Lexus ES: Rough Idling

• 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) / Target Fuel Pressure 2
• Fuel Pressure (High)
• Fuel Pressure (Low) / Fuel Pressure 2
• 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 B1S2
• Total FT Bank 1
• Fuel System Status 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 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
• 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
• Compression Leakage Count
• Rough Idle Status
• Plural Cylinders Rough Idle
• Rough Idle Cylinder #1
• Rough Idle Cylinder #2
• Rough Idle Cylinder #3
• Rough Idle Cylinder #4

• Rough Idle Count (Plural Cylinders)
• Rough Idle Count (Compression Leakage)
• Rough Idle Count (Engine Speed Low)
• Rough Idle Count (Low Frequency)
• Rough Idle Count #1
• Rough Idle Count #2
• Rough Idle Count #3
• Rough Idle Count #4

HINT:

• If any other DTCs are output, perform troubleshooting for those DTCs first.
• Make sure to reproduce the conditions present when the malfunction occurred.
• Using the Techstream, read the Data List to confirm the engine operating conditions. This information can be useful when troubleshooting.
• The vehicle condition when the problem symptoms occurred can be determined using the Vehicle Control History.
• As the Vehicle Control History data may be overwritten whenever the trigger conditions are met, make sure to save the Vehicle Control History data before performing any inspections.
• If the problem symptoms do not recur, attempt to reproduce the symptoms and conditions when the malfunction occurred based on the result of the customer problem analysis and Vehicle Control History. Place the priority on confirming the symptoms.
• When performing inspections, jiggle the relevant wire harnesses and connectors in an attempt to reproduce malfunctions that do not always occur.
• The suspected cause of the problem symptoms can be determined using the codes, items, and Freeze Frame Data within the Vehicle Control History.
• When confirming the Freeze Frame Data, be sure to check all multi Freeze Frame Data.
• When confirming the Freeze Frame Data, if there are multiple items related to the cause of the malfunction, perform troubleshooting for all related items.
• If the malfunction is currently occurring, use the Data List to confirm the current vehicle condition. By using the Data List, more detailed vehicle information can be confirmed than by using Vehicle Control History Freeze Frame Data by itself.
• As Vehicle Control History may be stored when performing an Active Test, learning, etc., make sure to clear the Vehicle Control History before returning the vehicle to the customer.

HINT:

• The vehicle condition when the problem symptoms occurred can be determined by confirming the Vehicle Control History Freeze Frame Data.
• As the Vehicle Control History data may be overwritten whenever the trigger conditions are met, make sure to save the Vehicle Control History data before performing any inspections.
• Using information from the customer about when the problem symptom occurred, find the Freeze Frame Data with the appropriate Key Cycle, Total Distance Traveled, etc., to find vehicle history that may be related to the problem symptoms.

HINT:

• By using snapshot to store the Data List, the Data List items can be compared to the Vehicle Control History.
• If the problem symptoms cannot be reproduced, refer to Check for Intermittent Problems, and try to reproduce the conditions when the problem symptoms occurred as stated by the customer. If the problem symptoms still cannot be reproduced, perform the following procedure.

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HINT:

• If the malfunction is currently occurring, compare the values of the Data List items with the vehicle control history Freeze Frame Data.
• If the malfunction is not currently occurring, read the Vehicle Control History Freeze Frame Data.

HINT:

• "Total FT Bank 1" is used to detect an abnormal air fuel ratio. As the value of "Total FT Bank 1" is corrected by the ECM before it is displayed in the Data List, the displayed value may not be equal to the sum of the measured "Short FT B1S1" and "Long FT B1S1".
• An abnormally lean or rich tendency can be checked by reading the following Data List items: 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 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 and A/F Learn Value High Bank.
• The following may cause a lean air fuel ratio (an operating range in which the air fuel ratio learned value correction is +20% or more):
  1. Decrease in fuel injector assembly injection volume
  2. Decrease in mass air flow meter sub-assembly output (due to existence of foreign matter)
  3. Air leaks in intake system after mass air flow meter sub-assembly
  4. Decrease in fuel pressure (at fuel filter, fuel pump, fuel main valve assembly or fuel suction plate sub-assembly)
• On vehicles which the learning value for each operating range can be checked, if the value of "A/F Learn Value High (Port) Bank 1" or "A/F Learn Value High Bank 1" only is corrected to the positive side, a malfunction in the fuel system (clogging of the fuel pump or fuel filter) is suspected.
• On vehicles which the learning value for each operating range can be checked, if the value of "A/F Learn Value Idle (Port) Bank 1", "A/F Learn Value Low (Port) Bank 1", "A/F Learn Value Idle Bank 1" or "A/F Learn Value Low Bank 1" only is corrected to the positive side, an air leak after the mass air flow meter sub-assembly is suspected.
• The following may cause a rich air fuel ratio (an operating range in which the air fuel ratio learned value correction is -20% or less):
  1. Increase in the fuel injector assembly injection volume
  2. Purge VSV system

HINT:

• Perform fuel-cut of port injection and direct injection for each cylinder and check the change in the engine speed.
• If the engine speed of a cylinder does not change while performing the Active Test, it can be determined that the cylinder is malfunctioning.
• If the engine speed of all cylinders change while performing the Active Test, it can be determined that multiple cylinders are malfunctioning.
• A cylinder for which the Data List item "Misfire Count Cylinder #1 to #4" increases may be malfunctioning.
• If "Compression Leakage Count" in the Data List increases, misfiring due to insufficient compression may be occurring.

NOTICE:

• Do not crank the engine continuously for 20 seconds or more.
• If it is necessary to crank the engine again after Check the Cylinder Compression has been changed to "Start" and the engine has been cranked once, press Exit to return to the Active Test menu screen. Then change Check the Cylinder Compression to "Start" and crank the engine.
• Make sure the battery is fully charged before performing this Active Test.

HINT:

• At first, the Techstream will display extremely high cylinder engine speed values. After approximately 10 seconds of engine cranking, the engine speed measurement of each cylinder will change to the actual engine speed.
• If the cylinder engine speed values (Engine Speed Cylinder #1 to #4) displayed in the Data List do not change from an extremely high value, return to the Active Test menu screen, change "Check the Cylinder Compression" to "Start" and crank the engine again within 1 second.

NOTICE:

• If the Active Test is changed to "Stop" while the engine is being cranked, the engine will start.
• When performing the Active Test, Vehicle Control History code X0810 (Engine Difficult to Start (Engine Starting Time Long)) may be stored.
• After performing the Active Test, make sure to check and clear DTCs.

HINT:

• If the value of Data List item "Engine Speed Cylinder" of a cylinder is higher than other cylinders, the cylinder may be malfunctioning.
• If the value of Data List item "Engine Speed Cylinder" is high for only one cylinder, compression loss is suspected.

HINT:

• Increase and decrease the fuel injection volume of the port injection and direct injection simultaneously and check the vehicle condition.
• Change the fuel injection volume between the minimum and maximum range of correction (e.g. -12.5% to 24.8%).

HINT:

• Interchange the ignition coil assembly and spark plug of the malfunctioning cylinder with those of a known good cylinder and check if the malfunctioning cylinder returns to normal.
• If the spark plug of the malfunctioning cylinder is abnormally wet with fuel even after the ignition coil assembly and spark plug are replaced, a leaking fuel injector assembly is suspected.

HINT:

• If the air fuel ratio learned value is corrected to the positive side for all operating ranges due to low fuel injector assembly injection volume, replace the fuel injector assemblies of all cylinders.
• Perform "Inspection After Repair" after replacing the fuel injector assembly.

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NOTICE:

• Do not leave the EGR valve open for 10 seconds or more during the Active Test.
• Be sure to return the EGR valve to step 0 when the Active Test is completed.
• Do not open the EGR valve 30 steps or more during the Active Test.

NOTICE:

• The air fuel ratio sensor (sensor 1) has an output delay of a few seconds and the air fuel ratio sensor (sensor 2) has a maximum output delay of approximately 20 seconds.
• Read the output current immediately after warming up the air fuel ratio sensors to avoid an inaccurate reading due to a sensor cooling.

HINT:

• Increase and decrease the fuel injection volume of the port injection and direct injection simultaneously and check the vehicle condition.
• Change the fuel injection volume between -12 to 12%.

• Engine mount deterioration
• Deposits in the intake manifold or on an intake valve
• Delay in fuel supply due to adherence of the fuel to the deposits

HINT:

• If there is foreign matter in the intake system components, remove it before proceeding to the next step.
• If there is no foreign matter in the intake system components, check for foreign matter in the mass air flow meter sub-assembly. If there is foreign matter in the mass air flow meter sub-assembly, remove it.

NOTICE:

• Make sure that the cloth or your fingers do not get caught in the valve.
• Make sure that foreign matter does not enter the throttle valve.
• Do not directly apply non-residue solvent to the throttle body with motor assembly or wash the throttle body with motor assembly. Cleaning solvent may leak into the motor from the shaft and cause problems such as rust or valve movement problems.
• If there is coating material on the edge of the valve, be careful not to remove it.

 Throttle Body

 On-vehicle Inspection

 Removal

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