Specifications

76
Data Parameters Engine Parameters
SELF-ADAPTATION IDLE SP. AIR
Range: _____________________________________________ X.XX kg/h or –15 to 15%
Used on LH and HFM systems. This parameter displays the closed throttle position (CTP), or
idle, correction factor that the ECU is commanding to maintain a steady idle. The display for most
systems is in kilograms per hour (kg/h) with zero being the base point. On some HFM systems, a
percentage is displayed. For all systems, negative readings indicate the ECU is decreasing the
idle valve opening and positive values indicate an increase in idle valve opening. The data mass
variable is kilograms per hour (kg/h).
SELF-ADAPTATION, IDLE SPEED
Range: ___________________________________________________ –0.50 to 0.50 ms
Used on SIM4 systems. This fuel trim number represents the fine tuning long-term correction to
the fuel injection pulse width. This type of long term fuel trim adjustment is also called Additive
Mixture Adaptation because it can modify the duration of injection by adding or subtracting to the
base injection time in each fuel map cell (affects all cells by the same amount). It thus affects the
entire engine speed range or all fuel map cells, but is most noticeable at idle because of the
minimal amount of adjustment capability. This number is learned by the ECU and used to correct
small differences between engines and engine wear.
When the short term correction is outside the window defined in the ECU memory, the long term
fuel trim is changed. Each change in the Long Term Fuel Trim is equivalent to a change of the
Short Term Fuel Trim over its entire range. When the Short Term Fuel Trim reaches its upper/
lower limit, it resets back to the beginning, and moves Long Term Fuel Trim up or down by one
count. The Short Term Fuel Trim continues to move very quickly and if the limits are reached, it
again will increment the Long Term Fuel Trim. This continues until either the fuel mixture problem
is corrected or long-term correction reaches its limit and a DTC is set.
SELF-ADAPTATION, IDLE SPEED
Range: ___________________________________________________ –0.50 to 0.50 ms
Used on SIM4 systems. This parameter displays the closed throttle position (idle) fuel correction
to maintain a 14.7:1, or 1.0 Lambda, air-fuel ratio. The display is the adjustment made in addition
to basic injector on time. If short-term fuel trim (STFT) or O2S Lambda control constantly drifts
out of mid-control range, the ME control module shifts this long-term Lambda map to recreate a
control factor of about 0 ms. This is also called Additive Mixture Adaptation because it can
modify the duration of injection by adding or subtracting to the base injection time in each fuel
map cell. It thus affects the entire engine speed range or all fuel map cells, but is most noticeable
at idle because of the minimal amount of adjustment capability.
SELF-ADAPTATION PARTIAL LOAD
Range: ________________________________________________________ –25 to 25%
Used on SIM4 systems. These parameters represent the long-term fuel metering correction
required to maintain a stoichiometric (14.7:1), or 1.0 Lambda, air-fuel ratio. Fuel corrections are
based on the indicated O2S signals and short term fuel trim. Positive readings indicate increased
injector duration to correct a lean condition, and negative readings indicate reduced on time to
correct a rich condition.
This is a long-term correction factor applied to the pre-programmed low partial load base cell
values (original fuel, RPM/Load mapping with no correction).
SELF-ADAPTATION UPPER PART. LOAD
Range: ________________________________________________________0.85 to 1.15
Used on LH systems. This parameter indicates the upper partial load self-adaptation factor,
which is one of three factors that the ECU uses to make long-term fuel trim (LTFT) corrections to
maintain a 14.7:1, or 1.0 Lambda, air-fuel ratio. On the display, a 1.0 reading is the base point.
Readings over 1.0 are a rich correction, or increased injector time and readings lower than 1.0