Engine Controls - Tests W/o Codes: Other Jeep Cherokee III

ENGINE DOES NOT START

If engine cranks but does not start or engine does not start and DRB displays no response, see NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES article.

HARD START

Check listed items as follows

1. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
2. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
3. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
6. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.
8. Check intake air temperature sensor. See CHECKING INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.

STARTS & STALLS

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
6. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.

HESITATION/STUMBLE

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
6. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
8. Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.
9. Check intake air temperature sensor. See CHECKING INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.

SURGE

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor calibration. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
6. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
8. Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.

LACK OF POWER/SLUGGISH

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
6. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.

SPARK KNOCK/DETONATION

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
6. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
8. Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.

CUTS OUT/MISSES

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
4. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.

BACKFIRE

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.

RUNS ROUGH/UNSTABLE, ERRATIC IDLE

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. Check manifold absolute pressure sensor. See CHECKING MAP SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
6. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
8. Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.
9. Check intake air temperature sensor. See CHECKING INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.

POOR FUEL ECONOMY

Check listed items as follows

1. Check Powertrain Control Module (PCM) power and ground circuits. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in SYSTEM & COMPONENT TESTING article.
2. Check fuel pressure. See FUEL PRESSURE TEST under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES article.
3. Check engine coolant temperature sensor. See CHECKING ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
4. Check throttle position sensor. See CHECKING THROTTLE POSITION SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.
5. On models with 45RFE transmission, check minimum idle airflow. See CHECKING MINIMUM AIRFLOW under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
6. Check idle air control motor operation. See CHECKING IDLE AIR CONTROL MOTOR under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING article.
7. Check EVAP emission system. See FUEL EVAPORATIVE SYSTEM in SYSTEM & COMPONENT TESTING article.
8. Check intake air temperature sensor. See CHECKING INTAKE AIR TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article.

Intermittent Simulation

To reproduce the conditions creating an intermittent fault, use the following methods

1. Lightly vibrate component.
2. Heat component.
3. Wiggle or bend wiring harness.
4. Spray component with water.
5. Remove/apply vacuum source.

Monitor circuit/component voltage or resistance while simulating intermittent conditions. If engine is running, monitor for DTCs. Use test results to identify a faulty component or circuit.