MOTRONIC System
The MOTRONIC TROUBLE SHOOTING CHART can be helpful in diagnosing problems related to the Motronic engine control system. This chart should be used before proceeding to the TESTING section.
TROUBLE SHOOTING
| Condition | Possible Cause |
|---|---|
| Cold Engine Will Not Start | Fuel Pressure, Fuel Injector, Cold Start Valve, Motronic Control Unit, Speed Transmitter, Reference Mark Transmitter, Air Flow Sensor, Wire Connections and Plugs, Ignition Coil |
| Cold Engine Starts, But Stalls | Fuel Injector, Motronic Control Unit, Wire Connections and Plugs, |
| Cold Engine Hard to Start | Fuel Pressure, Temp. Time Switch, Motronic Control Unit, Cold Start Injector, High Voltage Distributor, Spark Plugs, Temp. Time Switch |
| Warm Engine Will Not Start | Fuel Pressure, Fuel Injector-Motronic Control Unit, Speed Transmitter, Reference Mark Transmitter, Wire Connections and Plugs, Ignition Coil, Secondary Air of Engine |
| Erratic Idle/Warm-Up Phase | Throttle Switch, Coolant Temp. Sensor, Idle Valve, Motronic Control Unit, Throttle Switch, Air Temp. Sensor, Temp. Switch 112° (45°C), Wire Connections and Plugs, High Voltage Distributor, Spark Plugs, Ignition Circuits, Intake System, Coolant |
| Engine Backfiring | Fuel Injector, Motronic Unit, High Voltage Distributor, Spark Plugs, Ignition Circuit, Exhaust System |
| Idle Speed Incorrect | Fuel Injector, Cold Start Injector, Motronic Control Unit, Intake System, Throttle Switch, Temp. Time Switch, Coolant Temp. Switch, High Voltage Distributor |
| Acceleration Hesitation | Fuel Injector, Motronic Control Unit, Wire Connections, High Voltage Distributor, Spark Plugs, Ignition Circuit |
| Acceleration Knock | Motronic Control Unit, Wire Connections, Spark Plugs, Ignition Circuit |
| Coasting Hesitation | Fuel Injector, Motronic Control Unit, Wire Connections and Plugs |
| Engine Misfiring All Conditions | Fuel Injectors, Motronic Control Unit, Wire Connections and Plugs, Ignition Circuit, Intake System, Exhaust System, Secondary Air of Engine, Coolant, Insufficient Engine Power, Fuel Injector, Fuel Pressure, Motronic Control Unit, Air Flow Sensor, Throttle Switch, Coolant Temp. Sensor, Air Temp. Sensor, Ignition Circuit, Intake and Exhaust System |
| High Fuel Consumption | Fuel Injector, Cold Start Injector, Motronic Control Unit, Throttle Switch, Temp. Time Switch, Coolant Temp. Sensor, Air Temp. Sensor |
| CO Level Incorrect | Fuel Injector, Cold Start Injector, Oxygen Sensor, Wire Connections and Plugs, Intake System, Secondary Air of Engine |
| HC and NO(x) Excessive | Fuel Injector, Cold Start Injector, Motronic Control Unit, Oxygen Sensor, Wire Connections and Plugs, Intake System, Secondary Air of Engine |