Here is 1987-90 Jeep YJ Wrangler and Jeep XJ Cherokee/MJ Comanche 2.5L TBI diagnostics information in PDF form.  The first document includes all sensor and switch tests plus adjustments that affect engine tune, idle and reliability.  Wiring schematics and ECU pin locations, test plugs and diagnostics included. Jeep 2.5L TBI Complete Diagnostics-Sensors-Switches.pdf Jeep 2.5L TBI ECU Inputs and Outputs.pdf Jeep 2.5L TBI MAP Sensor Test.pdf Jeep 2.5L Timing Chain and Tensioner.