Originally posted by ijames
Disconnecting the puck will give you virtually no boost and it will take forever to spool up, so I'd say no boost at all on the dyno (not that they should ever need to mash hard enough to make boost anyway, but the idiots here like to use the floor it-lift completely method of driving, sigh). When you get past a little boost (2-4 psi depending on several things) the ecm goes into power enrichment mode and adds fuel, which kills your emissions (some HC, lots of CO). You want to stay out of that mode for the test, but again, that depends on the operator but disconnecting the rod will help.