There is a bit of confusion over the different modes the computer can enter so im going to try and clear this up for everyone.

MAF Closed Loop-MAF is Active, Main fueling O2 sensors are Active
  • Most I4's run in this mode, corrections are made by the MAF, VE table & O2 sensors at part throttle
MAF Open Loop-MAF is Active, Main fueling O2 sensors are Inactive or removed
  • Many use this mode when the o2 sensors cannot be trusted for whatever reason ie Big cam(s), LT's, etc.
Speed Density Closed Loop(OLSD or SDOL)-Maf is inactive, removed or Failed, Main fueling O2 sensors are Active
  • Many revert to this mode after doing VE tuning in SDOL mode so the computer can make some corrections for fueling
Speed Density Open Loop-Maf is inactive, removed or Failed, Main fueling O2 sensors are Inactive
  • Most will say this is best for VE tuning because you have complete control over what the engine wants to do.
  • Setup your OLFA tables as you'd like to drive around town
  • Setup your PE tables as you'd like to drive around town
  • Just remember the computer will always command whatever table is richest so keep an eye on any adder/multiplyer tables that may be in effect such as Cat Over Temp.
Bottom Line is to remember Is Speed Density mode doesnt dictate if your in Open Loop or Closed Loop.