Has anyone with a F56 cooper s gone catless without a tune and for how long after catless did you get the tune?

 

Trying to understand the reason for the question

But I've been tuned and even on stock ecu tune catless for various lengths of time with no issues. You just get a check engine light because of the o2 sensor readings. No other issues

 

I'm a little perplexed by the folks that accept the MIL from a cat delete. They remove the catalytic converter and replace with a blank downpipe. Reinstall the O2 sensors in the new downpipe in the OEM positions. The bank 1 sensor is doing it's OEM job and reflecting emissions from the exhaust. The bank 2 sensor is doing it's OEM job and checking the post cat emissions. The MIL comes on during engine idle because fumes can collect in that standoff that reflect the absence of a catalytic converter and the standoff for the bank 2 O2 sensor is at a height hopefully sufficient to fool the O2 into thinking that the emissions are cleaned up but it can't due to design under certain engine conditions. Why would you expect the O2 sensor not to throw the code? If the bank 2 sensor is effectively just window dressing, why is it in it's stock position?

How do you resolve this? Fire the bank 2 O2 sensor from it's day job! Cap the hole in the new downpipe. What to do with the bank 2 O2 sensor? Option 1: If you want to leave the sensor in, tie it up in a spot that allows it to function in the open air. Your ECU now thinks you have the best operating catalytic converter on the planet. Option 2: if you know the numeric values of the wiring and what resistance the ECU is looking for, wire a resistance dummy at the end of the OEM bank 2 plug and put the O2 sensor in your toolbox.

The decat is something we do for engine air movement presumably for better performance. The only reason the MIL is a problem is because this is a daily driver and some states run emissions standards during state inspections. If its a true track car meant for offroad, get a flash tuen that deleted the O2 sensor functions or changes the tables in such a way that the MIL doesn't come on. I've seen plenty of track tuned cars that are only for tracks with the MIL living it's happy life until the bulb or LED finally gives out.

Did I miss something?

 

Get O2 simulator or spark plug defouler. I did this on my car with JB4 and catless DP

 

I've run the defouler in V8's on US motors and I've capped and tied off the unused O2 in the past. Both appeared to have the same result. I just can't fathom why some of these guys run with a MIL on the car and call it a day...