A/C DOES NOT TURN OFF DURING WIDE OPEN THROTTLE (WOT)
- Check for Throttle Position (TP) sensor circuit malfunction.
- Check for loose TP sensor.
EMISSIONS FAILURE
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for worn engine parts.
- Check for malfunctioning cooling system.
- Check for restricted air filter.
- Check for intake system vacuum leak.
- Check for throttle body malfunction.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for restricted fuel filter or fuel intake sock.
- Check for Camshaft Position (CMP) sensor malfunction.
- Check for damaged camshaft.
- Check for incorrect air/fuel mixture ratio.
- Check for restricted exhaust system.
- Check for catalytic converter malfunction.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
ENGINE RUNS ROUGH, MISSES, HESITATES, STUMBLES, SURGES OR STALLS DURING ACCELERATION OR CRUISE, OR ENGINE BUCKS OR JERKS DURING ACCELERATION, CRUISE OR DECELERATION
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for poor fuel quality.
- Check for overheating engine.
- Check for restricted air filter.
- Check for intake system vacuum leak.
- Check for throttle body malfunction.
- Check for spark plug malfunction.
- Check for Crankshaft Position (CKP) sensor malfunction.
- Check for damaged crankshaft pulley.
- Check for incorrect gap between CKP sensor and crankshaft pulley.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for fuel injector malfunction.
- Check for restricted fuel filter or fuel intake sock.
- Check for Camshaft Position (CMP) sensor malfunction.
- Check for damaged camshaft.
- Check for incorrect air/fuel mixture ratio.
- Check for restricted exhaust system.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
- Check reference voltage circuit malfunction.
- Check for main relay malfunction.
- Check for Mass Air Flow (MAF) sensor circuit malfunction.
- Check for Throttle Position (TP) sensor circuit malfunction.
- Check TP sensor for looseness and misadjustment.
- Check for incorrect A/C refrigerant charging amount.
- Check for malfunctioning A/C relay circuit.
- Check for malfunctioning condenser fan circuit.
- Check for slipping clutch (M/T).
- Check for A/T malfunction.
- Check for Vehicle Speed Sensor (VSS) circuit malfunction.
ENGINE STALLS AT IDLE OR JUST AFTER STARTING
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for hydrostaticaly-locked engine.
- Check for poor fuel quality.
- Check for overheating engine.
- Check for restricted air filter.
- Check for intake system vacuum leak.
- Check for Idle Air Control (IAC) valve malfunction.
- Check for ignition coil malfunction.
- Check for incorrect ignition timing do to Crankshaft Position (CKP) sensor malfunction or damaged crankshaft pulley.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for Crankshaft Position (CKP) sensor malfunction.
- Check for damaged crankshaft pulley.
- Check for incorrect gap between CKP sensor and crankshaft pulley.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for fuel injector malfunction.
- Check for fuel system fuel leaks.
- Check for incorrect air/fuel mixture ratio.
- Check for restricted exhaust system.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
- Check for malfunctioning main relay.
- Check for incorrect A/C refrigerant charging amount.
- Check for malfunctioning A/C relay circuit.
- Check for malfunctioning condenser fan circuit.
EXCESSIVE OIL CONSUMPTION
- Check for incorrect engine oil viscosity.
- Check for wrong dipstick.
- Check for restricted PCV system.
- Check for worn engine parts.
EXHAUST SMOKE
- Check for worn engine parts.
- Check for cooling system malfunction.
- Check for restricted air filter.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for fuel injector malfunction.
- Check for Pressure Regulator Control (PRC) solenoid valve malfunction.
- Check for restricted PCV system.
FUEL ODER IN ENGINE COMPARTMENT
- Check for fuel pressure regulator malfunction.
- Check for fuel system leaks.
- Check for Evaporative emission control system malfunction.
HART TO START (LONG CRANKING, ERRATIC CRANKING OR ERRATIC STARTING)
- Check for poor fuel quality.
- Check for restricted air filter.
- Check for intake system vacuum leak.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for Crankshaft Position (CKP) sensor malfunction.
- Check for damaged crankshaft pulley.
- Check for incorrect gap between CKP sensor and crankshaft pulley.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for restricted fuel filter or fuel inlet sock.
- Check for pressure regulator control solenoid valve malfunction.
- Check for incorrect air/fuel mixture ratio.
- Check for restricted exhaust system.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
- Check for MAF sensor circuit malfunction.
HIGH IDLE OR RUN-ON
- Check throttle cable adjustment.
- Check Engine Coolant Temperature (ECT) sensor malfunction.
- Check for incorrect load signal input.
KNOCKING OR PINGING DURING ACCELERATION OR CRUISE
- Check for incorrect engine compression.
- Check for malfunctioning cooling system.
- Check for overheating engine.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for MAF sensor circuit malfunction.
LACK OR LOSS OF POWER DURING ACCELERATION OR CRUISE
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for poor fuel quality.
- Check for overheating engine.
- Check for restricted air filter.
- Check for intake system vacuum leak.
- Check for throttle body malfunction.
- Check for tumble swirl control system malfunction.
- Check for spark plug malfunction.
- Check for Crankshaft Position (CKP) sensor malfunction.
- Check for damaged crankshaft pulley.
- Check for incorrect gap between CKP sensor and crankshaft pulley.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for fuel injector malfunction.
- Check for Camshaft Position (CMP) sensor malfunction.
- Check for damaged camshaft.
- Check for restricted exhaust system.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
- Check for incorrect A/C refrigerant charging amount.
- Check for malfunctioning A/C relay circuit.
- Check for malfunctioning condenser fan circuit.
- Check for slipping clutch (M/T).
- Check for A/T malfunction.
- Check for Vehicle Speed Sensor (VSS) circuit malfunction.
- Check for dragging brakes.
LOW IDLE OR ENGINE STALLS DURING DECELERATION
- Check for intake system vacuum leak.
- Check for Idle Air Control (IAC) valve malfunction.
- Check for incorrect air/fuel mixture ratio.
- Check for evaporative emission control system malfunction.
- Check for brake switch circuit malfunction.
- Check for neutral switch (M/T) or clutch switch (M/T) circuit malfunction.
- Check for Mass Air Flow (MAF) sensor circuit malfunction.
- Check for Throttle Position (TP) sensor circuit malfunction.
- Check TP sensor for looseness and misadjustment.
- Check for A/C relay circuit malfunction.
NO CRANK
- Check for starter malfunction.
- Check for open starter or ignition switch circuit.
- Check for low battery charge.
- Check for charging system malfunction.
- Check for hydrostaticaly-locked engine.
- Check for seized drive plate (A/T) or flywheel (M/T).
- Ensure transmission is in Park (A/T) or neutral (M/T). Ensure clutch is fully depressed (M/T).
NO START (CRANKS NORMALLY)
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for hydrostaticaly-locked engine.
- Check for poor fuel quality.
- Check for overheating engine.
- Check for intake system vacuum leak.
- Check for Idle Air Control (IAC) valve malfunction.
- Check for ignition coil malfunction.
- Check for incorrect ignition timing do to Crankshaft Position (CKP) sensor malfunction or damaged crankshaft pulley.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for Crankshaft Position (CKP) sensor malfunction.
- Check for damaged crankshaft pulley.
- Check for incorrect gap between CKP sensor and crankshaft pulley.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for fuel injector malfunction.
- Check for fuel system fuel leaks.
- Check for incorrect air/fuel mixture ratio.
- Check for restricted exhaust system.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
- Check for reference voltage circuit malfunction.
- Check for main relay malfunction.
POOR FUEL MILEAGE
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for proper engine coolant level.
- Check for malfunctioning cooling system.
- Check for cooling fan system malfunction.
- Check for poor fuel quality.
- Check for restricted air filter.
- Check for tumble swirl control system malfunction.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for restricted fuel filter or fuel intake sock.
- Check for Pressure Regulator Control (PRC) solenoid valve malfunction.
- Check for Camshaft Position (CMP) sensor malfunction.
- Check for damaged camshaft.
- Check for restricted exhaust system.
- Check for PCV valve malfunction.
- Check for condenser fan malfunction.
- Check for incorrect ATF level.
- Check for dragging brakes.
ROUGH OR UNSTABLE IDLE
- Check for incorrect engine compression.
- Check for incorrect valve timing.
- Check for poor fuel quality.
- Check for overheating engine.
- Check for intake system vacuum leak.
- Check for Idle Air Control (IAC) valve malfunction.
- Check for incorrect ignition timing do to Crankshaft Position (CKP) sensor malfunction or damaged crankshaft pulley.
- Check for spark plug malfunction.
- Check for spark plug wire malfunction.
- Check for Crankshaft Position (CKP) sensor malfunction.
- Check for damaged crankshaft pulley.
- Check for incorrect gap between CKP sensor and crankshaft pulley.
- Check for fuel pump malfunction.
- Check for fuel pressure regulator malfunction.
- Check for restricted or plugged fuel lines.
- Check for fuel injector malfunction.
- Check for restricted fuel filter or fuel inlet sock.
- Check for Camshaft Position (CMP) sensor malfunction.
- Check for damaged camshaft.
- Check for incorrect air/fuel mixture ratio.
- Check for restricted exhaust system.
- Check for EGR system malfunction.
- Check for evaporative emission control system malfunction.
- Check for PCV valve malfunction.
- Check for power steering pressure switch circuit malfunction.
- Check for incorrect A/C refrigerant charging amount.
- Check for malfunctioning A/C relay circuit.
- Check for malfunctioning condenser fan circuit.
- Check for incorrect load signal input.
SLOW RETURN TO IDLE
- Check for cooling fan system malfunction.
- Check for throttle body malfunction.
- Check for Engine Coolant Temperature (ECT) sensor malfunction.
- Check for incorrect load signal input.
SULPHUR EXHAUST SMELL
- Check for poor fuel quality.
- Check for evaporative emission control system malfunction.
Intermittent Simulation
To reproduce conditions creating an intermittent fault, use the following methods
- Lightly vibrate component.
- Heat component.
- Wiggle or bend wiring harness.
- Spray component with water.
- Remove/apply vacuum source.
Monitor circuit/component voltage or resistance while simulating intermittent. If engine is running, monitor for self-diagnostic codes. Use test results to identify a faulty component or circuit.