I have a 1995 Mercury cougar XR7 with the 4.6. I want to cut the cats off but there is O2 sensors before the cats and behind them. What will happen if i cut the cats off? will it just turn the check engine light on or will it does it screw with the fuel mixture or anything like that? any help would be appreciated

thanks

I'm not sure about emissions laws in your State, but you'll find that you can't simply cut the cats off. anyhow - that point aside, you will need the HEGO sensors!! You might want to go to an exhaust shop and have them relocate the HEGO sensors somewhere else in your system.

Without the HEGO sensors your car will probably run very rich.

Hey mate.

Yeah setups like that have an oxy sensor either side of the cats in order for the ECU to ensure the cats are working effectively.

You cant really remove any oxygen sensors from the equation - ECU uses these readings when cruising to achieve a targeted air/fuel ratio.

If you must remove the cats, can you just weld in some tubing thru the middle of them?

As for the readings your ECU will get after doing so... anyone's guess! I imagine it would simply throw you a fault code saying "the cats are buggered"... which im sure would be of no suprise, lol.

EDIT: *4.9 EF Futura does not condone removing emission control devices*