* PLEASE READ THIS FIRST *
Note. This article is generic in nature and all information does not apply to all vehicles. For vehicle specific information, see the appropriate articles in the ENGINE PERFORMANCE category.
Note. This article is generic in nature and all information does not apply to all vehicles. For vehicle specific information, see the appropriate articles in the ENGINE PERFORMANCE category.
| Problem & Possible Cause | Action | ||
|---|---|---|---|
| Carbon Fouled Plugs | |||
| Clogged Air Filter | Replace Air Filter | ||
| Incorrect Idle Speed | Reset Idle Speed | ||
| Faulty Ignition Wiring | Replace Ignition Wiring | ||
| Sticky Valves/Worn Valve Seal | Check Valve Train | ||
| Fuel Injection Operation | Check Fuel Injection | ||
| Wet/Oil Fouled Plugs | |||
| Worn Rings/Pistons | Overhaul/Replace Engine | ||
| Excessive Cylinder Wear | Overhaul/Replace Engine | ||
| Plug Gap Bridged | |||
| Combustion Chamber Carbon Deposits | Clean Combustion Chamber | ||
| Blistered Electrode | |||
| Engine Overheating | Check Cooling System | ||
| Loose Spark Plugs | Clean/Torque Plugs | ||
| Over-Advanced Timing | Reset Timing | ||
| Wrong Plug Heat Range | Install Correct Plug | ||
| Melted Electrodes | |||
| Incorrect Timing | Reset Timing | ||
| Burned Valves | Replace Valves | ||
| Engine Overheating | Check Cooling System | ||
| Wrong Plug Heat Range | Install Correct Plug | ||
| Engine Won't Start | |||
| Loose Connections | Check Connections | ||
| No Power | Check Fuses/Battery | ||
| Loose/Worn Timing Belt/Chain/Gears | Check Belt/Chain/Gears | ||
| Engine Runs Rough | |||
| Leaky/Clogged Fuel Injectors | Repair Fuel Injectors | ||
| Leaky/Clogged Fuel Lines | Repair Fuel Lines | ||
| Clogged Fuel Filter | Replace Fuel Filter | ||
| Incorrect Timing | Reset Timing/Check Advance | ||
| Faulty Plugs/Wires | Replace Plugs/Wires | ||
| Uneven Compression | Overhaul/Replace Engine | ||
| Poor Acceleration | |||
| Incorrect Ignition Timing | Reset Timing | ||
| Leaky Valves | Check Compression | ||
| Component Failure | |||
| Spark Arcing | Replace Faulty Part | ||
| Defective Pick-Up Coil | Replace Pick-Up Coil | ||
| Defective Ignition Coil | Replace Ignition Coil | ||
| Defective Control Unit | Replace Control Unit | ||
| Ignition Diagnosis By Scope Pattern | |||
| All Firing Lines Abnormally High | |||
| Retarded Ignition Timing | Reset Ignition Timing | ||
| Lean Air/Fuel Mixture | Adjust Fuel Mixture | ||
| High Secondary Resistance | Repair Secondary Ignition | ||
| All Firing Lines Abnormally Low | |||
| Rich Air/Fuel Mixture | Adjust Air/Fuel Mixture | ||
| Arcing Coil Wire | Replace Coil Wire | ||
| Cracked Coil | Replace Coil | ||
| Low Coil Output | Replace Coil | ||
| Low Compression | Check/Repair Engine | ||
| Several High Firing Lines | |||
| Fuel Mixture Unbalanced | Check Fuel System | ||
| EGR Valve Stuck Open | Clean/Replace EGR Valve | ||
| High Plug Wire Resistance | Replace Plug Wire | ||
| Cracked/Broken Plugs | Replace Plugs | ||
| Intake Vacuum Leak | Repair Leak | ||
| Several Low Firing Lines | |||
| Fuel Mixture Unbalanced | Adjust Fuel Mixture | ||
| Plug Wires Arcing | Replace Plug Wires | ||
| Cracked Coil Arcing | Replace Coil | ||
| Uneven Compression | Check/Repair Engine | ||
| Faulty Spark Plugs | Replace Plugs | ||
| Cylinders Not Firing | |||
| Cracked Distributor Cap | Replace Cap | ||
| Shorted Plug Wires | Replace Plug Wires | ||
| Mechanical Engine Fault | Check/Repair Engine | ||
| Spark Plugs Fouled | Replace Plugs | ||
| Carbon Track in Distributor Cap | Replace Cap | ||
| Hard Starting | |||
| Defective Ignition Coil(s) | Replace Coil(s) | ||
| Fouled Spark Plugs | Replace Plugs | ||
| Incorrect Timing | Reset Ignition Timing | ||
TUNE-UP TROUBLE SHOOTING
Note. This article is generic in nature and all information does not apply to all vehicles. For vehicle specific information, see the appropriate articles in the ENGINE PERFORMANCE category.
| Problem & Possible Cause | Action | |
|---|---|---|
| Cold Start Valve Inoperative | Test Cold Start Valve | |
| Poor Vacuum/Electrical Connection | Repair Connections | |
| Contaminated Fuel | Test Fuel for Water/Alcohol | |
| Bad Fuel Pump Relay/Circuit | Test Relay/Wiring | |
| Battery Voltage Low | Charge/Test Battery | |
| Low Fuel Pressure | Test Press. Regulator/Pump | |
| No Distributor Reference Pulse | Repair Ignition System | |
| Coolant Temp. Sensor Defective | Test Temp. Sensor/Circuit | |
| No Power To Injectors | Check Injector Fuse/Relay | |
| Hard Starting | ||
| Defective Idle Air Control (IAC) | Test IAC and Circuit | |
| EGR Valve Open | Test EGR Valve/Control Circuit | |
| Restricted Fuel Lines | Inspect/Replace Fuel Lines | |
| Poor MAP Sensor Signal | Test MAP Sensor/Circuit | |
| Engine Stalls During Parking Maneuver | Check P.S. Press. Switch | |
| Rough Idle | ||
| Dirty Fuel Injectors | Clean/Replace Injectors | |
| Poor MAP Sensor Signal | Test MAP Sensor/Circuit | |
| Intermittent Fuel Injector Operation | Check Harness Connectors | |
| Erratic Vehicle Speed Sensor Inputs | Harness Too Close to Plug Wires | |
| Poor O 2 Sensor Signal | Test O 2 Sensor/Circuit | |
| Faulty PCV System | Check PCV Valve and Hoses | |
| Poor Acceleration | ||
| Weak Fuel Pump | Replace Fuel Pump | |
| Dirty Fuel Injectors | Clean/Replace Injectors | |
| Excessive Intake Valve Deposits | Clean Intake System | |
| Poor High Speed Operation | ||
| Low Fuel Pump Volume | Faulty Fuel Pump/Filter | |
| Poor MAP Sensor Signal | Test Speed Sensor/Circuit | |
| Acceleration Ping/Knock | ||
| Faulty EGR System | Check EGR Valve and Hoses | |
| Poor Knock Sensor Signal | Test Knock Sensor/Circuit | |
| Poor Baro Sensor Signal | Test Baro Sensor/Circuit | |
| Improper Ignition Timing | Adjust Timing | |
| Engine Overheating | Check Cooling System | |
| Poor Quality Fuel | Use Different Fuel | |
| Carbon Build-Up | Decarbon Engine | |
FUEL INJECTION TROUBLE SHOOTING