klivito8

Hey, do any of you know if you have a ECU tune already for long tube headers and you Weld in sport cats just to pass MOT and then remove them after Will there be any problems with the tune? Thanks guys

catmandoob

I wouldn't imagine so, so many of the canned tunes so to speak let the bosch ecu do most the work anyway. You'll be fine, now how to resolve the downstream O2 sensor that's disabled, that's another obstacle and yes it would take a tune to turn it back on for emissions check.

roadkillrob

And if you weld in sport cats and turn the 02 monitors back on in the tune you will likely want some 2" spacers on the rear 02's so that you don't get a code - seems it doesn't take much, I had 200 cell sport cats on mine and a 2" spacer on the rear 02's and never ever had a code or an emission issue, they are just the open spacers nothing special not even the mini cat ones, these cars are super easy to get the 02's to be happy unlike most BMW's that are way harder.

eightysixtuned

a tune for LTH without cats will mark the catalyst and secondary oxygen sensors as N/A thus failing you even if you have catalytic converters in most placed that do smog checks.

klivito8

hmm okay. So what would you suggest i do?

DRBC43AMG

Leave the cats installed and be done with it. Nature will appreciate the cleaner air

eightysixtuned

if you are able to flash back to the factory tune, do that. no tuner should ever sell a tune without allowing the customer to revert fully back to stock. that is just bad business practice.