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P1084





2UR-FSE ENGINE CONTROL SYSTEM: SFI SYSTEM: P1081-P1084: HC Adsorber Switching Valve Bank 1 Stuck Open
P1084 - HC Adsorber Switching Valve Bank 2 Stuck Close

DESCRIPTION

The Hydro-Carbon Adsorber and Catalyst (HCAC) system is used to reduce the amount of HC in the exhaust emissions. In this system, the HC adsorber absorbs HC of the exhaust emissions when the catalyst is cold, and the catalyst purges the absorbed HC after the catalyst is warmed up.

When the catalyst is cold, the engine control module (ECM) turns on the HCAC VSV. The intake manifold pressure (vacuum) is applied to the HCAC actuator, and it opens the HCAC valve. The exhaust emissions flow to the HC adsorber.

After the catalyst is warmed up, the ECM turns off the HCAC VSV. The HCAC valve is opened by the return spring of the HCAC actuator. The exhaust emissions flow to the catalyst.

To monitor the HCAC valve operation, the ECM measures the exhaust gas temperatures (EGT) of the upstream HC adsorber and the upstream catalyst using the four EGT sensors.

When the HCAC valve is closing, the upstream exhaust gas temperature before the HC adsorber rising is large and the upstream exhaust gas temperature before the catalyst rising is small. When the HCAC valve is opening, the upstream exhaust gas temperature before the HC adsorber rising is small and the upstream exhaust gas temperature before the catalyst rising is large.













MONITOR DESCRIPTION

To monitor the HCAC valve operation, the ECM measures the upstream exhaust gas temperature before the HC adsorber (sensor 1) and upstream exhaust gas temperature before the catalyst (sensor 2) using the four exhaust gas temperature (EGT) sensors.

When the catalyst is cold, the HCAC valve will be closed. If the upstream exhaust gas temperature before the HC adsorber rising is small and the upstream exhaust gas temperature before the catalyst rising is large, the HCAC valve is forcibly closed when the ECT exceeds 60°C (140°F). Then, if the upstream exhaust gas temperature before the HC adsorber and the upstream exhaust gas temperature before the catalyst do not change, the ECM interprets this as an open stuck malfunction. When this malfunction is detected in consecutive driving cycles, the ECM illuminates the malfunction indicator lamp (MIL) and sets the DTC.

After the catalyst is warmed up, the HCAC valve will be opened. If the upstream exhaust gas temperature before the HC adsorber rising is large and the upstream exhaust gas temperature before the catalyst rising is small, the ECM interprets this as a closed stuck malfunction. When this malfunction is detected in consecutive driving cycles, the ECM illuminates the malfunction indicator lamp (MIL) and sets a DTC.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





P1081 and P1083 (1st detection)





P1082 and P1084 (2nd detection)





P1081 and P1083 (3rd detection)





TYPICAL MALFUNCTION THRESHOLDS

P1081 and P1083 (1st detection)





P1082 and P1084 (2nd detection)





P1081 and P1083 (3rd detection)





WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
When viewed from the rear of the engine assembly, Bank 1 is on the left side and Bank 2 is on the right side.

PROCEDURE

1. CHECK HCAC VSV

(a) Check that the wiring, hoses and connectors of the HCAC VSV are not disconnected and do not have any damage.

Result





C -- REPAIR OR REPLACE HARNESS OR CONNECTOR

B -- REPAIR OR REPLACE VACUUM HOSE
A -- Continue to next step.

2. CHECK FRONT EXHAUST PIPE

(a) Check that there is no exhaust gas leaking from the exhaust gas temperature sensor and front exhaust pipe.

(b) Check that the connectors of the exhaust gas temperature sensor, wiring, and vacuum hoses are not disconnected and do not have any damage.

Result





D -- REPAIR OR REPLACE HARNESS OR CONNECTOR

C -- REPAIR OR REPLACE VACUUM HOSE

B -- REPAIR EXHAUST GAS LEAK
A -- Continue to next step.

3. CHECK DTC OUTPUT

(a) Put the engine in inspection mode Inspection Mode Procedure.

(b) Connect the Techstream to the DLC3.

(c) Turn the Techstream ON.

(d) Switch the ECM from normal mode to check mode using the Techstream Inspection Mode Procedure.

(e) Warm up the engine at an engine coolant temperature of 80°C (176°F).

(f) Idle it for 3 minutes.

(g) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(h) Read DTCs.

Result





HINT
In this system, a single HCAC VSV operates the bank 1 and bank 2 HCAC actuator. Therefore, when the DTC for bank 1 and bank 2 are output simultaneously, there may be a problem in the HCAC VSV or the vacuum hose that connects to the HCAC VSV.

B -- PERFORM ACTIVE TEST USING TECHSTREAM (HCAC VSV)
A -- Continue to next step.

4. INSPECT EXHAUST GAS TEMPERATURE SENSOR

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG) and turn the Techstream ON.

(c) Enter the following menus: Powertrain / Engine and ECT/ Data List / All Data / Exhaust Temperature B1S1, Exhaust Temperature B1S2, Exhaust Temperature B2S1 and Exhaust Temperature B2S2.

(d) Put the engine in inspection mode Inspection Mode Procedure.

(e) Enter the following menus: Powertrain / Engine and ECT/ Data List / All Data / Exhaust Temperature B1S1, Exhaust Temperature B1S2, Exhaust Temperature B2S1 and Exhaust Temperature B2S2.

Result





HINT
Using the Techstream, measure the exhaust gas temperature, and inspect the exhaust gas temperature sensor and circuit condition. If the exhaust gas temperature is extremely low, there may be an open circuit. If the exhaust gas temperature is extremely high, there may be a short circuit. If there is no change in the exhaust gas temperature, there may be a malfunction in the exhaust gas temperature sensor itself.

Exhaust gas temperature sensor characteristic:





C -- REPLACE EXHAUST GAS TEMPERATURE SENSOR

B -- CHECK HARNESS AND CONNECTOR (EXHAUST GAS TEMPERATURE SENSOR - ECM)
A -- Continue to next step.

5. INSPECT HCAC VALVE SPRING

(a) Remove the front exhaust pipe Removal.

(b) Remove the heat insulator.





(c) Check that the HCAC valve springs are not disconnected and have no damage.

OK:

Spring is seated correctly and is not damaged.

NG -- REPLACE HCAC VALVE SPRING
OK -- Continue to next step.

6. CHECK HCAC VALVE AND HCAC ACTUATOR

(a) Disconnect the vacuum hose.

(b) Connect the hand vacuum pump to the HCAC actuator.

(c) Apply a vacuum of 36.8 kPa (276 mmHg, 10.9 in. Hg) or more to the actuator.





(d) Check that the cam of the HCAC valve rotates approximately 90° in the clockwise direction.

OK:

Rotates approximately 90° in clockwise direction.

HINT
If the results of this inspection are as specified, the HCAC actuator and HCAC valve are normal. In this case, there may be a malfunction in the exhaust gas temperature sensor.

NG -- INSPECT HCAC ACTUATOR

OK -- REPLACE EXHAUST GAS TEMPERATURE SENSOR

7. INSPECT HCAC ACTUATOR





(a) Connect a hand vacuum pump to the bank 2 HCAC actuator, apply a vacuum of 40 kPa (300 mmHg, 11.81 in. Hg), and plug the open port with a finger.

(b) Check that the rod of the HCAC actuator moves approximately 21.5 mm (0.846 in.) as shown in the illustration.

OK:

Moves approximately 21.5 mm (0.846 in.)

NG -- REPLACE HCAC ACTUATOR

OK -- REPLACE FRONT EXHAUST PIPE

8. PERFORM ACTIVE TEST USING TECHSTREAM (HCAC VSV)

(a) Put the engine in inspection mode Inspection Mode Procedure.

(b) Disconnect the vacuum hose.

(c) Connect the Techstream to the DLC3.

(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate HCAC VSV.





(e) Turn the HCAC VSV ON.

(f) Use your finger to confirm that the HCAC VSV has suction.

(g) Turn the HCAC VSV OFF.

(h) Use your finger to confirm that the HCAC VSV has no suction.

OK:

HCAC VSV functions normally

HINT
If the results of this inspection are as specified, the HCAC VSV is normal. In this case, there may be a leak in the vacuum hose that connects the HCAC VSV and HCAC actuator, or the vacuum hose may be damaged.

NG -- INSPECT HCAC VSV

OK -- REPAIR OR REPLACE VACUUM HOSE

9. INSPECT HCAC VSV

(a) Inspect the HCAC VSV Testing and Inspection.

OK:

HCAC VSV functions normally

NG -- REPLACE HCAC VSV
OK -- Continue to next step.

10. CHECK HARNESS AND CONNECTOR (HCAC VSV - ECM)





(a) Disconnect the HCAC VSV connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM

11. CHECK HARNESS AND CONNECTOR (EXHAUST GAS TEMPERATURE SENSOR - ECM)





(a) Disconnect the exhaust gas temperature sensor connectors.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE ECM

12. REPAIR EXHAUST GAS LEAK

(a) Repair the exhaust gas leakage point.

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

13. REPLACE HCAC VALVE SPRING

(a) Replace the HCAC valve spring.

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

14. REPLACE EXHAUST GAS TEMPERATURE SENSOR

(a) Replace the exhaust gas temperature sensor Removal.

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

15. REPLACE HCAC ACTUATOR

(a) Replace the HCAC actuator Removal.

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

16. REPLACE FRONT EXHAUST PIPE

(a) Replace the front exhaust pipe Removal.

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

17. REPAIR OR REPLACE VACUUM HOSE

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

18. REPLACE HCAC VSV

(a) Replace the HCAC VSV Removal.

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

19. REPAIR OR REPLACE HARNESS OR CONNECTOR

NEXT -- CHECK WHETHER DTC OUTPUT RECURS

20. REPLACE ECM

(a) Replace the ECM Removal.

NEXT -- Continue to next step.

21. CHECK WHETHER DTC OUTPUT RECURS

(a) Put the engine in inspection mode Inspection Mode Procedure.

(b) Connect the Techstream to the DLC3.

(c) Turn the Techstream ON.

(d) Switch the ECM from normal mode to check mode using the Techstream Inspection Mode Procedure.

(e) Warm up the engine at an engine coolant temperature of 80°C (176°F).

(f) Idle it for 3 minutes.

(g) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(h) Read DTCs.

(i) If no DTC is displayed, the repair has been successfully completed.

NEXT -- END
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