AEM 30-6905 Universal Programmable EMS-4 - Manual (Page 163)

Page 163 of 279 EMS-4 Install and Tuning Guide_Rev 1.6
The Air Temp Fuel Trim table is used to compensate for air density changes with inlet air
temperature. It can also be used in a safety mode to add additional cooling fuel at very high
inlet air temperatures on boosted applications.
The Boost Fuel Trim table is used to add a fuel compensation vs engine manifold pressure.
This table can be used in a number of ways. It can be used to compensate for boost pressure
on a calibration file set up in Alpha-N mode or throttle based fueling or it can be used on a file
set up using manifold pressure as the primary load input.
Tuning Tip - The Boost Fuel Trim table can be used to simplify the main fuel map tuning
under boosted conditions. As a rule of thumb, 100% additional fuel compensation can
be added for every additional Bar of boost pressure as shown in the image below: