Running rich with decats?

[Jhonno]

Refitted my decats having run the cats for the MOT and now it smells very rich..? Anyone come across this before?! With the cats it flew through emissions..

[Jhonno]

It had the throttles set up with the decats in btw.. You can taste the Super in the fumes on idle.. Fast idle though it will nearly creep through the emissions with the decats, but the levels are through the roof on idle.

[ridds]

That's because your cats are no longer mopping up the unburnt HCs.

Which is what they were there to do.

[Jhonno]

Fair enough.. As long as it is normal behaviour! Didn't realise it would be such an "extreme" difference..