The engine idling speed is not constant. The engine or vehicle may shake in severe situations. The engine idling speed may vary. Any of these conditions can be severe enough to cause the engine to stall.
Perform the Diagnostic system check - engine controls.
Perform the Fuel supply pump functional inspection.
Remove the air cleaner and inspect for contamination, collapsing in the air duct, or any condition that restricts the flow.
Ensure that the ground of the ECM is free of dirt and is fixed securely in the correct position.
Inspect whether the harness connector is properly connected.
Inspect the fuel type and quality.
Verify the injector ID code of each cylinder.
Check the scan tool data list.
Check for related Service Bulletins.
Compare the Engine Coolant Temperature (ECT), Intake Air Temperature (IAT), and Fuel Temperature parameters while the engine is cold. If the difference between the temperature values is 5°C {9°F} or more when the engine is cold, inspect for high resistance in each circuit and for a sensor malfunction.
{When the ignition switch is turned ON, the MAF sensor is heated, and as a result, the IAT shows a higher value than the normal intake air temperature.}
Observe the Fuel Rail Pressure (FRP) Sensor parameter on the scan tool. It is normal if the Fuel Rail Pressure (FRP) Sensor parameter shows approximately 20 MPa or more when the ignition switch is turned ON without starting the engine after the engine operation is stopped. If not, inspect for high resistance in each circuit and for a sensor malfunction.
When idling the engine in neutral, observe the Fuel Rail Pressure (FRP) parameter. It is normal if the value is always in the range of 27 to 33 MPa {3,900 to 4,800 psi} after the engine is warmed up.
The CKP sensor is securely installed, and the sensor rotor is not damaged.
The CMP sensor is securely installed, and the timing chain sprocket is not damaged.
Inspect for air in the fuel system.
Inspect for water in the fuel.
Inspect the fuel for being frozen.
Inspect whether the fuel filter warning light illuminates intermittently or frequently.
Inspect the fuel filter for clogging.
Inspect for external fuel leakage and excessive engine oil.
Inspect for fuel leakage from the injector.
Inspect for collapsing, twisting, improper tightening, cracking, or clogging in the fuel system between the fuel tank and the fuel supply pump.
Inspect the vent valve and hose of the fuel tank for clogging.
{The piping may be clogged due to foreign material from the fuel tank entering the fuel system.}
Inspect the operation of the fuel supply pump.
{The fuel supply pump must be timed with the engine, and the adjusted value should be learned by the ECM.}
Perform the Injector Cutoff with a scan tool.
Inspect the air cleaner, air intake duct, and intercooler for clogging, holes, or leakage.
Inspect for any condition that restricts flow within the turbocharger intake duct.
Inspect for a stuck intake throttle valve.
Inspect for clogging or leakage in the inlet manifold.
Inspect whether the exhaust system flow is restricted.
Inspect the compression pressure of the engine.
Inspect for poor timing of the idle gear and timing chain.
Inspect the valve clearance.
Inspect the valve spring for breakage and fatigue.
Inspect the camshaft for wear.
Inspect the basic components of the engine including the camshaft, the cylinder head, and the pistons.
EMI may cause engine failure.
The scan tool can usually detect EMI by checking the engine speed. EMI occurs when rotation speed sharply increases even when the actual engine speed hardly changes. If any problem is found, inspect whether any high-voltage component such as injector wiring is connected to the area around the sensor circuit.
Inspect the engine mounting for abnormal conditions.
Inspect the crank pulley for a malfunction.
Inspect the generator or A/C compressor.
Inspect the generator output voltage.
Inspect the EGR system operation.
Perform the EGR control system check.
Inspect the operation of the A/C.