DTC P1605: Rough Idling [03/2019 - 11/2022]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
5. Read the DTCs.

   Powertrain > Engine and ECT > Trouble Codes 

   Result

   Result	Proceed to
   Only DTC P1605 is output	A
   DTCs other than P1605 are output	B

   HINT: 

   • If any DTCs other than P1605 is output, troubleshoot those DTCs first.
   • Using Freeze Frame Data, confirm the conditions the moment the DTC was stored and after the DTC was stored. This information can be useful when troubleshooting.

Result: 

B 

GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [03/2019 - 04/2020]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [04/2020 - 09/2022]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [09/2022 - 11/2022] 

Result: 

A 

See step  2

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Using the Techstream, confirm the vehicle conditions recorded in the Freeze Frame Data which were present when the DTC was stored.

   Powertrain > Engine and ECT > DTC (P1605) > Freeze Frame Data 

   Tester Display
   Compression Leakage Count
   Rough Idle Status
   Plural Cylinders Rough Idle
   Rough Idle #1
   Rough Idle #2
   Rough Idle #3
   Rough Idle #4

   Result

   Freeze Frame Data Item for DTC P1605			Suspected Area	Action	Proceed to
   Rough Idle #1 to #4 Plural Cylinders Rough Idle	Rough Idle Status	Compression Leakage Count
   "One of Rough Idle #1 to #4 is ON" and "Plural Cylinders Rough Idle is OFF"	"Misfire"	4 or less	Spark plug Ignition coil assembly Fuel injector assembly	Go to Rough Idling (from step 7)	A
   	One of the following is displayed: Continuous poor combustion Intermittent poor combustion Low frequency poor combustion	4 or less	Fuel injector assembly Spark plug Ignition coil assembly
   Plural Cylinders Rough Idle is ON	One of the following is displayed: Misfire Continuous poor combustion Intermittent poor combustion Low frequency poor combustion	4 or less	Mass air flow meter Fuel injector assembly Fuel system Air fuel ratio sensor	Go to Rough Idling (from step 15)	B
   "One of Rough Idle #1 to #4 is ON" or "Plural Cylinders Rough Idle is ON"	One of the following is displayed: Misfire Continuous poor combustion Intermittent poor combustion Low frequency poor combustion	5 or more	Pressure loss from valve damage, deposits jamming the valve etc.	Check compression and clean deposits in combustion chamber and intake system.	C

Result: 

B 

See step  4

Result: 

C 

See step  5

Result: 

A 

See step  3

1. Perform troubleshooting from Rough Idling step 7 (PERFORM ACTIVE TEST USING TECHSTREAM (CHECK THE CYLINDER COMPRESSION)) and onward.

   Refer to PROCEDURE - Step 7

   Result

   Proceed to
   NEXT

Result: 

NEXT 

GO TO ROUGH IDLING. Refer to  Rough Idling [01/2019 - 11/2022] 

1. Perform troubleshooting from Rough Idling step 15 (READ VALUE USING TECHSTREAM (MAF)) and onward.

   Refer to PROCEDURE - Step 15

   Result

   Proceed to
   NEXT

Result: 

NEXT 

GO TO ROUGH IDLING. Refer to  Rough Idling [01/2019 - 11/2022] 

1. Warm up the engine.
2. Turn the ignition switch off.
3. Connect the Techstream to the DLC3.
4. Turn the ignition switch to ON.
5. Turn the Techstream on.
6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Check the Cylinder Compression / Data List / Engine Speed of Cyl #1 to #4 and Av Engine Speed of All Cyl.

   Powertrain > Engine and ECT > Active Test 

   Active Test Display
   Check the Cylinder Compression

   Data List Display
   Engine Speed of Cyl #1
   Engine Speed of Cyl #2
   Engine Speed of Cyl #3
   Engine Speed of Cyl #4
   Av Engine Speed of All Cyl

   HINT: 

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

7. Push the snapshot button to turn the snapshot function on.

   HINT: 

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

8. While the engine is not running, press the Active Test button to change Check the Cylinder Compression to ON.

   HINT: 

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

9. Crank the engine for about 10 seconds.

   HINT: 

   Continue to crank the engine until the values change from the default value (51199 rpm).

10. Monitor the engine speed (Engine Speed of Cyl and Av Engine Speed of All Cyl) displayed on the Techstream.
    NOTE:

    • In order to protect the starter assembly, 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 ON and the engine has been cranked once, press Exit to return to the Active Test menu screen. Then change Check the Cylinder Compression to ON 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 of Cyl #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 ON and crank the engine again within 1 second.
11. Stop cranking the engine, and then change "Check the Cylinder Compression" to OFF after the engine stops.
    NOTE:

    • If the Active Test is changed to OFF while the engine is being cranked, the engine will start.
    • When performing the Active Test, DTC P1604 (Startability Malfunction) may be stored.
    • After performing the Active Test, make sure to check and clear DTCs.
12. Push the snapshot button to turn the snapshot function off.
13. 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.

14. Check the change in engine speed values.

    HINT: 

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

    Result

    Result	Proceed to
    There is no variation in "Engine Speed of Cyl" (All cylinders display approximately the same value for "Engine Speed of Cyl")	A
    There is variation in "Engine Speed of Cyl" (Only one cylinder displays a value for "Engine Speed of Cyl" that differs considerably)	B

Result: 

A 

CLEAN OFF ANY DEPOSITS 

Result: 

B 

See step  6

1. 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.

   Refer to PROCEDURE - Step 10

   Result

   Proceed to
   NEXT

Result: 

NEXT 

END