SYMPTOMS
Note. Some driveability problems may have been corrected by manufacturer with a revised Electrical Control Module (ECM). Check with manufacturer for latest computer application.
Symptom checks can direct the technician to malfunctioning component(s) for further diagnosis. A symptom should lead to a specific component, system test, or adjustment.
Use intermittent test procedures to locate driveability problems that DO NOT occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present, but no problem was found during self-diagnostic testing.
Note. For specific testing procedures, see SYSTEM/COMPONENT TESTS article. For specifications, see ADJUSTMENTS or SPECIFICATIONS article.
| Symptom | (1) Possible Cause |
|---|---|
| Engine Stalls During Idle | Idle Air Control Solenoid Valve, Mass Airflow Sensor, (2) Ignition Parts, (3) Engine Coolant Temp. Sensor, (4) Crankshaft Position Sensor, (4) Camshaft Position Sensor, EGR Valve, (5) Fuel Injection Components |
| Rough Idle | Idle Air Control Solenoid Valve, Mass Airflow Sensor, (3) Engine Coolant Temp. Sensor, (2) Ignition Parts, (6) Air Intake System, (5) Fuel Injection Components, Throttle Position Sensor, (4) Crankshaft Position Sensor, (4) Camshaft Position Sensor, EGR Valve, Oxygen Sensor |
| Engine Does Not Return To Idle | Idle Air Control Solenoid Valve, Engine Coolant Temp. Sensor, (7) Accelerator Cable, Throttle Position Sensor, Mass Airflow Sensor |
| Poor Acceleration | Mass Airflow Sensor, Throttle Position Sensor, (5) Fuel Injection Components, Fuel Pump, Fuel Pump Relay, (3) Engine Coolant Temp. Sensor, (4) Crankshaft Position Sensor, (4) Camshaft Position Sensor, A/C Switch, A/C Relay, Engine Torque Control Signal Circuit, (2) Ignition Parts |
| Engine Stalls, Sags Or Hesitates During Acceleration | Mass Airflow Sensor, (3) Engine Coolant Temp. Sensor, (4) Crankshaft Position Sensor, (4) Camshaft Position Sensor, Purge Control Solenoid Valve, EGR Valve, (5) Fuel Injection Components, Throttle Position Sensor, Fuel Pump, Fuel Pump Relay |
| Surge | Mass Airflow Sensor, (2) Ignition Parts, (3) Engine Coolant Temp. Sensor, (4) Crankshaft Position Sensor, (4) Camshaft Position Sensor, EGR Valve, (5) Fuel Injection Components, Throttle Position Sensor, Fuel Pump, Fuel Pump Relay |
| Spark Knock | Mass Airflow Sensor, (3) Engine Coolant Temp. Sensor, Knock Sensor, (5) Fuel Injection Components, Fuel Pump, Fuel Pump Relay |
| After-Burn In Exhaust System | Mass Airflow Sensor, (3) Engine Coolant Temp. Sensor, (5) Fuel Injection Components, Fuel Pump, Fuel Pump Relay |
| (1) Check possible causes in order listed. (2) Check ignitor, ignition coil and spark plugs. (3) If symptom occurs only in cold temperatures. (4) Ensure component is securely installed. (5) Check fuel injectors, fuel pressure regulator and fuel filter. (6) Check for air leak(s) in air intake system. (7) Adjust accelerator cable. | |
| (1) | Check possible causes in order listed. |
| (2) | Check ignitor, ignition coil and spark plugs. |
| (3) | If symptom occurs only in cold temperatures. |
| (4) | Ensure component is securely installed. |
| (5) | Check fuel injectors, fuel pressure regulator and fuel filter. |
| (6) | Check for air leak(s) in air intake system. |
| (7) | Adjust accelerator cable. |
SYMPTOM DIAGNOSIS CHART
INTERMITTENT PROBLEM DIAGNOSIS
Intermittent fault testing requires duplicating circuit or component failure to identify problem. These procedures may lead to the computer setting a fault code, which may help in diagnosis.
If problem vehicle does not produce fault codes, monitor voltage or resistance with a DVOM while attempting to reproduce the conditions causing intermittent fault. A status change on DVOM indicates a fault has been located.
Use a DVOM to pinpoint faults. When monitoring voltage, ensure ignition switch is in ON position or engine is running. Ensure ignition switch is in OFF position, or negative battery cable is disconnected when monitoring circuit resistance. Status changes on DVOM during test procedures indicate area of fault.