Trim 2 rich/Trim 2 lean feature to tune CO?

Will tuning the "Trim 2 lean" reduce exhaust CO content at idle speed?

My understanding is that it just adjusts the openloop mixture the same as the openloop lean and rich.
It appears to have that effect.
If anyone knows better then I would like to hear it.

jonaf wrote: Will tuning the "Trim 2 lean" reduce exhaust CO content at idle speed?

Are you trying to reduce emissions for your MOT test?

I was wondering if the Trim 2 was for tuning the fuelling in closed loop mode. It would be nice to be able to to tweak the mixture to make it pass MOT with a poor catalyst.
My MGF passed the test with 0.2% CO so I think the cat is OK.
After doing some testing with the Trim 2 buttons with my Gunson analyzer connected I found that they work in open loop only i.e just the same as the Open loop rich/lean buttons.

Yes it appears that it is just a second method in the diagnostic protocol for adjusting the same thing. That was my conclusion.