Originally Posted by Duhfactor
O.K. my friend, I know you have experience with this, help a brother out? Help me understand.....
L maps work off of manifold pressure(more active with quick throttle movement and low TPS). F maps are TPS(active with steady state throttle). The switchover point is NOT set in stone with the F-L map. You can take the FL point down to 1800rpm yet the L map will still be active when you hit it hard like an accel pump. If you lean the L maps your acceleration inreachment will suffer. When tuning on a dyno you hold a load on an engine at steady throttle. So, say your loading the engine at 20%TPS and 3,500RPM. You add fuel until you reach peak hp. At that point that is all the fuel the engine needs. Now lets say you cruising down the road at 20%TPS and 3,500rpm. You know your bike is at max hp with the map you just did. You nail the throttle to do a wheelie past all the BMW's sitting at the Starbucks. The engines load suddenly changes as the throttles open. Can't think of the term but what happens is the new fuel charge tends to stick on the walls of the intake manifold and in the cylinder for a split millisecond. As this happens you can see where the A/F ratio will go lean. This is why the L maps take over and add more fuel to account for the loses until things catch up.