled the center box with crud, so I just replaced the center box. I have less low down torque now, to the point I am rather dissapointed, but the value of the car is not worth spending any money on improving it. it could be a combination of decatting and putting on a larger hiflow exhaust, as my center box was full of crud and rusted out at the same time. So I don't know if its just my donk getting tired, or the reduced back pressure causing a big performance hit.
 

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jsp said:
do they do emissions testing there?
Yeah, but nothing directly related to the cats. ;)
Besides, with the single-pont vacuumcontroled LPG system, the cats and O2 sensors don't make much sense anyway.
 

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My other toy is a S/C Cobra, it came with 4 cats. I replaced them with a X-pipe. I've got MIL eliminator plugged into the rear O2 sensors though. Does anyone know if they make these for our Rovers. I guess if you knew the resistance values, you could just wire in a resistor to fool the ECU into thinking they are still working. Just a thought.
 

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I just chimed in on this in the classic forum:


from Rave:
North American Specification (NAS) vehicles have
additional Heated Oxygen Sensors, positioned
downstream of each catalytic converter. The ECM
uses the signals from these sensors to determine
whether the catalysts are working efficiently.
Changing the market should eliminate the use of the downstream sensors by the ECM. If you don't you'll only get the MIL on, no limp-home mode. A failed upstream doesn't give limp-home mode exactly either (like a bad MAF) it just goes open loop which typically over-fuels for safety. Some (Oz maybe?) have no o2's or cats, so run open loop all the time. main difference is higher fuel consumption.

So if it's legal in your area, it's possible. If it's not legal in your area, it's possible IF you're willing to accept the consequences if caught.
 
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