How to use support material and still get very accurate parts

[Malty2 0]

I wanted to ask about support material for our printer. I want to print accurate prints using engineering profile and still use support material but we currently only have PVA which from what I have read is only usable with a BB core. The problem for me is I have to turn off the extruder with that core or I can't use the engineering profile. Is there a support material I can use with a AA core or is there another way round using a BB core and still use the engineering profile? 

[Smithy 1,144]

You can use the engineering profile with dual extrusion and the BB core with PVA for your support.

 

 

Can you explain it a bit more what should not work? 

I guess you have selected maybe a not supported material or a combination.

[Malty2 0]

I always get this message when I try and do the engineering profile the only way I can get to remove this is turning off extruder 2. Do I need to change any other settings?