Lack of Power [11/2018 - 10/2019]: Description

HINT: 

The following are descriptions of the characteristics of each system malfunction. After understanding the link between the causes and symptoms, perform the inspection of each component. Even if the problem symptom does not recur, signs of the malfunction may be found in the Data List.

1. Ignition system
   SPARK PLUG
   
   

   Main cause of malfunction	Performance degradation (wear, existence of foreign matter, etc.)
   Symptom	Engine speed fluctuation due to abnormal combustion
   Data List	Misfire Count Cylinder #1 to #4
   HINT:  If the spark plug of the malfunctioning cylinder is abnormally wet with fuel, a leaking fuel injector assembly is suspected.

   IGNITION COIL ASSEMBLY
   
   

   Main cause of malfunction	Internal malfunction
   Problem symptom	Engine speed fluctuation due to abnormal combustion
   Data List	Misfire Count Cylinder #1 to #4

2. Fuel system
   FUEL INJECTOR ASSEMBLY
   
   

   Main cause of malfunction	Blockage
   Problem symptom	Engine speed fluctuation due to abnormal combustion Idle speed too low or high
   Data List	Target Air-Fuel Ratio Short FT B1S1 Long FT B1S1 Total FT Bank 1 Fuel System Status Bank 1 A/F Learn Value Idle Bank 1 A/F Learn Value Low Bank 1 A/F Learn Value Mid No. 1 Bank 1 A/F Learn Value Mid No. 2 Bank 1 A/F Learn Value High Bank 1 A/F Learn Value Idle (Port) Bank 1 A/F Learn Value Low (Port) Bank 1 A/F Learn Value Mid No. 1 (Port) Bank 1 A/F Learn Value Mid No. 2 (Port) Bank 1 A/F Learn Value High (Port) Bank 1 A/F Learn Value Low (Dual) Bank 1 A/F Learn Value Mid (Dual) No. 1 Bank 1 A/F Learn Value Mid (Dual) No. 2 Bank 1 A/F Learn Value High (Dual) Bank 1
   HINT:  If the engine malfunction disappears when the fuel injection volume is increased or decreased using the Control the Injection Volume, the respective cylinder may be malfunctioning.

   FUEL SYSTEM
   
   

   HINT:  If the air fuel ratio becomes lean only when the engine is running under a high load and at a high engine speed, clogging of the fuel pump or fuel filter is suspected.

   FUEL QUALITY
   
   

   Main cause of malfunction	Fuel degradation due to age or water contamination Low fuel quality Addition of fuel additive
   Problem symptom	Engine speed fluctuation due to abnormal combustion Idle speed too low or high Engine is difficult to start

3. Intake and exhaust systems
   EGR SYSTEM
   
   

   Main cause of malfunction	Improper operation, sticking
   Problem symptom	Engine speed fluctuation due to abnormal combustion Idle speed too low or high Engine is difficult to start, lacks power or stalls
   Data List	Target EGR Valve Position No. 1 EGR Step Position Normal condition: Actual EGR valve position = Target EGR valve position +/-5% (Fully closed: 0%, Fully open: 100%) Perform the Active Test "Control the EGR Step Position" and check if the vehicle condition changes when the EGR valve position is changed When the ignition switch is turned to ON (engine not started), the EGR valve is fully closed

   MASS AIR FLOW METER SUB-ASSEMBLY
   
   

   Main cause of malfunction	Performance degradation (existence of foreign matter, etc.)
   Problem symptom	Lack of power
   Data List	Mass Air Flow Sensor
   HINT:  If the value of the Data List item "Mass Air Flow Sensor" is abnormal, a malfunction of the mass air flow meter sub-assembly is suspected.

   THROTTLE SYSTEM
   
   

   Main cause of malfunction	Inappropriate trim volume adjustment due to accumulation of deposits
   Problem symptom	Engine speed fluctuation due to abnormal combustion Idle speed too low or high Lack of power
   Data List	Engine Stall Control F/B Flow ISC F/B Learn Torque ISC Total AUXS Torque ISC F/B Torque Sum of ISC F/B Torque (Recent) ISC AUXS Torque (Alternator) ISC AUXS Torque (Air Conditioner) Throttle Air Flow F/B Value

   AIR FUEL RATIO SENSOR (SENSOR 1), AIR FUEL RATIO SENSOR (SENSOR 2)
   
   

   Main cause of malfunction	Deviation in sensor characteristics
   Problem symptom	Abnormal combustion due to deviation of actual air fuel ratio from calculated ratio
   Data List	A/F (O2) Sensor Current B1S1 A/F (O2) Sensor Current B1S2 Fuel System Status Bank 1

4. Engine
   ENGINE ASSEMBLY
   
   

   Main cause of malfunction	Compression loss Accumulation of deposits (Combustion chamber, intake valve or intake manifold)
   Problem symptom	Engine speed fluctuation due to abnormal combustion Idle speed too low or high Hesitation during acceleration or stalling
   HINT:  If deposits have accumulated in the combustion chamber or on an intake valve, the engine may stall when deposits are caught on an intake valve. When performing the Active Test "Check the Cylinder Compression", if the speed of one cylinder is higher than the others, the cylinder may have a compression loss. If deposits accumulate on the intake valves, the supply of fuel may be delayed due to adherence of the fuel to the deposits, causing a rough idle.

HINT: 

Depending on the vehicle model, the applicable Data List items may vary. Data List items other than the ones used in the diagnostic procedure are for reference only.

• Mass Air Flow Sensor
• Engine Stall Control F/B Flow
• ISC F/B Learn Torque
• ISC Total AUXS Torque
• ISC F/B Torque
• Sum of ISC F/B Torque (Recent)
• ISC AUXS Torque (Alternator)
• ISC AUXS Torque (Air Conditioner)
• Throttle Air Flow F/B Value
• Target Fuel Pressure (High)
• Target Fuel Pressure (Low)
• Fuel Pressure (High)
• Fuel Pressure (Low)
• High Pressure Fuel Pump Duty Ratio (D4)
• High Pressure Fuel Pump Discharge Rate
• Target Air-Fuel Ratio
• A/F (O2) Sensor Current B1S1
• A/F (O2) Sensor Current B1S2
• Short FT B1S1
• Long FT B1S1
• Total FT Bank 1
• Fuel System Status Bank 1
• A/F Learn Value Idle Bank 1
• A/F Learn Value Low Bank 1
• A/F Learn Value Mid No. 1 Bank 1
• A/F Learn Value Mid No. 2 Bank 1
• A/F Learn Value High Bank 1
• A/F Learn Value Idle (Port) Bank 1
• A/F Learn Value Low (Port) Bank 1
• A/F Learn Value Mid No. 1 (Port) Bank 1
• A/F Learn Value Mid No. 2 (Port) Bank 1
• A/F Learn Value High (Port) Bank 1
• A/F Learn Value Low (Dual) Bank 1
• A/F Learn Value Mid (Dual) No. 1 Bank 1
• A/F Learn Value Mid (Dual) No. 2 Bank 1
• A/F Learn Value High (Dual) Bank 1
• Target EGR Valve Position No. 1
• EGR Step Position
• Misfire Count Cylinder #1
• Misfire Count Cylinder #2
• Misfire Count Cylinder #3
• Misfire Count Cylinder #4

HINT: 

The frequency of the malfunction can be determined by confirming the number of times the symptom occurred.

• Engine Lack of Power Count