Preliminary Checks
On A/T models, ensure gearshift lever is in Park. On M/T models, ensure clutch is fully depressed. Check battery connections. Check starter relay connections. Check alarm/anti-theft devices. Check fuses and fusible links. Check ignition switch.
Check for engine overheating. Check all wiring harness connectors. Check engine oil level and quality. Check Manifold Absolute Pressure (MAP) sensor hose. Check transmission Torque Converter Clutch (TCC) solenoid.
Check engine oil level. Ensure proper engine oil dipstick is being used. Check fuel quality. Check air restriction gauge located on air filter housing to determine if air cleaner needs replacement.
Check for binding or stuck accelerator pedal. Check for broken accelerator return spring.
Check engine oil level. Check for proper engine oil dipstick. Check for proper oil viscosity. Check if engine oil has been changed within 5000 miles. Check fuel quality. Check for intake manifold leaks. Check MAP sensor hose.
Check for binding or stuck accelerator pedal. Check for damaged accelerator return spring. Check if engine is operating at normal operating temperature.
RUNS ROUGH, MISSES, BUCK/JERK, HESITATION OR STUMBLES
Note. The Powertrain Control Module (PCM) is equipped with an over RPM/speed limiting function that will shut off fuel delivery when predetermined speed is exceeded.
Check for engine overheating. Check wiring harness connectors for corroded, loose or damaged terminals. Check engine oil level and quality. Check Manifold Absolute Pressure (MAP) sensor hose. On A/T models, check fluid level.
SURGE (ON ACCELERATION OR CRUISE)
Note. The Powertrain Control Module (PCM) is equipped with an over RPM/speed limiting function that will shut off fuel delivery when predetermined speed is exceeded.
Check engine oil level and quality. Check wiring harness connectors for corroded, loose or damaged terminals.
LOSS OF POWER/POOR FUEL ECONOMY
Note. The PCM is equipped with an RPM/speed limiting function that will shut off fuel delivery when predetermined speed is exceeded.
Verify symptom occurs under normal driving conditions without engine being under excessive load conditions. Check for binding/dragging brakes. Check wiring harness connectors. Check transmission fluid. Check engine oil level. Check for proper engine oil dipstick. Check for proper oil viscosity. Check fuel quality.
Perform the following
- Check Manifold Absolute Pressure (MAP) sensor hose for leaks.
- Check air restriction gauge, located on air filter housing, to determine if air cleaner needs replacement.
- Check for correct MAP sensor.
- Check intake manifold for leaks.
- Check fuel quality.
- With ignition on, check PID values for EBP, MAP and BARO sensors. All readings should be within one psi (7 kPa) of each other. If any reading is not within one psi (7 kPa), perform appropriate circuit test for sensor value that disagrees with other sensor value readings. See «TESTS W/CODES - 7.3L DIESEL»(ref-24260) article.
White Smoke (Water In Combustion)
Perform the following
- Check glow plug system operation.
- Check engine mechanical condition. Check for cylinder head and intake manifold gasket leaks. Check for cracked/porous cylinder head and engine block.
- Perform ENGINE PERFORMANCE DIAGNOSIS in «SYSTEM/COMPONENT TESTS - 7.3L DIESEL»(ref-24265) article.
Black Smoke
Perform the following
- Apply vacuum to MAP sensor. If MAP sensor does not hold vacuum, replace MAP sensor.
Preliminary Check
Check transmission fluid level and condition.
Check for external engine oil leaks. Check for proper oil dipstick. Check for proper oil viscosity.
Intermittent Simulation
To reproduce the 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. See TESTS W/CODES - 7.3L DIESEL article. Use test results to identify a faulty component or circuit.