Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Rough Idling

DESCRIPTION

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.
• 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. Place the priority on confirming the symptoms.

SYMPTOM AND CAUSE OF SYSTEM MALFUNCTION

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.

(a) Ignition system

(b) Fuel system

(c) Intake and exhaust systems

(d) Engine

Data List Items Related to Rough Idling

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.

• 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 Cylinder #5
• Rough Idle Cylinder #6
• 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
• Short FT B1S1, B2S1
• Long FT B1S1, B2S1
• Fuel System Status Bank 1, Bank 2
• Target Air-Fuel Ratio
• A/F (O2) Lambda Sensor B1S1, B2S1
• A/F Learn Value Idle (Port) Bank 1, Bank 2
• A/F Learn Value Low (Port) Bank 1, Bank 2
• A/F Learn Value Mid No.1 (Port) Bank 1, Bank 2
• A/F Learn Value Mid No.2 (Port) Bank 1, Bank 2
• A/F Learn Value High (Port) Bank 1, Bank 2
• A/F Learn Value Idle Bank 1, Bank 2
• A/F Learn Value Low Bank 1, Bank 2
• A/F Learn Value Mid No.1 Bank 1, Bank 2
• A/F Learn Value Mid No.2 Bank 1, Bank 2
• A/F Learn Value High Bank 1, Bank 2
• A/F Learn Value Low (Dual) Bank 1, Bank 2
• A/F Learn Value Mid (Dual) No.1 Bank 1, Bank 2
• A/F Learn Value Mid (Dual) No.2 Bank 1, Bank 2
• A/F Learn Value High (Dual) Bank 1, Bank 2
• Total FT Bank 1, Bank 2
• Fuel Pressure (High)
• Fuel Pressure (Low)
• High Pressure Fuel Pump Duty Ratio (D4)
• Target Fuel Pressure (High)
• Target Fuel Pressure (Low)
• High Pressure Fuel Pump Discharge Rate
• Mass Air Flow Sensor
• Misfire Count Cylinder #1 to #6
• A/F (O2) Sensor Voltage B1S1, B2S1
• O2 Sensor Voltage B1S2, B2S2

PROCEDURE

(a) Interview the customer for details about the conditions when the rough idle occurred.

HINT:

Depending on the conditions when the rough idle occurred, a malfunction in one of the following areas is suspected.

NEXT

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Perform a road test.

(e) Enter the following menus: Powertrain / Engine / Trouble Codes.

(f) Read the DTCs.

B

GO TO DTC CHART

A

(a) Check if the problem symptoms reported in the customer problem analysis recur.

HINT:

If the problem symptoms do not recur, attempt to reproduce the conditions when the malfunction occurred based on the result of the customer problem analysis.

B

CHECK FOR INTERMITTENT PROBLEMS

A

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / ISC F/B Learn Torque.

(e) Read the value displayed on the Techstream.

B

GO TO STEP 11

A

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Data List / Short FT B1S1, Short FT B2S1, Long FT B1S1 and Long FT B2S1.

(e) Read the value displayed on the Techstream.

HINT:

• "Total FT Bank 1 (Bank 2)" is used to detect an abnormal air fuel ratio. As the value of "Total FT Bank 1 (Bank 2)" are 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 (B2S1)" and "Long FT B1S1 (B2S1)".
• 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 Idle (Port) Bank 2, A/F Learn Value Low (Port) Bank 1, A/F Learn Value Low (Port) Bank 2, A/F Learn Value Mid No.1 (Port) Bank 1, A/F Learn Value Mid No.1 (Port) Bank 2, A/F Learn Value Mid No.2 (Port) Bank 1, A/F Learn Value Mid No.2 (Port) Bank 2, A/F Learn Value High (Port) Bank 1, A/F Learn Value High (Port) Bank 2, A/F Learn Value Idle Bank 1, A/F Learn Value Idle Bank 2, A/F Learn Value Low Bank 1, A/F Learn Value Low Bank 2, A/F Learn Value Mid No.1 Bank 1, A/F Learn Value Mid No.1 Bank 2, A/F Learn Value Mid No.2 Bank 1, A/F Learn Value Mid No.2 Bank 2, A/F Learn Value High Bank 1, A/F Learn Value High Bank 2, A/F Learn Value Low (Dual) Bank 1, A/F Learn Value Low (Dual) Bank 2, A/F Learn Value Mid (Dual) No.1 Bank 1, A/F Learn Value Mid (Dual) No.1 Bank 2, A/F Learn Value Mid (Dual) No.2 Bank 1, A/F Learn Value Mid (Dual) No.2 Bank 2, A/F Learn Value High (Dual) Bank 1 and A/F Learn Value High (Dual) Bank 2. (For vehicles equipped with a V type engine, check that both banks have the same correction tendency.) If the correction of either bank is -15% or less or 15% or higher, the air fuel ratio sensor or heated oxygen sensor of that bank may be malfunctioning.
• The following may cause a lean air fuel ratio (an operating range in which the air fuel ratio learned value correction is 15% or higher):
  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 (Bank 2)", "A/F Learn Value High Bank 1 (Bank 2)" or "A/F Learn Value High (Dual) Bank 1 (Bank 2)"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 (Bank 2)", "A/F Learn Value Low (Port) Bank 1 (Bank 2)", "A/F Learn Value Idle Bank 1 (Bank 2)", "A/F Learn Value Low Bank 1 (Bank 2)" or "A/F Learn Value Low (Dual) Bank 1 (Bank 2)" 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 -15% or less):
  1. Increase in the fuel injector assembly injection volume
  2. Purge VSV system

B

GO TO STEP 15

A

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Start the engine.

HINT:

Reproduce the vehicle conditions when the malfunction occurred. (such as after the engine is warmed up or after a cold start).

(e) Enter the following menus: Powertrain / Engine / Active Test / D-4S (Fuel Cut) / Data List / Engine Speed.

(f) According to the display on the Techstream, perform the Active Test and check for a malfunctioning cylinder.

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 #6" increases may be malfunctioning.
• If "Compression Leakage Count" in the Data List increases, misfiring due to insufficient compression may be occurring.

B

GO TO STEP 15

A

HINT:

If the vehicle does not support the Active Test "Check the Cylinder Compression", measure the compression pressure. If the compression pressure is normal, go to step 8 (PERFORM ACTIVE TEST USING TECHSTREAM (D-4S (INJECTION VOLUME))).

(a) Warm up the engine.

(b) Turn the engine switch off.

(c) Connect the Techstream to the DLC3.

(d) Turn the engine switch on (IG).

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine / Active Test / Check the Cylinder Compression / Data List / Compression / Engine Speed Cylinder #1 to #6 and Average Engine Speed of All Cylinder.

HINT:

To display the entire Data List, press the pull down menu button next to Primary. Then select Compression.

(g) Push the snapshot button to turn the snapshot function on.

HINT:

Using the snapshot function, data can be recorded during the Active Test.

(h) While the engine is not running, press the Active button to change Check the Cylinder Compression to "Start".

HINT:

After performing the above procedure, Check the Cylinder Compression will start. Fuel injection for all cylinders is prohibited and each cylinder engine speed measurement enters standby mode.

(i) Crank the engine for about 10 seconds.

(j) Monitor the engine speed (Engine Speed Cylinder #1 to #6 and Average Engine Speed of All Cylinder) displayed on the Techstream.

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 #6) 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:

• 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.
• Use a fully-charged battery.

(k) Stop cranking the engine, and then change "Check the Cylinder Compression" to "Stop" after the engine stops.

NOTICE:

• If the Active Test is changed to "Stop" while the engine is being cranked, the engine will start.
• When performing the Active Test, DTC P160400 (Startability Malfunction) may be stored.
• After performing the Active Test, make sure to check and clear DTCs.

(l) Push the snapshot button to turn the snapshot function off.

(m) Select "Stored Data" on the Techstream screen, select the recorded data and display the data as a graph.

HINT:

If the data is not displayed as a graph, the change of the values cannot be observed.

(n) Read the value.

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.

B

GO TO STEP 13

A

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with all the accessories switched off.

(e) Idle the engine.

(f) Enter the following menus: Powertrain / Engine / Active Test / D-4S (Injection Volume).

(g) According to the display on the Techstream, perform the Active Test and check the vehicle conditions when increasing and decreasing the fuel injection volume of port injection and direct injection.

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%).

B

GO TO STEP 14

A

(a) Check the ignition system.

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.

B

GO TO STEP 21

A

(a) Check the power source circuit, wire harness and connectors.

NEXT

GO TO STEP 21

(a) Clean off any deposits from the inside of the throttle body with motor assembly.

(b) Push open the throttle valve and wipe off any carbon from the valve and bore using a piece of cloth soaked in non-residue solvent.

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.

HINT:

The illustrations are for reference only. Actual parts may differ.

NEXT

(a) Perform "Inspection After Repair" after cleaning the throttle body with motor assembly.

Click here

(b) Connect the Techstream to the DLC3.

(c) Turn the engine switch on (IG).

(d) Turn the Techstream on.

(e) Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

(f) Allow the engine to idle for 3 minutes or more and confirm that the engine speed is within the specified range.

HINT:

If the engine is operated without performing learning value reset and idle learning after cleaning the deposits from the throttle body with motor assembly, the idle speed may increase.

NEXT

GO TO STEP 22

(a) Measure the cylinder compression pressure. If the compression pressure of a cylinder is low, inspect the engine assembly and repair or replace parts as necessary.

Click here

NEXT

GO TO STEP 21

(a) Replace the abnormal fuel injector assembly.

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.

  Click here

NEXT

GO TO STEP 22

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with all the accessories switched off.

(e) Enter the following menus: Powertrain / Engine / Data List / Mass Air Flow Sensor and Coolant Temperature.

(f) According to the display on the Techstream, read the Data List when the engine is running.

B

GO TO STEP 19

A

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with all the accessories switched off.

(e) Warm up the air fuel ratio sensor at an engine speed of 2500 rpm for 90 seconds.

(f) Idle the engine.

(g) Enter the following menus: Powertrain / Engine / Active Test / D-4S (Injection Volume) / Data List / Coolant Temperature, A/F (O2) Sensor Voltage B1S1, A/F (O2) Sensor Voltage B2S1, O2 Sensor Voltage B1S2 and O2 Sensor Voltage B2S2.

(h) According to the display on the Techstream, perform the Active Test and check the vehicle conditions when increasing and decreasing the fuel injection volume of port injection and direct injection.

NOTICE:

• The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.
• Read the output voltage immediately after warming up the air fuel ratio sensor and heated oxygen sensor 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 the minimum and maximum range of correction (e.g. -12.5% to 24.8%).

Standard:

B

GO TO STEP 18

C

GO TO STEP 20

A

(a) Replace the air fuel ratio sensor.

Click here

HINT:

Perform "Inspection After Repair" after replacing the air fuel ratio sensor.

Click here

(b) Replace the heated oxygen sensor.

Click here

HINT:

Perform "Inspection After Repair" after replacing the heated oxygen sensor.

Click here

NEXT

GO TO STEP 22

(a) Replace the fuel injector assemblies of all cylinders.

HINT:

Perform "Inspection After Repair" after replacing the fuel injector assembly.

Click here

NEXT

GO TO STEP 22

(a) Check for air leaks or blockage in the intake system components. If a connection problem or foreign matter is found, repair the connection or remove the foreign matter.

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.

NEXT

GO TO STEP 21

(a) Inspect other related components.

HINT:

If the malfunctioning part could not be determined by performing the preceding inspections, one of the following malfunctions is suspected.

• 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

NEXT

(a) Repair or replace the malfunctioning part.

(b) Perform "Inspection After Repair" after repairing or replacing the malfunctioning part.

Click here

NEXT

(a) Check that the idle has returned to normal.

NEXT

END