Engine Symptoms (760) 741-7861

Cadillac


Engine Performance Trouble Shooting

The Symptoms listed below are typical problems and are indicators only and are not intended to be a diagnoses. If you suspect you have any kind of problem with yourengine have it inspected by a professional.

Tune-Up Trouble Shooting Ignition Diagnostics By Scope Pattern Fuel Injector Trouble Shooting
Carbon Fouled Plugs Firing Lines Abnormally High Cold Start
Oil Fouled Plugs Firing Lines Abnormally Low Hard Starting
Plug Gap Bridged Several High Firing Lines Rough Idle
Blistered Electrode Several Low Firing Lines Poor Acceleration
Melted Electrode Cylinders Not Firing Poor High Speed Operation
Engine Won't Start Hard Starting Acceleration Ping/Knock
Engine Runs Rough Poor Acceleration Component Failure



Carbon Fouled Plugs
Possible Cause Possible Solution
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
Possible Cause Possible Solution
Worn Rings/Pistons Overhaul/Replace Engine
Excessive Cylinder Wear Overhaul/Replace Engine
Plug Gap Bridged
Possible Cause Possible Solution
Combustion Chamber Carbon Deposits Clean Combustion Chamber



Blistered Electrode
Possible Cause Possible Solution
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
Possible Cause Possible Solution
Incorrect Timing Reset Timing
Burned Valves Replace Valves
Engine Overheating Check Cooling System
Wrong Plug Heat Range Install Correct Plug



Engine Won't Start
Possible Cause Possible Solution
Loose Connections Check Connections
No Power Check Fuses/Battery
Loose/Worn Timing Belt/Chain/Gears Check Belt/Chain/Gears



Engine Runs Rough
Possible Cause Possible Solution
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
Possible Cause Possible Solution
Incorrect Ignition Timing Reset Timing
Leaky Valves Check Compression



Component Failure
Possible Cause Possible Solution
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
Possible Cause Possible Solution
Retarded Ignition Timing Reset Ignition Timing
Lean Air/Fuel Mixture Adjust Fuel Mixture
High Secondary Resistance Repair Secondary Ignition



All Firing Lines Abnormally Low
Possible Cause Possible Solution
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
Possible Cause Possible Solution
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
Possible Cause Possible Solution
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
Possible Cause Possible Solution
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
Possible Cause Possible Solution
Defective Ignition Coil(s) Replace Coil(s)
Fouled Spark Plugs Replace Plugs
Incorrect Timing Reset Ignition Timing



FUEL INJECTION TROUBLE SHOOTING (Cold Start)
Possible Cause Possible Solution
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
Possible Cause Possible Solution
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
Possible Cause Possible Solution
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
Possible Cause Possible Solution
Weak Fuel Pump Replace Fuel Pump
Dirty Fuel Injectors Clean/Replace Injectors
Excessive Intake Valve Deposits Clean Intake System



Poor High Speed Operation
Possible Cause Possible Solution
Low Fuel Pump Volume Faulty Fuel Pump/Filter
Poor MAP Sensor Signal Test Speed Sensor/Circuit



Acceleration Ping/Knock
Possible Cause Possible Solution
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