Additional Symptoms Tests

Hard Start

• Verify that the ECT has not shifted in value. Refer to Temperature Versus Resistance (Fuel Temperature Sensor) or Temperature Versus Resistance (ECT Sensors) or Temperature Versus Resistance (IAT Sensor 1) or Temperature Versus Resistance (IAT Sensor 2) or Temperature Versus Resistance (EGT Sensors) or Temperature Versus Resistance (EGR Temperature Sensors) .
• Inspect for a slow cranking speed. Refer to Symptoms - Engine Electrical .
• Verify the engine electrical system for correct operation. Refer to Symptoms - Engine Electrical .
• Verify that the driver is using the correct starting procedure as described in the owners manual.
• Inspect for a restriction in turbocharger inlet duct.
• Inspect for a restriction or a leak in the intake manifolds.
• Inspect the exhaust system for a possible restriction. Refer to Restricted Exhaust .
• Inspect for excessive crankshaft endplay that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor.

Hesitation, Sag, Stumble

• Test the generator. Refer to Symptoms - Engine Electrical . Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.
• Inspect for excessive crankshaft endplay that will cause the CKP sensor reluctor wheel to move out of alignment with the CKP sensor.

Poor Fuel Economy

• Suggest to the driver to read the Important Facts on Fuel Economy in the Owner Manual.
• Confirm proper interpretation of the Average Fuel Economy value on the DIC. The Fuel Economy value should be reset periodically. Particularly if driving patterns, including load, terrain, etc., have changed significantly since the last Fuel Economy Reset.
• Suggest to the owner to fill the fuel tank and inspect the fuel economy.
• The following conditions can reduce fuel economy:
  • Aftermarket body accessories that can affect wind flow over the vehicle. Including air deflectors, flares, etc.
  • Heavy loads being carried or towed, or the shape of large loads
  • Extended idle time
  • Acceleration rate too much or too often
  • Incorrect tire size or air pressure
  • Improper fuel quality and rating-Refer to Contaminants-in-Fuel Diagnosis  and Fuel System Specifications .
  • Aftermarket ECM calibrations
  • Certain aftermarket air filters or air induction systems
  • An air leak in the induction or engine systems-Refer to full system air leak test in Charge Air Cooler Diagnosis (Induction System Smoke Test)  or Charge Air Cooler Diagnosis (Full System Air Leak Test) .
  • Fuel system issues-Inspect the injector balance rates. Balance rates should be between +4 mm³ and -6.9 mm³ in Park or Neutral.
  • Brake system drag
  • Air conditioning system improper operation
  • Incorrect operation of the speedometer

Lack of Power, Hesitation, or Cut Out

• Inspect the engine electrical system for correct operation. Refer to Symptoms - Engine Electrical .
• Inspect for auxiliary fuel filters. Refer to Fuel Injection Line Routing Diagram for proper fuel filter locations. Aftermarket fuel filters may restrict fuel flow.
• Compare the vehicle with a similar unit. Ensure the vehicle has an actual problem.
• Inspect for a proper transmission operation.
• Inspect the engine oil level and quality.
• Inspect for an air leak in the charge air cooler. Refer to Charge Air Cooler Diagnosis (Induction System Smoke Test)  or Charge Air Cooler Diagnosis (Full System Air Leak Test) .
• Inspect for a worn or damaged turbo charger turbine wheel, shaft or compressor wheel.
• Inspect for a restriction in the charge air cooler.
• Inspect for a skewed mass air flow (MAF) sensor. Refer to Diagnostic Aids in DTC P0101 .
• Inspect that the exhaust gas recirculation (EGR) valve is fully closing. Remove the EGR valve and visually inspect that there is no light seen between the valves and the valve seats.
• Ensure that the EGR valve does not bind when manually moving the valve.
• Inspect the torque converter clutch (TCC) operation.
• Inspect the air conditioning system for proper operation. Refer to Air Conditioning (A/C) System Performance Test (Diesel Engine) or Air Conditioning (A/C) System Performance Test (Gas Engine w/ Electric Cooling Fan) or Air Conditioning (A/C) System Performance Test (Gas Engine w/Engine Driven Fan) or Air Conditioning (A/C) System Performance Test (HP2) .
• Inspect the exhaust system for a possible restriction.

Rough, Unstable, or Incorrect Idle and Stalling

• Inspect the engine mounts. Refer to Engine Mount Inspection .
• Inspect the intake and exhaust manifolds for casting flash.
• The exhaust system for damaged or collapsed pipes
• The exhaust manifold for a collapsed inner wall
• The mufflers for heat distress or possible internal failure
• EMI on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM, with little change in actual engine RPM change, indicates that EMI is present. If a problem exists, inspect routing of high voltage components, such as fuel injector wiring, near the sensor circuits.
• Inspect the park neutral position (PNP) switch circuit.

Surges/Chuggles

• Ensure the driver understands the torque converter clutch (TCC) operation.
• Ensure the driver understands the A/C compressor operation.
• Use the scan tool to ensure the vehicle speed sensor (VSS) reading matches the speedometer. This excludes vehicles with electronic transmissions where some variation between VSS and the speedometer is normal.

Fuel Knock/Combustion Noise

• Inspect for obvious overheating problems. Refer to Engine Overheating .
• Inspect for a low engine coolant level.
• Inspect for any restricted air flow through the radiator. Refer to Radiator Cleaning .
• Inspect for a malfunctioning or incorrect thermostat.
• Inspect for a correct coolant solution. The solution should be a 50/50 mix of anti-freeze and water.

Excessive Smoke (Black)

• The DPF is damaged and must be replaced. Inspect the following possible causes that may have damaged the DPF.
• Inspect for an air leak in the charge air cooler or the air ducts between the turbocharger and the intake manifold. Refer to Charge Air Cooler Diagnosis (Induction System Smoke Test)  or Charge Air Cooler Diagnosis (Full System Air Leak Test) .
• Inspect for a restriction in the turbocharger charge air cooler.
• Inspect for a restriction in the intake manifold.
• Inspect for excessive oil entering the combustion chamber. Refer to Oil Consumption Diagnosis .
• Inspect for a stuck open EGR valve.
IMPORTANT: Do NOT drain the coolant at this time.
• Remove the air inlet tube to the intake manifold. Refer to Exhaust Gas Recirculation Valve Cooler Replacement . Perform steps 1-15.
• Visually inspect the EGR valve and verify the valve is in the closed position.
• Ensure that the EGR valve does not bind when manually moving the valve.

Excessive Smoke (White)

• Check the coolant level in the reservoir. White coolant smoke may be mistaken for blue/gray smoke. If the coolant level is low, refer to Loss of Coolant .
• If excessive smoke is present, inspect for a stuck open fuel injector by performing the following procedure:
  1. Disconnect the CKP sensor.
  2. Remove the glow plugs. Refer to Glow Plug Replacement - Bank 1 and Glow Plug Replacement - Bank 2 .
  IMPORTANT: Do not stand in front of the glow plug holes while cranking the engine.
  3. Crank the engine while observing the glow plug holes for fuel spray.
  4. Replace the fuel injectors for the cylinders that spray fuel.
  5. Inspect for contaminated oil or high oil level.
• If the ECM glow plug control module (GPCM) or a fuel injector has recently been replaced, it may be necessary to confirm the fuel injector flow rate values. Refer to Fuel Injector Flow Rate Programming .
• Inspect the fuel injectors. Refer to Fuel Injector Balance Test with Tech 2 .

Excessive Smoke (Blue, Gray, or White) 

Blue, gray, or white smoke during regeneration may indicate a fuel with high sulfur content.