Fuel and Emissions Systems (4-cyl) Acura TSX II

Special Tools

SPECIAL TOOLS DESCRIPTION CHART

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Intermittent Failures

The term intermittent failure means a system may have had a failure, but it checks OK now. If the malfunction indicator lamp (MIL) on the dash does not come on, check for poor connections or loose terminals at all connectors related to the circuit that you are troubleshooting. If the MILwas on but then went out, the original problem may have been intermittent.

Service Information

Periodically, new ECM/PCM software or new service procedures may become available. Always check online for the latest software or service information related to the DTCs or symptoms you are troubleshooting.

Opens and Shorts

Open and short are common electrical terms. An open is a break in a wire or at a connection. A short is an accidental connection of a wire to ground or to another wire. In simple terms, this usually means something won't work at all. With complex electronics (such as ECMs or PCMs) this can sometimes mean something works, but not the way it's supposed to.

How to Use the HDS (Honda Diagnostic System)

If the MIL (malfunction indicator lamp) has come on

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1. Start the engine, and check the MIL (A). NOTE: If the ignition switch is turned to ON (II), and the engine is not started, the MIL stays on for 15-20 seconds (see «HOW TO SET READINESS CODES»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#fuel-and-emissions-systems-4-cyl) ).
2. If the MIL stays on, connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
3. Turn the ignition switch to ON (II).
4. Make sure the HDS communicates with the ECM/PCM and other vehicle systems. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#pgm-fi-system-4-cyl__dlc-circuit-troubleshooting) ).
5. Check the diagnostic trouble code (DTC) and note it. Also check the freeze data and/or on-board snapshot data, and download any data found. Then refer to the indicated DTCs troubleshooting, and begin the appropriate troubleshooting procedure. NOTE: Freeze data indicates the engine conditions when the first system malfunction, misfire, or fuel trim malfunction that activated the MIL was detected. The HDS can read the DTC, the freeze data, the on-board snapshot, the current data, and other engine control module (ECM) or powertrain control module (PCM) data. For specific operations, refer to the user's manual that came with the HDS.
6. If no DTCs are found, go to the MIL circuit troubleshooting (see «MIL CIRCUIT TROUBLESHOOTING»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#pgm-fi-system-4-cyl) ).

If the MIL did not stay on

If the MIL did not stay on but there is a driveability problem, do the symptom troubleshooting.

If you can't duplicate the DTC

Some of the troubleshooting requires you to reset the ECM/PCM and try to duplicate the DTC. If the problem is intermittent and you can't duplicate the code, do not continue through the procedure. To do so will only result in confusion and possibly, a needlessly replaced ECM/PCM.

HDS Clear Command

The ECM/PCM stores various specific data to correct the system even if there is no electrical power such as when the battery negative terminal is disconnected. Stored data based on failed parts should be cleared by using the CLEAR COMMAND of the HDS, if parts are replaced.

The HDS has three kinds of clear commands to meet this purpose. They are DTC clear, ECM/PCM reset, and CKP pattern clear. The DTC clear command erases all stored DTC codes, freeze data, on-board snapshot, and readiness codes. This must be done with the HDS after reproducing the DTC during troubleshooting.

The ECM/PCM reset command erases all stored DTC codes, freeze data, on-board snapshot, readiness codes, and all specific data to correct the system except CKP pattern. If the CKP pattern data in the ECM/PCM was cleared, you must do the CKP pattern learn procedure.

The CKP pattern clear command erases only CKP pattern data. This command is for repair of a misfire or the CKP sensor.

Scan Tool Clear Command

If you are using a generic scan tool to clear commands, be aware that there is only one setting for clearing the ECM/PCM, and it clears all commands at the same time (CKP pattern learn, idle learn, readiness codes, freeze data, on-board snapshot, and DTCs). After you clear all commands, you then need to do these procedures, in this order: ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ); CKP pattern learn procedure; test-drive to set readiness codes to complete (see HOW TO SET READINESS CODES ).

DTC Clear

1. Clear the DTC with the HDS while the engine is stopped.
2. Turn the ignition switch to LOCK (0).
3. Turn the ignition switch to ON (II), and wait 30 seconds.
4. Turn the ignition switch to LOCK (0), and disconnect the HDS from the DLC.

ECM/PCM Reset

1. Reset the ECM/PCM with the HDS while the engine is stopped.
2. Turn the ignition switch to LOCK (0).
3. Turn the ignition switch to ON (II), and wait 30 seconds.
4. Turn the ignition switch to LOCK (0), and disconnect the HDS from the DLC.
5. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#idle-control-system-4-cyl__ecmpcm-idle-learn-procedure) ).

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1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
2. Turn the ignition switch to ON (II).
3. Make sure the HDS communicates with the ECM/PCM and other vehicle systems. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#pgm-fi-system-4-cyl__dlc-circuit-troubleshooting) ).
4. Select CRANK PATTERN in the ADJUSTMENT MENU with the HDS.
5. Select CRANK PATTERN CLEAR, and clear the CKP pattern.
6. Select CRANK PATTERN LEARNING with the HDS, and follow the screen prompts.

Learn Procedure (without the HDS)

1. Start the engine. Hold the engine speed at 3, 000 RPM without load (A/T in P or N, M/T in neutral) until the radiator fan comes on.
2. Test-drive the vehicle on a level road: Decelerate (with the throttle fully closed) from an engine speed of 2, 500 RPM down to 1, 000 RPM with the A/T in 2, or the M/T in 2nd.
3. Repeat step 2 several times.
4. Turn the ignition switch to LOCK (0).
5. Turn the ignition switch to ON (II), and wait 30 seconds.

How to End a Troubleshooting Session (required after any troubleshooting)

1. Reset the ECM/PCM with the HDS.
2. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#idle-control-system-4-cyl__ecmpcm-idle-learn-procedure) ).
3. Turn the ignition switch to LOCK (0).
4. Disconnect the HDS from the DLC.

Note. The ECM/PCM is part of the immobilizer system. If you replace the ECM/PCM, it will have a different immobilizer code. For the engine to start, you must rewrite the immobilizer code with the HDS to instruct the new ECM/PCM and the immobilizer-keyless control unit to recognize each other's unique serial code.

How to Troubleshoot Circuits at the ECM/PCM Connectors

Note. The ECM/PCM overwrites data and monitors the EVAP system for about 40 minutes after the ignition switch is turned to LOCK (0). Jumping the SCS line after turning the ignition switch to LOCK (0) cancels this function. Disconnecting the ECM/PCM during this function, without jumping the SCS line first, can damage the ECM/PCM.

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1. Jump the SCS line with the HDS.
2. Disconnect ECM/PCM connectors A, B, and C. NOTE: Canada model: When disconnecting the ECM/PCM connectors, remove the ECM/PCM sub bracket (D).
3. When diagnosis/troubleshooting is done at the ECM/PCM connector, use the terminal test port (A) above the terminal you need to check.
4. Connect one side of the patch cord terminals (A) to a commercially available digital multimeter (B), and connect the other side of the terminals (C)to a commercially available banana jack (Pomona Electronics Tool No. 3563 or equivalent) (D).
5. Gently contact the pin probe (male) at the terminal test port from the terminal side. Do not force the tips into the terminals.

Note. For accurate results, always use the pin probe (male). To prevent damage to the connector terminals, do not insert test equipment probes, paper clips, or other substitutes as they can damage the terminals. Damaged terminals cause a poor connection and an incorrect measurement. Do not puncture the insulation on a wire. Punctures can cause poor or intermittent electrical connections.

Substituting the ECM/PCM

Special Tools Required

1. Honda Diagnostic System (HDS) tablet tester
2. Honda Interface Module (HIM) and an iN workstation with the latest HDS software version
3. HDS pocket tester
4. GNA600 and an iN workstation with the latest HDS software version
5. MVC1 unit with the latest control module (CM) update software installed

Any one of the above updating tools can be used.

Note. Use this procedure when you have to substitute a known-good ECM/PCM during troubleshooting procedures. Make sure the HDS/iN workstation or the MVCI has the latest HDS software version.

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1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.
2. Turn the ignition switch to ON (II).
3. Make sure the HDS communicates with the ECM/PCM and other vehicle systems. If it doesn't, go to the DLC circuit troubleshooting (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#pgm-fi-system-4-cyl__dlc-circuit-troubleshooting) ). If you are returning from DLC circuit troubleshooting, skip steps 4 and 5, then the clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/tsx/ii-2008-2014/remont/mechanical/#intake-air-system-4-cyl__throttle-body-cleaning) ) after substituting the ECM/PCM.
4. Select the INSPECTION MENU with the HDS.
5. Select the ETCS TEST, then select the TP POSITION CHECK, and follow the screen prompts. NOTE: If the TP POSITION CHECK indicates FAILED, continue this procedure.
6. Turn the ignition switch to LOCK (0).
7. Jump the SCS line with the HDS.
8. Remove the ECM/PCM cover (A).
9. Remove the battery setting plate (B), and reposition the battery away from the ECM/PCM. NOTE: Do not disconnect the battery terminals.
10. Remove the bolts (D).
11. Disconnect ECM/PCM connectors A, B, and C, then remove the ECM/PCM (E). NOTE: ECM/PCM connectors A, B, and C have symbols (A=[], B=delta, C=o) embossed on them for identification. Canada model: When disconnecting the ECM/PCM connectors, remove the ECM/PCM sub bracket (F).
12. Install a known-good ECM/PCM in the reverse order of removal.
13. Turn the ignition switch to ON (II). NOTE: DTC P0630 (VIN Not Programmed or Mismatch) may be stored because the VIN has not been programmed into the ECM/PCM; ignore it, and continue this procedure.
14. Manually input the VIN to the ECM/PCM with the HDS.
15. Select the IMMOBI SYSTEM with the HDS.
16. Enter the immobilizer ECM/PCM code that you got from the iN, and use the ECM/PCM replacement procedure in the IMMOBI MENU of the HDS; it allows you to start the engine.
17. Reset the ECM/PCM with the HDS.
18. Update the ECM/PCM if it does not have the latest software (see «ECM/PCM UPDATE»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#pgm-fi-system-4-cyl__ecmpcm-update) ).
19. If the TP POSITION CHECK failed in step 5 , clean the throttle body (see «THROTTLE BODY CLEANING»(/acura/tsx/ii-2008-2014/remont/mechanical/#intake-air-system-4-cyl__throttle-body-cleaning) ).
20. Do the ECM/PCM idle learn procedure (see «ECM/PCM IDLE LEARN PROCEDURE»(/acura/tsx/ii-2008-2014/remont/testing-diagnostics/#idle-control-system-4-cyl__ecmpcm-idle-learn-procedure) ).
21. Do the CKP pattern clear/CKP pattern learn procedure.

OBD Status

The OBD status shows the current system status of each DTC and all of the parameters. This function is used to see if the repair was successfully completed. The results of diagnostic tests for the DTC are displayed as

1. PASSED: The on board diagnosis is successfully finished.
2. FAILED: The on board diagnosis has finished but failed.
3. EXECUTING: The vehicle is in enable criteria conditions for the DTC, and the on board diagnosis is running.
4. NOT COMPLETED: The on board diagnosis was running but is out of the enable conditions of the DTC.
5. OUT OF CONDITION: The vehicle has stayed out of the enable conditions for the DTC.

DTC Troubleshooting Index

DTC TROUBLESHOOTING CHART

Note. The above DTCs are indicated when the PGM-FI system is selected with the HDS.

Some automatic transmission DTCs cause the MIL to come on. If the MIL is on and no DTCs are indicated in the PGM-FI system, select the A/T system, and check for automatic transmission DTCs.

*: These DTCs are indicated by a blinking MIL when the SCS line is jumped with the HDS. Some DTCs do not cause the MIL to blink when the SCS line is jumped. The last four characters of these DTCs are shown in the gauge display.

*1:A/T

*2: MfT

Symptom Troubleshooting Index

When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.

SYMPTOM TROUBLESHOOTING CHART

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Electronic Control Systems

The functions of the fuel and emission control systems are managed by the engine control module (ECM) on vehicles with manual transmissions or the powertrain control module (PCM) on vehicles with automatic transmissions.

Self-Diagnosis

The ECM/PCM detects the failure of a signal from a sensor or from another control unit and stores a Pending DTC or a Confirmed DTC. Depending on the failure, a Confirmed DTC is stored in either the first or the second drive cycle. When a Confirmed DTC is stored, the ECM/PCM turns on the malfunction indicator lamp (MIL) by a signal sent to the gauge via F-CAN.

1. One Drive Cycle Detection Method When an abnormality occurs in the signal from a sensor or from another control unit, the ECM/PCM stores a Confirmed DTC and turns on the MIL immediately.
2. Two Drive Cycle Detection Method

When an abnormality occurs in the signal from a sensor or from another control unit in the first drive cycle, the ECM/PCM stores a Pending DTC. The MIL does not come on at this time. If the failure continues in the second drive cycle, the ECM/PCM stores a Confirmed DTC and turns on the MIL.

Fail-Safe Function

When an abnormality occurs in the signal from a sensor or from another control unit, the ECM/PCM ignores that signal and substitutes a pre-programmed value for them that allows the engine to continue running. This causes a Confirmed DTC to be stored and the MIL to come on.

MIL Bulb Check and Readiness Code Condition

When the ignition switch is turned to ON (II), the ECM/PCM turns on the MIL via the F-CAN circuit for about 15 to 20 seconds to check the bulb condition. If any readiness codes are not set to complete, the MIL flashes five times. If all readiness codes are set to complete, the MIL goes off.

Self Shut Down (SSD) Mode

After the ignition switch is turned to LOCK (0), the ECM/PCM stays on (about 40 minutes). If the ECM/PCM connector is disconnected during this time, the ECM/PCM may be damaged. To cancel this mode, disconnect the negative cable from the battery or jump the SCS line with the HDS after the ignition switch is turned to LOCK (0).

ECM/PCM Inputs and Outputs at ECM/PCM Connector A ([]) (49P)

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TERMINAL DESCRIPTION CHART

*1:A/T

ECM/PCM Inputs and Outputs at ECM/PCM Connector A ([]) (49P)

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TERMINAL DESCRIPTION CHART

ECM/PCM Inputs and Outputs at ECM/PCM Connector A ([]) (49P)

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TERMINAL DESCRIPTION CHART

ECM/PCM Inputs and Outputs at ECM/PCM Connector A ([]) (49P)

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TERMINAL DESCRIPTION CHART

*1:A/T

*2:MfT

ECM/PCM Inputs and Outputs at ECM/PCM Connector B (A) (delta) (49P)

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TERMINAL DESCRIPTION CHART

ECM/PCM Inputs and Outputs at ECM/PCM Connector B (A) (delta) (49P)

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TERMINAL DESCRIPTION CHART

ECM/PCM Inputs and Outputs at ECM/PCM Connector B (delta) (49P)

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TERMINAL DESCRIPTION CHART

*1:A/T

ECM/PCM Inputs and Outputs at ECM/PCM Connector C (o) (49P)

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TERMINAL DESCRIPTION CHART

ECM/PCM Inputs and Outputs at ECM/PCM Connector C (o) (49P)

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TERMINAL DESCRIPTION CHART

*2: M/T

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PGM-FI System

The programmed fuel injection (PGM-FI) system is a sequential multiport fuel injection system.

Alternator Control

The alternator signals the ECM/PCM during charging.

The ECM/PCM then controls the voltage generated at the alternator according to the electrical load determined by the electrical load detector (ELD) and the driving mode. This reduces engine load to improve fuel economy.

Air Conditioning (A/C) Compressor Clutch Relay

When the ECM/PCM receives a demand for cooling from the A/C system, it delays the compressor from being energized, and enriches the mixture to assure a smooth transition to the A/C mode.

Air Fuel Ratio (A/F) Sensor

The A/F sensor operates over a wide air/fuel range. The A/F sensor is installed upstream of the warm up three way catalytic converter (WU-TWC), and it sends signals to the ECM/PCM which varies the duration of fuel injection accordingly

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Barometric Pressure (BARO) Sensor

The BARO sensor is inside the ECM/PCM. It converts atmospheric pressure into a voltage signal that is used by the ECM/PCM to modify the basic duration of the fuel injection discharge.

Camshaft Position (CMP) Sensor B

CMP sensor B detects the position of the No. 1 cylinder as a reference for sequential fuel injection to each cylinder.

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Crankshaft Position (CKP) Sensor

The CKP sensor detects crankshaft speed, and is used by the ECM/PCM to determine ignition timing, timing for the fuel injection of each cylinder, and engine misfire detection.

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Engine Coolant Temperature (ECT) Sensors 1 and 2

ECT sensors 1 and 2 are temperature dependent resistors (thermistors). The resistance decreases as the engine coolant temperature increases.

ECT sensor 1

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Ignition Timing Control

The ECM/PCM contains the memory for basic ignition timing at various engine speeds and manifold absolute pressures. It also adjusts the timing according to engine coolant temperature and intake air temperature.

Injector Timing and Duration

The ECM/PCM contains the memory for basic discharge duration at various engine speeds and manifold pressures. The basic discharge duration, after being read out from the memory, is further modified by signals sent from various sensors to obtain the final discharge duration.

By monitoring long term fuel trim, the ECM/PCM detects long term malfunctions in the fuel system and sets diagnostic trouble codes (DTCs) if needed.

Knock Sensor

The knock control system adjusts the ignition timing to minimize knock.

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Malfunction Indicator Lamp (MIL) Indication (in relation to Readiness Codes)

The vehicle has certain readiness codes that are part of the on-board diagnostics for the emissions systems. If the vehicle's battery has been disconnected or gone dead, if DTCs have been cleared, or if the ECM/PCM has been reset, these codes are reset. In some states, part of the emissions testing is to make sure these codes are set to complete. If all of them are not set to complete, the vehicle may fail the test, or the test cannot be finished.

To check if the readiness codes are set to complete, turn the ignition switch to ON (II), but do not start the engine. The MIL will come on for 15-20 seconds. If it then goes off, the readiness codes are complete. If it flashes five times, one or more readiness codes are not complete. To set each code, drive the vehicle or run the engine as described in the procedures (see HOW TO SET READINESS CODES ).

Manifold Absolute Pressure (MAP) Sensor

The MAP sensor converts manifold absolute pressures into electrical signals that are sent to the ECM/PCM.

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Mass Airflow (MAF) Sensor/Intake Air Temperature (IAT) Sensor

The mass airflow (MAF) sensor/intake air temperature (IAT) sensor contains a hot wire sensor, a cold wire sensor and a thermistor. It is in the intake air passage. The resistance of the hot wire sensor, the cold wire sensor, and the thermistor changes due to intake air temperature and airflow. The control circuit in the MAF sensor controls the current to keep the hot wire at a set temperature. The current is converted to voltage in the control circuit, then output to the ECM/PCM.

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Output Shaft (Countershaft) Speed Sensor

This sensor detects countershaft speed.

M/T

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A/T

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Secondary Heated Oxygen Sensor (Secondary H02S)

The secondary H02S detects the oxygen content in the exhaust gas downstream of the warm up three way catalytic converter (WU-TWC), and sends signals to the ECM/PCM. To stabilize its output, the sensor has an internal heater. The ECM/PCM compares the H02S output with the A/F sensor output to determine catalyst efficiency. A secondary H02S is installed downstream of the WU-TWC.

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Electronic Throttle Control System

The throttle is electronically controlled. Refer to the system diagram to see a functional layout of the system.

Idle control: When the engine is idling, the ECM/PCM controls the throttle actuator to maintain the proper idle speed according to engine loads.

Acceleration control: When the accelerator pedal is pressed, the ECM/PCM opens the throttle valve based on the accelerator pedal position (APP) sensor signal.

Cruise control: The ECM/PCM controls the throttle actuator to maintain the set speed when the cruise control is operating. The throttle actuator takes the place of the cruise control actuator.

Accelerator Pedal Position (APP) Sensor

As the accelerator pedal position changes, the sensor varies the signal voltage to the ECM/PCM which then controls the throttle position.

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Throttle Body

The throttle body is a single-barrel side draft type. The lower portion of the throttle valve is heated by engine coolant from the cylinder head to prevent icing of the throttle plate.

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Electronic Throttle Control System Diagram

The electronic throttle control system consists of the throttle actuator, throttle position (TP) sensor A/B, accelerator pedal position (APP) sensor A/B, the electronic throttle control system (ETCS) control relay, and the ECM/PCM.

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VTEC/VTC

1. The i-VTEC system has a variable valve timing control (VTC) mechanism on the intake camshaft in addition to the usual VTEC. This system improves fuel efficiency and reduces exhaust emissions at all levels of engine speed, vehicle speed, and engine load.
2. The VTEC system changes the intake valve lift and timing by using more than one cam profile.
3. The VTC system changes the phase of the intake camshaft via oil pressure. It changes the intake valve timing continuously.

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DRIVING CONDITION CHART

VTC System

1. The VTC system makes continuous intake valve timing changes based on operating conditions.
2. Intake valve timing is optimized to allow the engine to produce maximum power.
3. Cam angle is advanced to obtain the EGR effect and reduce pumping loss. The intake valve is closed quickly to reduce the entry of the air/fuel mixture into the intake port and improve the charging effect.
4. The system reduces the cam advance at idle, stabilizes combustion, and reduces engine speed.
5. If a malfunction occurs, the VTC system control is disabled and the valve timing is fixed at the fully retarded position.

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VTC System Diagram

The VTC oil control solenoid valve controls oil pressure to the advance chamber/retard chamber of the VTC actuator according to a signal from the ECM/PCM. When the VTC actuator vanes rotate to the advance or retard position, the intake camshaft timing is changed.

CMP sensor A detects the intake camshaft angle and sends the information to the ECM/PCM. The ECM/PCM controls the VTC oil control solenoid valve as the intake camshaft angle changes.

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Intake valve side

1. The VTEC system changes the cam profile to correspond to engine speed. It maximizes torque at low engine speed and output at high engine speed.
2. The low lift cam is used at low engine speeds, and the high lift cam is used at high engine speeds.
3. The rocker arm oil control solenoid switches the intake valve side of the VTEC system on and off; the solenoid is controlled by the ECM/PCM.
4. The rocker arm oil pressure switch detects VTEC system oil pressure and sends this information to the ECM/PCM.

ENGINE SPEED SPECIFICATION CHART

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VTEC System Operation

At low engine speed, the rocker arm oil control solenoid is turned off by the ECM/PCM. Oil pressure from the rocker arm oil control valve does not enter the intake rocker shaft. Each intake rocker arm is separated by a return spring and the intake secondary rocker arm is lifted by the low lift cam lobe.

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At high engine speed, the rocker arm oil control solenoid is turned on by the ECM/PCM. Oil pressure from the rocker arm control solenoid enters the primary intake rocker arm via the intake rocker shaft, and it moves the VTEC switching piston in the rocker arm.

This causes the VTEC switching piston to slide into the intake mid rocker arm and the intake secondary rocker arm, locking the rocker arms together. Both intake rocker arms are lifted by the high lift cam lobe.

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Idle Control System

When the engine is cold, if the A/C compressor is on, the transmission is in gear, the brake pedal is pressed, or the alternator is charging, the ECM/PCM sends signals to the throttle actuator to maintain the correct idle speed.

Brake Pedal Position Switch

The brake pedal position switch signals the ECM/PCM when the brake pedal is pressed.

Fuel Cutoff Control

During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy at engine speeds over 850 RPM (A/T) or 1, 000 RPM (M/T). Fuel cutoff also occurs when the engine speed exceeds 7, 300 RPM, regardless of the position of the throttle valve, to protect the engine from over-revving. When the vehicle is stopped, the ECM/PCM cuts the fuel at engine speeds over 5, 000 RPM (A/T), 4, 000 RPM (M/T). On a cold engine, fuel cut occurs at a lower engine speed.

Fuel Pump Control

When the ignition switch is turned to ON (II), the ECM/PCM grounds PGM-FI main relay 2 which feeds current to the fuel pump for 2 seconds to pressurize the fuel system. When the engine starts, the ECM/PCM grounds PGM-FI main relay 2 and feeds current to the fuel pump. When the engine is not running and the ignition is ON (II), the ECM/PCM cuts ground to PGM-FI main relay 2 which cuts current to the fuel pump.

PGM-FI Main Relays 1 and 2

PGM-FI main relay 1 is energized whenever the ignition switch is turned to ON (II) to supply battery voltage to the ECM/PCM, power to the injectors, and power for PGM-FI main relay 2. PGM-FI main relay 2 is energized to supply power to the fuel pump for 2 seconds when the ignition switch is turned to ON (II), and when the engine is cranking or running.

Warm Up Three Way Catalytic Converter (WU-TWC) and Under-floor Three Way Catalytic Converter (Under-floor TWC)

The WU-TWC/Under-Floor TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in the exhaust gas to carbon dioxide (C02), nitrogen (N2), and water vapor.

WU-TWC (ATTACHED TO THE CYLINDER HEAD)

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UNDER-FLOOR TWC

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Positive Crankcase Ventilation (PCV) System

The PCV valve prevents blow-by gasses from escaping into the atmosphere by venting them into the intake manifold.

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Evaporative Emission (EVAP) Control System

Refer to the system diagram to see a functional layout of the system.

EVAP Canister

The EVAP canister temporarily stores fuel vapor from the fuel tank until it can be purged back into the engine and burned.

EVAP Canister Purge Valve

When the engine coolant temperature is below 131 °F (55 °C), the ECM/PCM turns off the EVAP canister purge valve which cuts vacuum to the EVAP canister.

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Fuel Tank Pressure (FTP) Sensor

The FTP sensor converts fuel tank absolute pressure into an electrical input to the ECM/PCM.

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EVAP Canister Vent Shut Valve

The EVAP canister vent shut valve is on the EVAP canister.

The EVAP canister vent shut valve controls the venting of the EVAP canister.

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Evaporative Emission (EVAP) Control Diagram

The EVAP controls minimize the amount of fuel vapor escaping to the atmosphere. Vapor from the fuel tank is temporarily stored in the EVAP canister until it can be purged from the canister into the engine and burned.

1. The EVAP canister is purged by drawing fresh air through it and into a port on the intake manifold. The purging vacuum is controlled by the EVAP canister purge valve, which operates whenever the engine coolant temperature is above 131 °F (55 °C).
2. During refueling, the fuel tank vapor control valve opens from pressure in the fuel tank and vents the fuel vapor to the EVAP canister.

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Fuel Cap Warning Message

The ECM/PCM detects a loose or missing fuel fill cap as an evaporative system leak and alerts the driver by showing a warning message in the gauge display.

The first time a leak is detected, a TIGHTEN FUEL CAP message appears on the gauge display (A). To scroll to another message, press the select/reset button. The TIGHTEN FUEL CAP message appears each time you restart the engine until the system turns the message off.

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Procedure

1. Tighten the fuel fill cap until it clicks.
2. Clear the Pending DTC with the HDS.
3. Verify there is no leak by doing the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.

1. Tighten the fuel fill cap until it clicks.
2. Start the engine, then turn the ignition switch to LOCK (0).
3. Repeat step 2 two more times.

The vehicle has certain readiness codes that are part of the on-board diagnostics for the emissions systems. If the vehicle's battery has been disconnected or gone dead, if DTCs have been cleared, or if the ECM/PCM has been reset, these readiness codes are reset to incomplete. In some states, part of the emissions testing is to make sure these codes are set to complete. If all of them are not set to complete, the vehicle may fail the emission test, or the test cannot be finished.

To check if the readiness codes are set to complete, turn the ignition switch to ON (II), but do not start the engine. The MIL comes on for 15-20 seconds. If it then goes off, the readiness codes are set to complete. If it flashes five times, one or more readiness codes are not set to complete. To set readiness codes from incomplete to complete, do the procedure for the appropriate code.

To check the status of a specific DTC system, check the OBD status in the DTC MENU with the HDS (see DTC TROUBLESHOOTING INDEX ). This screen displays the DTC, the current data list of the enable criteria, and the status of the readiness testing.

Catalytic Converter Monitor and Readiness Code

Note. During the procedure, do not turn the ignition switch to ACC (I) or LOCK (0). All readiness codes are cleared when the battery is disconnected, if DTCs have been cleared, or if the ECM/PCM is reset with the HDS. Low ambient temperatures or excessive stop-and-go traffic may increase the drive time needed to switch the readiness code from incomplete to complete. The readiness code will not switch to complete until all the enable criteria are met. If a fault in the secondary H02S system caused the MIL to come on, the readiness code cannot be set to complete until you correct the fault.

Enable Criteria

1. ECT SENSOR 1 at 158 °F (70 °C) or more.
2. IAT SENSOR at 20 °F (-7 °C) or more.
3. Vehicle speed above 25 mph (40 km/h).

1. Connect the HDS to the vehicle's data link connector (DLC), and bring up the READINESS CODES screen for Catalyst in the DTCs MENU.
2. Start the engine.
3. Test-drive the vehicle under stop-and-go conditions with short periods of steady cruise. After about 5 miles (8 km), the readiness code should switch to complete.
4. If the readiness code is still not set to complete, check for a Pending DTC with the HDS. If there is no DTC, one or more of the enable criteria were probably not met; repeat the procedure.

Evaporative Emission (EVAP) Control System Monitor and Readiness Code

Note. All readiness codes are cleared when the battery is disconnected, if DTCs have been cleared, or if the ECM/PCM is reset with the HDS.

1. Battery voltage is more than 10.5 V.
2. Engine at idle.
3. ECT SENSOR 1 and 2 between 176 °F (80 °C) and 212°F (100°C).
4. MAP SENSOR less than 46.6 kPa (14 inHg, 350 mmHg).
5. Vehicle speed 0 mph (0 km/h).
6. IAT SENSOR between 32 °F (0 °C) and 212 °F (100 °C).

1. Connect the HDS to the DLC.
2. Start the engine.
3. Select EVAP TEST in the INSPECTION MENU with the HDS, then select the FUNCTION TEST in the EVAP TEST MENU. If the result is normal, readiness is complete. If the result is not normal, go to the next step.
4. Check for a Pending DTC. If there is no DTC, one or more of the enable criteria were probably not met; repeat the procedure.

Air Fuel Ratio (A/F) Sensor Monitor and Readiness Code

Note. During the procedure, do not turn the ignition switch to ACC (I) or LOCK (0). All readiness codes are cleared when the battery is disconnected, if DTCs have been cleared, or if the ECM/PCM is reset with the HDS.

ECT SENSOR 1 at 140 °F (60 °C) or more.

1. Start the engine.
2. Test-drive the vehicle under stop-and-go conditions with short periods of steady cruise. During the drive, decelerate (with the throttle fully closed) for 5 seconds. After about 3.5 miles (5.6 km), the readiness code should switch from incomplete to complete.
3. Check the readiness codes screen for the AIR FUEL RATIO (A/F) SENSOR in the DTCs MENU with the HDS. If the screen shows complete, readiness is complete. If the screen shows not complete, go to the next step.
4. Check for a Pending DTC. If there is no DTC, the enable criteria was probably not met. Select the DATA LIST MENU. Check ECT SENSOR 1 in the ALL DATA LIST with the HDS. If ECT SENSOR 1 is less than 140 °F (60 °C), run the engine until it is more than 140 °F (60 °C), then repeat the procedure.

Air Fuel Ratio (A/F) Sensor Heater Monitor Readiness Code

Note. All readiness codes are cleared when the battery is disconnected, if DTCs have been cleared, or if the ECM/PCM is reset with the HDS.

1. Start the engine, and let it idle for 1 minute. The readiness code should switch from incomplete to complete.
2. If the readiness code is still not set to complete, check for a Pending DTC. If there is no DTC, repeat the procedure.

Misfire Monitor and Readiness Code

1. This readiness code is always set to available because misfiring is continuously monitored.
2. Monitoring pauses, and the misfire counter resets, if the vehicle is driven over a rough road.
3. Monitoring also pauses, and the misfire counter holds at its current value, if the throttle position changes more than a predetermined value, or if driving conditions fall outside the range of any related enable criteria.

Fuel System Monitor and Readiness Code

1. This readiness code is always set to available because the fuel system is continuously monitored during closed loop operation.
2. Monitoring pauses when the catalytic converter, the EVAP control system, and the A/F sensor monitors are active.
3. Monitoring also pauses when any related enable criteria are not being met. Monitoring resumes when the enable criteria is again being met.

Comprehensive Component Monitor and Readiness Code

This readiness code is always set to available because the comprehensive component monitor is continuously running whenever the engine is cranking or running.

See also:
• DLC CIRCUIT TROUBLESHOOTING
• MIL CIRCUIT TROUBLESHOOTING
• ECM/PCM IDLE LEARN PROCEDURE
• THROTTLE BODY CLEANING
• ECM/PCM UPDATE
• P0010 (56)
• P0011(56)
• P0101(50)
• P0102(50)
• P0103(50)
• P0107(3)
• P0108(3)
• P011(10)
• P0112(10)
• P0113(10)
• P0116(86)
• P0117(6)
• P0118(6)
• P0122(7)
• P0123(7)
• P0125(86)
• P0128 (87)
• P0133(61)
• P0134(41)
• P0135(41)
• P0137(63)
• P0138(63)
• P0139 (63)
• P0141 (65)
• P0171 (45)
• P0222 (7)
• P0223 (7)
• P0300(211)
• P0301(71)
• P0325 (23)
• P0335 (4)
• P0339 (4)
• P0340 (57)
• P0341 (57)
• P0344 (57)
• P0351 (71)
• P0365 (8)
• P0369 (8)
• P0420 (67)
• P0443(92)
• P0451 (91)
• P0452(91)
• P0453(91)
• P0455 (90)
• P0457
• P0461
• P0462
• P0463
• P0496 (92)
• P0497(90)
• P0498(117)
• P0499(117)
• P0506(14)
• P0507 (14)
• P050A (167)
• P050B (167)
• P0532
• P0533
• P0562
• P0563
• P0602 (196)
• P0606(-)
• P062F (131)
• P0630(139)
• P0685(135)
• P0720 (122)
• P1009(56)
• P1109(13)
• P1116(86)
• P1128(5)
• P1129(5)
• P1157(48)
• P1172(61)
• P1297
• P1298
• P1454 (01)
• P1458(91)
• P145C (90)
• P1549
• P1658(40)
• P1659(40)
• P1683(40)
• P1684(40)
• P16BB
• P16BC
• P2101 (40)
• P2118(40)
• P2122(37)
• P2123(37)
• P2127(37)
• P2128(37)
• P2135 (7)
• P2138(37)
• P2176(40)
• P2183(192)
• P2184(192)
• P2185 (192)
• P2195(48)
• P2227(13)
• P2228 (13)
• P2229(13)
• P2238 (48)
• P2252(48)
• P2270 (63)
• P2279 (109)
• P2610(132)
• P2646 (22)
• P2647(22)
• P2648(21)
• P2649(21)
• P2A00(61)
• U0029(126)
• U0122
• U0131
• U0155(126)
• U0300(131)
• BATTERY TEST
• CLUTCH INTERLOCK SWITCH REPLACEMENT
• FUEL PRESSURE TEST
• FUEL PUMP CIRCUIT TROUBLESHOOTING
• SYSTEM CHECK
• AIR CLEANER REMOVAL/INSTALLATION
• IDLE SPEED INSPECTION
• A/C SIGNAL CIRCUIT TROUBLESHOOTING
• APP SENSOR SIGNAL INSPECTION
• FUEL PUMP/FUEL GAUGE SENDING UNIT REPLACEMENT
• FUEL CAP WARNING MESSAGE SYSTEM TROUBLESHOOTING
• HOW TO SET READINESS CODES
• DTC TROUBLESHOOTING INDEX