I have an 06 evo IX MR, LC1 cable just arrived from Innovate Motorsports, Im getting ready to install the kit, but I lifted my car to see if my DP had a bung already for the sensor, nope, so I am going to be getting one soon. My question is, when I had my car lifted, my exhaust has two o2 sensors already, one on top of the cat that is wired up through the car (not sure if its plugged in to anything inside yet) and another o2 sensor just after the cat, but the wires are cut so its not doing anything (pictures below), I plan on tuning the car myself, so will I need all 3 sensors? should I get a high-flow cat without a sensor, and leave the one behind it and just replace the sensor? or keep the cat sensor and get the third one removed? or keep all 3 after my DP is installed?

 

The front O2 sensor monitors fuel trims for your gas mileage and drive ability. Its needed. The second one is to monitor the efficiency of the catalytic converter and emissions. If you have emissions testing then you would need to alter your rom to reflect that you are eliminating the sensor. Not to be an a**hole but tuning requires a lot of reading and understanding of what the sensors on your vehicle do. Tuning should only be done by a professional on a safe road. The basics being able to tell what those sensors do. Be VERY VERY careful with the tuning you attempt to do or you will cause serious damage to the engine and/or other sensors on the car.

 

I have been reading about it a lot, but I still have a lot to learn I have read about needing two o2 sensors, one on the DP before the cat that's a wideband for air/fuel ratio adjusting and such, and one after the cat to measure efficiency like you said, just never read about one on the cat itself. So am I to understand that all three o2 sensors (before cat, on cat, and after cat) are needed? high flow cat will need a bung welded into it? That I need to replace the third o2 sensor since the wires for it seem to have been cut?

Thanks again for your time

 

car upside down = bigger problem