LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Jeep >> 1981 >> Cherokee Base, 2D Utility, 4.2L Eng VIN C, AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Computerized Emission Control >> Operation >> Micro Computer Unit (MCU) >> Closed Loop
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Closed Loop

When all input data and engine operation meet programmed criteria (after OL1, OL2, OL3 and OL4 modes have been selected and start-up timer has deactivated), the CEC system goes into closed loop operation. In this mode, oxygen sensor input signals are accepted by MCU to determine proper air/fuel mixture based upon oxygen content of exhaust gases. Air injection is routed "downstream" during this mode to aid in oxidation of HC and CO. The predetermined "lean mixture ceiling" is selected for a preset length of time at the start of closed loop operation.

NOTE: Closed loop operation is characterized by constant movement of the metering pins. The MCU is constantly making small corrections in air/fuel ratio in an attempt to create the ideal air/fuel ratio.
scientia non olet · About LEMON Manuals