Adaptive Idle

Purpose and Operation
In order to ensure optimum performance, PCME automatically trims fuel injector ON time at idle, throughout the life of the vehicle. 20 % is total available trim to injector ON time. Adaptive fueling is performed by PCME only when listed diagnostic trouble codes (DTCs) are cleared and listed preconditions are met.

Diagnostic codes that must be cleared for adaptive idle fueling to occur are:
12 Mass air flow meter
14 Coolant temperature sensor
17 Throttle potentiometer
18 Throttle potentiometer and mass air flow meter calibration
19 Throttle potentiometer and mass air flow meter calibration
23 Fuel supply
26 Oxygen sensor feedback (lean)
34 Injectors
37 EGR drive
39 EGR temperature sensor
44 Oxygen sensor
48 Idle speed control valve
68 Road speed sensor
89 Purge valve drive

Preconditions:
Throttle is closed
Engine speed below 1000 rpm
Road speed below 3 mph (6 kph)
Engine coolant temperature above 170° F (76°C)
Idle speed adaptive delay is complete (vehicle speed reached 3 mph for approximately 100 yards traveled)
Closed-loop fueling is operating and in control
Integrator voltage less than two volts or greater than three volts

If DTC's are cleared and preconditions are met, PCME cancels purge flow and adapts idle fueling. Between fueling adaptations, there is a delay of approximately eight minutes furing which preconditions must be met. If preconditions are interrupted, delay will be longer.