Emissions System Jeep Grand Cherokee WK

EMISSION CONTROL SYSTEM - DIESEL

The Engine Control Module (ECM) controls many different circuits in the fuel injection and engine systems. If the ECM senses a problem with a monitored circuit that indicates an actual problem, a Diagnostic Trouble Code (DTC) will be stored in the ECM's memory, and eventually may illuminate the MIL (Malfunction Indicator Lamp) constantly while the key is on. If the problem is repaired, or is intermittent, the ECM will erase the DTC after 40 warm-up cycles without the fault detected. A warm-up cycle consists of starting the vehicle when the engine is cold, then the engine is warmed up to a certain temperature, and finally, the engine temperature falls to a normal operating temperature, then the key is turned off.

Certain criteria must be met for a DTC to be entered into ECM memory. The criteria may be a specific range of engine RPM, engine or fuel temperature and/or input voltage to the ECM. A DTC indicates that the ECM has identified an abnormal signal in a circuit or the system.

There are several operating conditions that the ECM does not monitor and set a DTC for.

ECM MONITORED SYSTEMS

The ECM can detect certain problems in the electrical system.

Open or Shorted Circuit - The ECM will not distinguish between an open or a short to ground, however the ECM can determine if there is excessive current on a circuit, such as a short to voltage or a decrease in component resistance.

Output Device Current Flow - The ECM senses whether the output devices are electrically connected.

If there is a problem with the circuit, the ECM senses whether the circuit is open, shorted to ground (-), or shorted to (+) voltage.

Fuel Pressure: Fuel pressure is controlled by the fuel injection pump and fuel pressure solenoid. The ECM uses a fuel pressure sensor to determine if a fuel pressure problem exists.

Fuel Injector Malfunctions: The ECM can determine if a fuel injector has an electrical problem. The fuel injectors on the diesel engine are controlled by the ECM.

ECM NON-MONITORED SYSTEMS

The ECM does not monitor the following circuits, systems or conditions that could have malfunctions that result in driveability problems. A DTC will not be displayed for these conditions.

Cylinder Compression: The ECM cannot detect uneven, low, or high engine cylinder compression.

Exhaust System: The ECM cannot detect a plugged, restricted or leaking exhaust system except in the case of a exhaust particulate filter. The ECM monitors the exhaust particulate filter with a pressure differential sensor which signals the ECM when it is time to run the burn off cycle.

Vacuum Assist: Leaks or restrictions in the vacuum circuits of the Exhaust Gas Recirculation System (EGR) are not monitored by the ECM.

ECM System Ground: The ECM cannot determine a poor system ground. However, a DTC may be generated as a result of this condition.

ECM/PCM Connector Engagement: The ECM cannot determine spread or damaged connector pins. However, a DTC may be generated as a result of this condition.

HIGH AND LOW LIMITS

The ECM compares input signals from each input device. It has high and low limits that are programmed into it for that device. If the inputs are not within specifications and other DTC criteria are met, a DTC will be stored in memory. Other DTC criteria might include engine RPM limits or input voltages from other sensors or switches. The other inputs might have to be sensed by the ECM when it senses a high or low input voltage from the control system device in question.

CIRCUIT ACTUATION TEST MODE

The Circuit Actuation Test Mode checks for proper operation of output circuits or devices the Powertrain Control Module (PCM) may not internally recognize. The PCM attempts to activate these outputs and allow an observer to verify proper operation. Most of the tests provide an audible or visual indication of device operation (click of relay contacts, fuel spray, etc.). Except for intermittent conditions, if a device functions properly during testing, assume the device, its associated wiring, and driver circuit work correctly. Connect a scan tool to the data link connector and access the Actuators screen.

COMPONENT MONITORS

There are several components that will affect vehicle emissions if they malfunction. If one of these components malfunctions the Malfunction Indicator Lamp (MIL) will illuminate.

Some of the component monitors are checking for proper operation of the part. Electrically operated components now have input (rationality) and output (functionality) checks. Previously, a component like the Throttle Position sensor (TPS) was checked by the PCM for an open or shorted circuit. If one of these conditions occurred, a DTC was set. Now there is a check to ensure that the component is working. This is done by watching for a TPS indication of a greater or lesser throttle opening than MAP and engine RPM indicate. In the case of the TPS, if engine vacuum is high and engine RPM is 1600 or greater, and the TPS indicates a large throttle opening, a DTC will be set. The same applies to low vacuum if the TPS indicates a small throttle opening.

All open/short circuit checks, or any component that has an associated limp-in, will set a fault after 1 trip with the malfunction present. Components without an associated limp-in will take two trips to illuminate the MIL.

STATE DISPLAY TEST MODE

The switch inputs to the Powertrain Control Module (PCM) have two recognized states; HIGH and LOW. For this reason, the PCM cannot recognize the difference between a selected switch position versus an open circuit, a short circuit, or a defective switch. If the State Display screen shows the change from HIGH to LOW or LOW to HIGH, assume the entire switch circuit to the PCM functions properly. Connect a diagnostic scan tool to the data link connector and access the state display screen. Then access either State Display Inputs and Outputs or State Display Sensors.

DIAGNOSTIC TROUBLE CODES

A Diagnostic Trouble Code (DTC) indicates the PCM has recognized an abnormal condition in the system.

Remember that DTC's are the results of a system or circuit failure, but do not directly identify the failed component or components.

BULB CHECK

Each time the ignition key is turned to the ON position, the malfunction indicator (check engine) lamp on the instrument panel should illuminate for approximately 2 seconds then go out. This is done for a bulb check.

OBTAINING DTC'S

1. Obtain the applicable Powertrain Diagnostic Information.
2. Obtain the appropriate scan tool.
3. Connect the appropriate scan tool to the data link (diagnostic) connector. This connector is located in the passenger compartment; at the lower edge of instrument panel; near the steering column.
4. Turn the ignition switch on and access the "Read Fault" screen.
5. Record all the DTC's and "freeze frame" information shown on the appropriate scan tool.
6. To erase DTC's, use the "Erase Trouble Code" data screen on the appropriate scan tool. Do not erase any DTC's until problems have been investigated and repairs have been performed.

TASK MANAGER

The PCM is responsible for efficiently coordinating the operation of all the emissions-related components. The PCM is also responsible for determining if the diagnostic systems are operating properly. The software designed to carry out these responsibilities is call the 'Task Manager'.

TRIP DEFINITION

The term "Trip" has different meanings depending on what the circumstances are. If the MIL (Malfunction Indicator Lamp) is OFF, a Trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed in the same drive cycle.

When any Emission DTC is set, the MIL on the dash is turned ON. When the MIL is ON, it takes 3 good trips to turn the MIL OFF. In this case, it depends on what type of DTC is set to know what a "Trip" is.

For the Fuel Monitor or Misfire Monitor (continuous monitor), the vehicle must be operated in the "Similar Condition Window" for a specified amount of time to be considered a Good Trip.

If a Non-Continuous OBDII Monitor fails twice in a row and turns ON the MIL, re-running that monitor which previously failed, on the next start-up and passing the monitor, is considered to be a Good Trip. These will include the following

1. Oxygen Sensor
2. Catalyst Monitor
3. Purge Flow Monitor
4. Leak Detection Pump Monitor (if equipped)
5. EGR Monitor (if equipped)
6. Oxygen Sensor Heater Monitor

If any other Emission DTC is set (not an OBDII Monitor), a Good Trip is considered to be when the Oxygen Sensor Monitor and Catalyst Monitor have been completed; or 2 Minutes of engine run time if the Oxygen Sensor Monitor or Catalyst Monitor have been stopped from running.

It can take up to 2 Failures in a row to turn on the MIL. After the MIL is ON, it takes 3 Good Trips to turn the MIL OFF. After the MIL is OFF, the PCM will self-erase the DTC after 40 Warm-up cycles. A Warm-up cycle is counted when the ECT (Engine Coolant Temperature Sensor) has crossed 71°C (160°F) and has risen by at least 4°C (40°F) since the engine has been started.

The Task Manager determines which tests happen when and which functions occur when. Many of the diagnostic steps required by OBD II must be performed under specific operating conditions. The Task Manager software organizes and prioritizes the diagnostic procedures. The job of the Task Manager is to determine if conditions are appropriate for tests to be run, monitor the parameters for a trip for each test, and record the results of the test. Following are the responsibilities of the Task Manager software

1. Test Sequence
2. MIL Illumination
3. Diagnostic Trouble Codes (DTCs)
4. Trip Indicator
5. Freeze Frame Data Storage
6. Similar Conditions Window

Test Sequence

In many instances, emissions systems must fail diagnostic tests more than once before the PCM illuminates the MIL. These tests are know as 'two trip monitors.' Other tests that turn the MIL lamp on after a single failure are known as 'one trip monitors.' A trip is defined as 'start the vehicle and operate it to meet the criteria necessary to run the given monitor.'

Many of the diagnostic tests must be performed under certain operating conditions. However, there are times when tests cannot be run because another test is in progress (conflict), another test has failed (pending) or the Task Manager has set a fault that may cause a failure of the test (suspend).

1. Pending Under some situations the Task Manager will not run a monitor if the MIL is illuminated and a fault is stored from another monitor. In these situations, the Task Manager postpones monitors pending resolution of the original fault. The Task Manager does not run the test until the problem is remedied. For example, when the MIL is illuminated for an Oxygen Sensor fault, the Task Manager does not run the Catalyst Monitor until the Oxygen Sensor fault is remedied. Since the Catalyst Monitor is based on signals from the Oxygen Sensor, running the test would produce inaccurate results.
2. Conflict There are situations when the Task Manager does not run a test if another monitor is in progress. In these situations, the effects of another monitor running could result in an erroneous failure. If this conflict is present, the monitor is not run until the conflicting condition passes. Most likely the monitor will run later after the conflicting monitor has passed. For example, if the Fuel System Monitor is in progress, the Task Manager does not run the EGR Monitor. Since both tests monitor changes in air/fuel ratio and adaptive fuel compensation, the monitors will conflict with each other.
3. Suspend Occasionally the Task Manager may not allow a two trip fault to mature. The Task Manager will suspend the maturing of a fault if a condition exists that may induce an erroneous failure. This prevents illuminating the MIL for the wrong fault and allows more precis diagnosis. For example, if the PCM is storing a one trip fault for the Oxygen Sensor and the EGR monitor, the Task Manager may still run the EGR Monitor but will suspend the results until the Oxygen Sensor Monitor either passes or fails. At that point the Task Manager can determine if the EGR system is actually failing or if an Oxygen Sensor is failing.

MIL Illumination

The PCM Task Manager carries out the illumination of the MIL. The Task Manager triggers MIL illumination upon test failure, depending on monitor failure criteria.

The Task Manager Screen shows both a Requested MIL state and an Actual MIL state. When the MIL is illuminated upon completion of a test for a third trip, the Requested MIL state changes to OFF. However, the MIL remains illuminated until the next key cycle. (On some vehicles, the MIL will actually turn OFF during the third key cycle) During the key cycle for the third good trip, the Requested MIL state is OFF, while the Actual MIL state is ON. After the next key cycle, the MIL is not illuminated and both MIL states read OFF.

Diagnostic Trouble Codes (DTCs)

With OBD II, different DTC faults have different priorities according to regulations. As a result, the priorities determine MIL illumination and DTC erasure. DTCs are entered according to individual priority. DTCs with a higher priority overwrite lower priority DTCs.

Priorities

1. Priority 0 -Non-emissions related trouble codes
2. Priority 1 - One trip failure of a two trip fault for non-fuel system and non-misfire.
3. Priority 2 - One trip failure of a two trip fault for fuel system (rich/lean) or misfire.
4. Priority 3 - Two trip failure for a non-fuel system and non-misfire or matured one trip comprehensive component fault.
5. Priority 4 - Two trip failure or matured fault for fuel system (rich/lean) and misfire or one trip catalyst damaging misfire.

Non-emissions related failures have no priority. One trip failures of two trip faults have low priority. Two trip failures or matured faults have higher priority. One and two trip failures of fuel system and misfire monitor take precedence over non-fuel system and non-misfire failures.

DTC Self Erasure

With one trip components or systems, the MIL is illuminated upon test failure and DTCs are stored.

Two trip monitors are components requiring failure in two consecutive trips for MIL illumination. Upon failure of the first test, the Task Manager enters a maturing code. If the component fails the test for a second time the code matures and a DTC is set.

After three good trips the MIL is extinguished and the Task Manager automatically switches the trip counter to a warm-up cycle counter. DTCs are automatically erased following 40 warm-up cycles if the component does not fail again.

For misfire and fuel system monitors, the component must pass the test under a Similar Conditions Window in order to record a good trip. A Similar Conditions Window is when engine RPM is within ±375 RPM and load is within ±10% of when the fault occurred.

Note. It is important to understand that a component does not have to fail under a similar window of operation to mature. It must pass the test under a Similar Conditions Window when it failed to record a Good Trip for DTC erasure for misfire and fuel system monitors.

DTCs can be erased anytime with a diagnostic scan tool. Erasing the DTC with the scan tool erases all OBD II information. The scan tool automatically displays a warning that erasing the DTC will also erase all OBD II monitor data. This includes all counter information for warm-up cycles, trips and Freeze Frame.

Trip Indicator

The Trip is essential for running monitors and extinguishing the MIL. In OBD II terms, a trip is a set of vehicle operating conditions that must be met for a specific monitor to run. All trips begin with a key cycle.

Good Trip

The Good Trip counters are as follows

1. Specific Good Trip
2. Fuel System Good Trip
3. Misfire Good Trip
4. Alternate Good Trip (appears as a Global Good Trip on a scan tool) Comprehensive Components Major Monitor
5. Warm-Up Cycles

Specific Good Trip

The term Good Trip has different meanings depending on the circumstances

1. If the MIL is OFF, a trip is defined as when the Oxygen Sensor Monitor and the Catalyst Monitor have been completed in the same drive cycle.
2. If the MIL is ON and a DTC was set by the Fuel Monitor or Misfire Monitor (both continuous monitors), the vehicle must be operated in the Similar Condition Window for a specified amount of time.
3. If the MIL is ON and a DTC was set by a Task Manager commanded once-per-trip monitor (such as the Oxygen Sensor Monitor, Catalyst Monitor, Purge Flow Monitor, Leak Detection Pump Monitor, EGR Monitor or Oxygen Sensor Heater Monitor), a good trip is when the monitor is passed on the next start-up.
4. If the MIL is ON and any other emissions DTC was set (not an OBD II monitor), a good trip occurs when the Oxygen Sensor Monitor and Catalyst Monitor have been completed, or two minutes of engine run time if the Oxygen Sensor Monitor and Catalyst Monitor have been stopped from running.

Fuel System Good Trip

To count a good trip (three required) and turn off the MIL, the following conditions must occur

1. Engine in closed loop
2. Operating in Similar Conditions Window
3. Short Term multiplied by Long Term less than threshold
4. Less than threshold for a predetermined time

If all of the previous criteria are met, the PCM will count a good trip (three required) and turn off the MIL.

Misfire Good Trip

If the following conditions are met the PCM will count one good trip (three required) in order to turn off the MIL

1. Operating in Similar Condition Window
2. 1000 engine revolutions with no misfire

Warm-Up Cycles

Once the MIL has been extinguished by the Good Trip Counter, the PCM automatically switches to a Warm-Up Cycle Counter that can be viewed on a diagnostic scan tool. Warm-Up Cycles are used to erase DTCs and Freeze Frames. Forty Warm-Up cycles must occur in order for the PCM to self-erase a DTC and Freeze Frame. A Warm-Up Cycle is defined as follows

1. Engine coolant temperature must start below and rise above 71°C (160° F)
2. Engine coolant temperature must rise by 4°C (40° F)
3. No further faults occur

Freeze Frame Data Storage

Once a failure occurs, the Task Manager records several engine operating conditions and stores it in a Freeze Frame. The Freeze Frame is considered one frame of information taken by an on-board data recorder. When a fault occurs, the PCM stores the input data from various sensors so that technicians can determine under what vehicle operating conditions the failure occurred.

The data stored in Freeze Frame is usually recorded when a system fails the first time for two trip faults. Freeze Frame data will only be overwritten by a different fault with a higher priority.

Similar Conditions Window

The Similar Conditions Window displays information about engine operation during a monitor. Absolute MAP (engine load) and Engine RPM are stored in this window when a failure occurs. There are two different Similar conditions Windows: Fuel System and Misfire.

FUEL SYSTEM

1. Fuel System Similar Conditions Window - An indicator that 'Absolute MAP When Fuel Sys Fail' and 'RPM When Fuel Sys Failed' are all in the same range when the failure occurred. Indicated by switching from 'NO' to 'YES'.
2. Absolute MAP When Fuel Sys Fail - The stored MAP reading at the time of failure. Informs the user at what engine load the failure occurred.
3. Absolute MAP - A live reading of engine load to aid the user in accessing the Similar Conditions Window.
4. RPM When Fuel Sys Fail - The stored RPM reading at the time of failure. Informs the user at what engine RPM the failure occurred.
5. Engine RPM - A live reading of engine RPM to aid the user in accessing the Similar Conditions Window.
6. Adaptive Memory Factor - The PCM utilizes both Short Term Compensation and Long Term Adaptive to calculate the Adaptive Memory Factor for total fuel correction.
7. Upstream O2S Volts - A live reading of the Oxygen Sensor to indicate its performance. For example, stuck lean, stuck rich, etc.
8. SCW Time in Window (Similar Conditions Window Time in Window) - A timer used by the PCM that indicates that, after all Similar Conditions have been met, if there has been enough good engine running time in the SCW without failure detected. This timer is used to increment a Good Trip.
9. Fuel System Good Trip Counter - A Trip Counter used to turn OFF the MIL for Fuel System DTCs. To increment a Fuel System Good Trip, the engine must be in the Similar Conditions Window, Adaptive Memory Factor must be less than calibrated threshold and the Adaptive Memory Factor must stay below that threshold for a calibrated amount of time.
10. Test Done This Trip - Indicates that the monitor has already been run and completed during the current trip.

MISFIRE

1. Same Misfire Warm-Up State - Indicates if the misfire occurred when the engine was warmed up (above 71°C (160° F).
2. In Similar Misfire Window - An indicator that 'Absolute MAP When Misfire Occurred' and 'RPM When Misfire Occurred' are all in the same range when the failure occurred. Indicated by switching from 'NO' to 'YES'.
3. Absolute MAP When Misfire Occurred - The stored MAP reading at the time of failure. Informs the user at what engine load the failure occurred.
4. Absolute MAP - A live reading of engine load to aid the user in accessing the Similar Conditions Window.
5. RPM When Misfire Occurred - The stored RPM reading at the time of failure. Informs the user at what engine RPM the failure occurred.
6. Engine RPM - A live reading of engine RPM to aid the user in accessing the Similar Conditions Window.
7. Adaptive Memory Factor - The PCM utilizes both Short Term Compensation and Long Term Adaptive to calculate the Adaptive Memory Factor for total fuel correction.
8. 200 Rev Counter - Counts 0-100 720 degree cycles.
9. SCW Cat 200 Rev Counter - Counts when in similar conditions.
10. SCW FTP 1000 Rev Counter - Counts 0-4 when in similar conditions.
11. Misfire Good Trip Counter - Counts up to three to turn OFF the MIL.
12. Misfire Data - Data collected during test.
13. Test Done This Trip - Indicates YES when the test is done.

NON-MONITORED CIRCUITS

The PCM does not monitor the following circuits, systems and conditions that could have malfunctions causing driveability problems. The PCM might not store diagnostic trouble codes for these conditions. However, problems with these systems may cause the PCM to store diagnostic trouble codes for other systems or components. EXAMPLE: a fuel pressure problem will not register a fault directly, but could cause a rich/lean condition or misfire. This could cause the PCM to store an oxygen sensor or misfire diagnostic trouble code

FUEL PRESSURE

The fuel pressure regulator controls fuel system pressure. The PCM cannot detect a clogged fuel pump inlet filter, clogged in-line fuel filter, or a pinched fuel supply or return line. However, these could result in a rich or lean condition causing the PCM to store an oxygen sensor or fuel system diagnostic trouble code.

SECONDARY IGNITION CIRCUIT

The PCM cannot detect an inoperative ignition coil, fouled or worn spark plugs, ignition cross firing, or open spark plug cables.

CYLINDER COMPRESSION

The PCM cannot detect uneven, low, or high engine cylinder compression.

EXHAUST SYSTEM

The PCM cannot detect a plugged, restricted or leaking exhaust system, although it may set a fuel system fault.

FUEL INJECTOR MECHANICAL MALFUNCTIONS

The PCM cannot determine if a fuel injector is clogged, the needle is sticking or if the wrong injector is installed. However, these could result in a rich or lean condition causing the PCM to store a diagnostic trouble code for either misfire, an oxygen sensor, or the fuel system.

EXCESSIVE OIL CONSUMPTION

Although the PCM monitors engine exhaust oxygen content when the system is in closed loop, it cannot determine excessive oil consumption.

THROTTLE BODY AIR FLOW

The PCM cannot detect a clogged or restricted air cleaner inlet or filter element.

VACUUM ASSIST

The PCM cannot detect leaks or restrictions in the vacuum circuits of vacuum assisted engine control system devices. However, these could cause the PCM to store a MAP sensor diagnostic trouble code and cause a high idle condition.

PCM SYSTEM GROUND

The PCM cannot determine a poor system ground. However, one or more diagnostic trouble codes may be generated as a result of this condition. The module should be mounted to the body at all times, also during diagnostic.

PCM CONNECTOR ENGAGEMENT

The PCM may not be able to determine spread or damaged connector pins. However, it might store diagnostic trouble codes as a result of spread connector pins.

SPECIFICATIONS

TORQUE SPECIFICATIONS

Scheme 3

The electronic EGR valve and solenoid assembly (1) is attached to the rear of the left cylinder head.

Scheme 4

Scheme 5

1. Use a diagnostic scan tool to record any DTC's (Diagnostic Trouble Codes).
2. Disconnect and isolate the negative battery cable. An exhaust gas routing tube (1) connects the EGR valve (4) to the intake manifold.
3. Remove two tube mounting bolts (2).
4. Remove tube (1) from solenoid (4). Slip opposite end of tube (6) from intake manifold.
5. Remove gasket (3) located between EGR valve solenoid and tube flange.
6. Disconnect electrical connector (3) at solenoid (1).
7. Remove two EGR valve solenoid mounting bolts (2).
8. Remove solenoid (1) from engine.
9. Remove and discard gasket (1) located under EGR solenoid.

INSTALLATION

1. Clean gasket area (1) at rear of left cylinder head where it joins base of EGR valve.
2. Clean EGR tube where it joins EGR valve.
3. Position new gasket between EGR valve and cylinder head.
4. Position EGR valve to cylinder head. Install and tighten two bolts (2). Torque to 9 N.m (80 in. lbs.).
5. Position new gasket (3) between EGR tube flange and EGR valve assembly.
6. Position EGR tube (1) to side of EGR valve. Position end of tube (6) into intake manifold. Install two bolts (2). Torque to 11 N.m (8.5 ft. lbs.).
7. Connect electrical connector (3) to top of EGR valve solenoid (1).
8. Connect negative battery cable.
9. Using a diagnostic scan tool, erase any previously recorded DTC's (Diagnostic Trouble Codes).

Scheme 6

The electronic EGR valve and solenoid assembly (4) is attached to the rear of the left cylinder head. An exhaust gas routing tube (3) connects the EGR valve to the intake manifold.

Scheme 7

1. Use a diagnostic scan tool to record any DTC's (Diagnostic Trouble Codes).
2. Disconnect and isolate the negative battery cable.
3. Remove plastic windshield cowl panel.
4. Remove windshield wiper motor.
5. Remove electrical connector (5) at top of EGR valve solenoid.
6. Remove tube mounting bolt (1) at intake manifold.
7. Remove two bolts (4) connecting EGR tube (1) to valve assembly.
8. Remove gasket located between EGR tube flange and EGR valve assembly.
9. Remove two EGR valve mounting bolts (5).
10. Separate valve assembly (3) from engine.
11. Remove and discard metal gasket located between cylinder head and valve assembly.

1. Clean area at rear of left cylinder head where it joins base of EGR valve.
2. Clean EGR tube where it joins EGR valve.
3. Position new gasket between EGR valve and cylinder head.
4. Position EGR valve to cylinder head. Install and tighten two bolts (5). Torque to 9 N.m (80 in. lbs.).
5. Position new gasket between EGR tube flange and EGR valve assembly.
6. Position EGR tube (1) to side of EGR valve and into intake manifold. Install two bolts (4) finger tight (temporarily).
7. Install EGR tube flange bolt (1) at intake manifold. Torque to 11 N.m (8.5 ft. lbs.).
8. Connect electrical connector (5) to top of EGR valve solenoid (4).
9. Do a final tightening of two EGR tube bolts (4). Torque to 11 N.m (8.5 ft. lbs.).
10. Install windshield wiper motor.
11. Install plastic windshield cowl panel.
12. Connect negative battery cable.
13. Using a diagnostic scan tool, erase any previously recorded DTC's (Diagnostic Trouble Codes).

Scheme 8

The electronic EGR valve and solenoid assembly (3) is attached to the front of the right cylinder head (1). An exhaust gas routing tube connects the EGR valve to the intake manifold.

Scheme 9

1. Use a diagnostic scan tool to record any DTC's (Diagnostic Trouble Codes).
2. Disconnect and isolate the negative battery cable.
3. Remove air resonator box above EGR valve/solenoid.
4. Remove accessory serpentine drive belt.
5. Remove generator mounting bolts.
6. Reposition generator to gain access to EGR valve-to-cylinder head mounting bolts. No need to remove generator wiring from generator.
7. Disconnect electrical connector (1) from EGR solenoid (2).
8. Remove two bolts (3) connecting EGR tube (4) to valve assembly.
9. Remove gasket located between EGR tube flange and EGR valve assembly.
10. Remove two mounting bolts (2).
11. Separate valve assembly (3) from cylinder head (1).
12. Remove and discard metal gasket located between cylinder head and valve assembly.

1. Position a new metal gasket between cylinder head (1) and valve assembly (3).
2. Install two mounting bolts (2) and tighten to 20 ft. lbs. (27 N.m).
3. Clean EGR tube where it joins EGR valve.
4. Position new gasket between EGR tube flange and EGR valve assembly.
5. Install two bolts (3) connecting EGR tube (4) to valve assembly (2). Tighten bolts to 20 ft. lbs. (27 N.m).
6. Connect electrical connector (1) to EGR solenoid (2).
7. Position generator to generator mounting bracket.
8. Install generator mounting bolts. Tighten generator mounting bolts to 30 ft. lbs. (41 N.m). CAUTION: Never force a belt over a pulley rim using a screwdriver. The synthetic fiber of the belt can be damaged. CAUTION: When installing a serpentine accessory drive belt, the belt MUST be routed correctly. The water pump may be rotating in the wrong direction if the belt is installed incorrectly, causing the engine to overheat. Refer to belt routing label in engine compartment, or refer to Belt Schematics in 7, Cooling System.
9. Install accessory serpentine drive belt.
10. Install air resonator box above EGR valve/solenoid.
11. Connect negative battery cable to battery.
12. Using a diagnostic scan tool, erase any previously recorded DTC's (Diagnostic Trouble Codes).

Scheme 10

1. Disconnect the negative battery cable.
2. Remove engine cover. Refer to «REMOVAL»(/jeep/grand-cherokee/wk-2004-2010/remont/mechanical/#37l-engine-service-information__removal) .
3. Disconnect the EGR valve harness connector (1).
4. Remove EGR valve retaining bolts (2) and valve (3), discard the gasket.

1. Clean EGR valve sealing surfaces.
2. Lubricate the seal and install the EGR valve (3) in intake manifold. Tighten EGR valve retaining bolts (2) to 9 N.m (80 lbs.in).
3. Connect the EGR valve harness connector (1).
4. Install engine cover.
5. Connect the negative battery cable.

DESCRIPTION

The EGR back pressure sensor is located in the exhaust stream next to the EGR valve. The sensor determines the exhaust pressure before the catalytic converter. The ECM uses the EGR back pressure sensor for engine protection and exhaust gas turbocharger protection.

To prevent damage to the turbocharger from overheating and/or overspeeding, the ECM monitors the exhaust pressure upstream of the turbocharger. At high exhaust backpressure, the speed of the turbocharger drops and consequently the boost pressure drops. The ECM adjusts the guide vanes in the turbocharger to regulate the boost pressure.

OPERATION

The exhaust gas effects a sensor membrane that acts against a potentiometer internal to the sensor. The potentiometer changes the resistance value and thus influences the signal voltage of the sensor.

Scheme 11

1. Disconnect the negative battery cable.
2. Remove the engine cover.
3. Disconnect the EGR Backpressure Sensor harness connector (1).
4. Remove the EGR Backpressure Sensor (2).

1. Install the EGR back pressure sensor (2).
2. Connect the EGR back pressure sensor harness connector (1).
3. Install the engine cover.
4. Connect the negative battery cable.

FUEL RAIL

The Exhaust Gas Recirculation (EGR) Air Flow Valve Actuator and Resonator are located in the air intake tube between the turbocharger intercooler and the intake manifold. The EGR Air Flow Valve is controlled by the ECM. Refer to the appropriate engine diagnostic procedures for DTCs related to the EGR Airflow Valve Actuator.

The Exhaust Gas Recirculation (EGR) throttle valve adjusts the flow of fresh air into the engine during EGR operation. A signal from the Engine Control Module (ECM) controls the operation of the EGR throttle valve. The position at which the ECM will set the valve depends on the blended quantity of exhaust gas that needs to be recirculated into the engine in order for the exhaust gas to remain with the target emission level, which the ECM calculates based on input received from the oxygen sensors. When not actuated, the EGR throttle valve is in the open position.

3.0L DIESEL

1. Perform the Fuel Pressure Release procedure.
2. Disconnect the Negative Battery Cable.
3. Remove the Engine Cover.
4. Remove the Air Filter Housing and Intake Tube.
5. Remove the Engine Cover Support Brace.
6. Remove the Turbocharger Intercooler Tube.
7. Remove the Lower Turbocharger Intercooler Flex Hose.
8. Position the Vacuum Pump aside.
9. Disconnect the EGR Airflow Valve and IAT harness connectors.
10. Disconnect the EGR Tube from the Charge Air Crossover Manifold, located upstream of the Intake Manifolds.
11. Remove the IAT Sensor Housing Bracket bolts and Bracket.
12. Remove the Fuel Line Support.
13. Remove the IAT Sensor Housing retaining bolts and remove the IAT Sensor Housing.
14. Remove the EGR Airflow Valve bolts.
15. Remove the EGR Airflow Valve.

1. Install the EGR Airflow Valve.
2. Install the EGR Airflow Valve bolts.
3. Install the IAT Sensor Housing and the IAT Sensor Housing retaining bolts.
4. Install the Fuel Line Support.
5. Install the IAT Sensor Housing Bracket and bolts.
6. Install the EGR Tube to the Charge Air Crossover Manifold, located upstream of the Intake Manifolds.
7. Reconnect the EGR Airflow Valve and IAT harness connectors.
8. Install the Vacuum Pump.
9. Install the Lower Turbocharger Intercooler Flex Hose.
10. Install the Turbocharger Intercooler Tube.
11. Install the Engine Cover Support Brace.
12. Install the Air Filter Housing and Intake Tube.
13. Install the Engine Cover.
14. Reconnect the Negative Battery Cable.

Scheme 12

Scheme 13

1. Disconnect the negative battery cable.
2. Remove the left intake manifold. Refer to «REMOVAL»(/jeep/grand-cherokee/wk-2004-2010/remont/mechanical/#37l-engine-service-information) .
3. Remove the 2 upper EGR cooler bolts (1).
4. Remove the 4 front EGR cooler retaining bolts (1) and EGR cooler (2).

1. Clean EGR cooler sealing surfaces.
2. Install the EGR cooler (2) and the 4 front EGR cooler retaining bolts (1).
3. Install the 2 upper EGR cooler bolts (1).
4. Install the left intake manifold. Refer to «INSTALLATION»(/jeep/grand-cherokee/wk-2004-2010/remont/mechanical/#37l-engine-service-information) .
5. Install engine cover.
6. Connect the negative battery cable.

EVAPORATIVE EMISSIONS-HIGH AND LOW LIMITS

The PCM compares input signal voltages from each input device with established high and low limits for the device. If the input voltage is not within limits and other criteria are met, the PCM stores a diagnostic trouble code in memory. Other diagnostic trouble code criteria might include engine RPM limits or input voltages from other sensors or switches that must be present before verifying a diagnostic trouble code condition.

OBD II MONITOR RUN PROCESS

The following procedure has been established to assist DaimlerChrysler Dealer Technicians in the field with enabling and running OBD II Monitors. The order listed in the following procedure is intended to allow the technician to effectively complete each monitor and to set the CARB Readiness Status in the least time possible.

Note. Once the monitor run process has begun, do not turn off the ignition. By turning the ignition key off, monitor enabling conditions will be lost. NVLD Monitor runs after key off. By performing a Battery Disconnect, or Selecting Erase DTCs, the CARB Readiness and all additional OBD II information will be cleared.

Monitor Preliminary Checks

1. Plug a scan tool into the vehicle's Data Link Connector (DLC).
2. Turn the ignition, KEY ON - ENGINE OFF. Watch for MIL lamp illumination during the bulb check. MIL lamp must have illuminated, if not, repair MIL lamp.
3. Using a scan tool check for Powertrain related DTCs. Verify that No Emissions Related DTCs are Present. * If an Emissions DTC is Present, the OBD II Monitors may not run and the CARB Readiness will not update. The Emissions related DTC, will need to be repaired, then cleared. By clearing DTCs, the OBD Monitors will need to be run and completed to set the CARB Readiness Status.

Using the scan tool check the CARB Readiness Status.

Do all the CARB Readiness Status Locations read YES?.

1. *YES, then all monitors have been completed and this vehicle is ready to be I/M or Emission Tested.
2. *NO, then the following procedure needs to be followed to run/complete all available monitors.

Note. Only the monitors, which are not YES in the CARB Readiness Status, need to be completed. Specific criteria need to be met for each monitor. The most efficient order to run the monitors has been outlined below, including suggestions to aid the process.

Evaporative Emission System Leak Detection with Purge Monitor

This monitor requires a cool down cycle, usually an overnight soak for at least 8 hours without the engine running. The ambient temperature must decrease overnight - parking the vehicle outside is advised. To run this test the fuel level must be between 15-85% full. For the monitor run conditions select the EVAP MON PRE-TEST in the scan tool, OBD II Monitors Menu. The Purge monitor will run if the small leak test reports a pass. Criteria for EVAP monitor

1. Engine off time greater than @ one hour.
2. Fuel Level between 15% and 85 %.
3. Start Up ECT and IAT within 10° C (18° F).
4. Vehicle started and run until Purge Monitor reports a result.

Note. If the vehicle does not report a result and the conditions where correct. It may take up to two weeks to fail the small leak monitor. DO NOT use this test to attempt to determine a fault. Use the appropriate service information procedure for finding a small leak. If there are no faults and the conditions are correct this test will run and report a pass. Note the Small leak test can find leaks less than 10 thousands of an inch. If a small leak is present it takes approximately one week of normal driving to report a failure.

Catalyst / O2 Monitor

With NGC, Catalyst and O2 Monitor information are acquired and processed at the same time. Most vehicles will need to be driven at highway speed (< 50 mph) for a few minutes. Some vehicles run the monitor at idle in drive. If the vehicle is equipped with a manual transmission, using 4th gear may assist in meeting the monitor running criteria. For the monitor run conditions, select the BANK 1 CAT MON PRE-TEST in the scan tool, OBD II Monitors Menu.

EGR Monitor

The EGR monitor now runs in a closed throttle decel or at idle on a warm vehicle. However, it is necessary to maintain the TPS, Map and RPM ranges to allow the monitor to complete itself. For the monitor run conditions, select the EGR PRE-TEST in the scan tool, OBD II Monitors Menu.

O2 Sensor Heater Monitor

This monitor is now continuously running once the heaters are energized. Pass information will be processed at power down. For the monitor run conditions, select the O2S HEATER MON PRE-TEST in the scan tool, OBD II Monitors Menu.

Misfire Monitor

The NGC Misfire Monitor is a continuous two-trip monitor. The monitor uses two different tests/counters

Note. The Adaptive Numerator must be learned before the PCM will run the Misfire Monitor. The PCM updates the Adaptive Numerator at every key-ON, and is relearned after battery disconnect. The Misfire Monitor will not run until the Adaptive Numerator has updated since the last battery disconnect. If the Adaptive Numerator is equal to the default value then the PCM knows that the Adaptive Numerator has not been learned and does not permit the Misfire Monitor to run. If the Adaptive Numerator exceeds a calibrated percentage, the PCM sets a DTC for CKP NOT LEARNED and illuminates the MIL.

1. 200 Revolution Counter - Looks for misfire that can cause immediate catalyst damage.
2. 1000 Revolution Counter - Looks for misfire that can cause emissions to increase 1.5 times the Federal Test Procedure (FTP) standards. This test must also identify misfire percentages that might cause a "durability demonstration vehicle" to fail an Inspection and Maintenance Program tailpipe emissions test.

OBD II MONITOR OPERATION

TORQUE CHART

TORQUE SPECIFICATIONS

Scheme 14

The duty cycle EVAP canister purge solenoid (2) is located in the engine compartment attached to a bracket.

EVAPORATIVE SYSTEM AND PURGE SOLENOID

The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.

The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM energizes and de-energizes the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time the solenoid energizes. The PCM adjusts solenoid pulse width based on engine operating condition.

The duty cycle EVAP canister purge solenoid (1) is located in the engine compartment attached to a bracket.

1. Disconnect electrical wiring connector (2) at solenoid.
2. Disconnect vacuum lines at solenoid.
3. Remove solenoid from mounting bracket by lifting straight up.

1. Install solenoid assembly (1) to mounting bracket.
2. Connect vacuum harness.
3. Connect electrical connector (2).

The plastic fuel tank filler tube cap is threaded onto the end of the fuel fill tube. Certain models are equipped with a 1/4 turn cap.

The loss of any fuel or vapor out of fuel filler tube is prevented by the use of a pressure-vacuum fuel fill cap. Relief valves inside the cap will release fuel tank pressure at predetermined pressures. Fuel tank vacuum will also be released at predetermined values. This cap must be replaced by a similar unit if replacement is necessary. This is in order for the system to remain effective.

REMOVAL

If replacement of the 1/4 turn fuel tank filler tube cap is necessary, it must be replaced with an identical cap to be sure of correct system operation.

ON-BOARD REFUELING VAPOR RECOVERY

The ORVR (On-Board Refueling Vapor Recovery) system consists of a unique fuel tank, flow management valve, fluid control valve, one-way check valve and vapor canister.

The ORVR (On-Board Refueling Vapor Recovery) system is used to remove excess fuel tank vapors. This is done while the vehicle is being refueled.

Fuel flowing into the fuel filler tube (approx. 1" I.D.) creates an aspiration effect drawing air into the fuel fill tube. During refueling, the fuel tank is vented to the EVAP canister to capture escaping vapors. With air flowing into the filler tube, there are no fuel vapors escaping to the atmosphere. Once the refueling vapors are captured by the EVAP canister, the vehicle's computer controlled purge system draws vapor out of the canister for the engine to burn. The vapor flow is metered by the purge solenoid so that there is no, or minimal impact on driveability or tailpipe emissions.

As fuel starts to flow through the fuel fill tube, it opens the normally closed check valve and enters the fuel tank. Vapor or air is expelled from the tank through the control valve and on to the vapor canister. Vapor is absorbed in the EVAP canister until vapor flow in the lines stops. This stoppage occurs following fuel shut-off, or by having the fuel level in the tank rise high enough to close the control valve. This control valve contains a float that rises to seal the large diameter vent path to the EVAP canister. At this point in the refueling process, fuel tank pressure increases, the check valve closes (preventing liquid fuel from spiting back at the operator), and fuel then rises up the fuel filler tube to shut off the dispensing nozzle.

Scheme 15

The NVLD ( N atural V acuum L eak D etection) pump (2) is attached to the EVAP canister (3). This assembly is located in the left-rear quarter-panel behind the left-rear tire. Refer to NVLD Removal / Installation for additional information.

NATURAL VACUUM LEAK DETECTION PUMP

The N atural V acuum L eak D etection (NVLD) system is the next generation evaporative leak detection system that will first be used on vehicles equipped with the Next Generation Controller (NGC). This new system replaces the leak detection pump as the method of evaporative system leak detection. This is to detect a leak equivalent to a 0.020" (0.5 mm) hole. This system has the capability to detect holes of this size very dependably.

The basic leak detection theory employed with NVLD is the "Gas Law". This is to say that the pressure in a sealed vessel will change if the temperature of the gas in the vessel changes. The vessel will only see this effect if it is indeed sealed. Even small leaks will allow the pressure in the vessel to come to equilibrium with the ambient pressure. In addition to the detection of very small leaks, this system has the capability of detecting medium as well as large evaporative system leaks.

A vent valve seals the canister vent during engine off conditions. If the vapor system has a leak of less than the failure threshold, the evaporative system will be pulled into a vacuum, either due to the cool down from operating temperature or diurnal ambient temperature cycling. The diurnal effect is considered one of the primary contributors to the leak determination by this diagnostic. When the vacuum in the system exceeds about 1" H2O (0.25 kPa), a vacuum switch closes. The switch closure sends a signal to the NGC. The NGC, via appropriate logic strategies, utilizes the switch signal, or lack thereof, to make a determination of whether a leak is present.

The NVLD device is designed with a normally open vacuum switch, a normally closed solenoid, and a seal, which is actuated by both the solenoid and a diaphragm. The NVLD is located on the atmospheric vent side of the canister. The NVLD assembly may be mounted on top of the canister outlet, or in-line between the canister and atmospheric vent filter. The normally open vacuum switch will close with about 1" H2O (0.25 kPa) vacuum in the evaporative system. The diaphragm actuates the switch. This is above the opening point of the fuel inlet check valve in the fill tube so cap off leaks can be detected. Submerged fill systems must have recirculation lines that do not have the in-line normally closed check valve that protects the system from failed nozzle liquid ingestion, in order to detect cap off conditions.

The normally closed valve in the NVLD is intended to maintain the seal on the evaporative system during the engine off condition. If vacuum in the evaporative system exceeds 3" to 6" H2O (0.75 to 1.5 kPa), the valve will be pulled off the seat, opening the seal. This will protect the system from excessive vacuum as well as allowing sufficient purge flow in the event that the solenoid was to become inoperative.

The solenoid actuates the valve to unseal the canister vent while the engine is running. It also will be used to close the vent during the medium and large leak tests and during the purge flow check. This solenoid requires an initial 1.5 amps of current to pull the valve open, but after 100 milliseconds, will be duty cycled down to an average of about 150 mA for the remainder of the drive cycle.

Another feature in the device is a diaphragm that will open the seal in the NVLD with pressure in the evaporative system. The device will "blow off" at about 0.5" H2O (0.12 kPa) pressure to permit the venting of vapors during refueling. An added benefit to this is that it will also allow the tank to "breathe" during increasing temperatures, thus limiting the pressure in the tank to this low level. This is beneficial because the induced vacuum during a subsequent declining temperature will achieve the switch closed (pass threshold) sooner than if the tank had to decay from a built up pressure.

The device itself has 3 wires: Switch sense, solenoid driver and ground. It also includes a resistor to protect the switch from a short to battery or a short to ground. The NGC utilizes a high-side driver to energize and duty-cycle the solenoid.

The NVLD pump (2) is attached to the EVAP canister (3). This assembly is located in the left-rear quarter-panel behind the left-rear tire.

Scheme 16

Scheme 17

1. Raise and support vehicle.
2. Remove left-rear tire.
3. To access EVAP canister or NVLD pump, remove plastic splash shield at rear of left-rear tire.
4. Disconnect electrical connector (4) at pump.
5. Carefully remove vapor/vacuum hoses at pump.
6. Pry outward on tab (3) and rotate pump clockwise about 70 degrees for removal.
7. Remove NVLD pump o-ring (2) from EVAP canister (1).

1. Install new NVLD pump o-ring (2) to EVAP canister (1).
2. Position NVLD pump (4) into EVAP canister (1).
3. Rotate pump (4) until tab (3) aligns with notch in EVAP canister (1).
4. Carefully install vapor/vacuum lines (1) and (6) to NVLD pump and EVAP canister. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the NVLD pump, filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.
5. Connect electrical connector (4) to pump.
6. Install plastic splash shield at rear of left-rear tire.
7. Install left-rear tire.

Scheme 18

The 3.7L V-6 and 4.7L V-8 engines are equipped with a closed crankcase ventilation system. The Positive Crankcase Ventilation (PCV) valve (6) is mounted to the oil filler housing (4).

The PCV valve is sealed to the oil filler housing with an o-ring (1).

Scheme 19

Two interconnected breathers (1) threaded into the rear of each cylinder head are used with the system.

The system also includes the air cleaner housing and various tubes and hoses to connect the system components.

Scheme 20

The 5.7L V-8 engine is equipped with a closed crankcase ventilation system and a Positive Crankcase Ventilation (PCV) valve.

A PCV valve (4) mounted into the top of the intake manifold (1), located to the right / rear of the throttle body (2) is used.

Scheme 21

The PCV valve (1) is sealed to the intake manifold with two o-rings (2).

The system also consists of passages in the intake manifold, and various tubes and hoses to connect the system components.

Scheme 22

A typical enclosed crankcase ventilation system is shown in the graphic.

The PCV system operates by engine intake manifold vacuum. Filtered air is routed into the crankcase through the air cleaner hose. The metered air, along with crankcase vapors, are drawn through the PCV valve (4) and into a passage in the intake manifold. The PCV system manages crankcase pressure and meters blow by gases to the intake system, reducing engine sludge formation.

The PCV valve contains a spring loaded plunger. This plunger meters the amount of crankcase vapors routed into the combustion chamber based on intake manifold vacuum.

Scheme 23

When the engine is not operating or during an engine pop-back, the spring forces the plunger back against the seat. This will prevent vapors from flowing through the valve.

Scheme 24

During periods of high manifold vacuum, such as idle or cruising speeds, vacuum is sufficient to completely compress spring. It will then pull the plunger to the top of the valve. In this position there is minimal vapor flow through the valve.

Scheme 25

During periods of moderate manifold vacuum, the plunger is only pulled part way back from inlet. This results in maximum vapor flow through the valve.

PCV VALVE TEST - 3.7L AND 4.7L ENGINES

Scheme 26

1. Disconnect PCV line/hose (5) by disconnecting rubber connecting hose at PCV valve fitting.
2. Remove PCV valve at oil filler tube by rotating PCV valve downward until locating tabs (2) have been freed at cam lock (3). After tabs have cleared, pull valve straight out from filler tube. To prevent damage to PCV valve locating tabs, valve must be pointed downward for removal. Do not force valve from oil filler tube.
3. After valve is removed, check condition of valve o-ring (1). Also, PCV valve should rattle when shaken.
4. Reconnect PCV valve to its connecting line/hose.
5. Start engine and bring to idle speed.
6. If valve is not plugged, a hissing noise will be heard as air passes through valve. Also, a strong vacuum should be felt with a finger placed at valve inlet.
7. If vacuum is not felt at valve inlet, check line/hose for kinks or for obstruction. If necessary, clean out intake manifold fitting at rear of manifold. Do this by turning a 1/4 inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with shop air. If necessary, use a smaller drill to avoid removing any metal from the fitting.
8. Do not attempt to clean the old PCV valve.
9. Return PCV valve back to oil filler tube by placing valve locating tabs (2) into cam lock (3). Press PCV valve in and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed towards rear of vehicle.
10. Connect PCV line/hose (5) and connecting rubber hose to PCV valve.
11. Disconnect rubber hose from fresh air fitting at air cleaner resonator box. Start engine and bring to idle speed. Hold a piece of stiff paper (such as a parts tag) loosely over the opening of the disconnected rubber hose.
12. The paper should be drawn against the hose opening with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce. 1 - CRANKCASE BREATHERS (2) 2 - REAR OF ENGINE
13. If vacuum is not present, disconnect each PCV system hose at top of each crankcase breather (1). Check for obstructions or restrictions.
14. If vacuum is still not present, remove each PCV system crankcase breather's (1) from each cylinder head. Check for obstructions or restrictions. If plugged, replace breather. Tighten breather to 12 N.m (106 in. lbs.) torque. Do not attempt to clean breather. 1 - CONNECTING HOSES 2 - CHECK VALVES
15. If vacuum is still not present, disconnect each PCV system hose (1) at each fitting, and at each check valve (2). Check for obstructions or restrictions.

3.7L AND 4.7L ENGINES

The PCV valve (6) is located on the oil filler tube (4). Two locating tabs are located on the side of the valve (2). These 2 tabs fit into a cam lock (3) in the oil filler tube. An o-ring (1) seals the valve to the filler tube.

1. Disconnect PCV line/hose (5) by disconnecting rubber hose at PCV valve fitting.
2. Remove PCV valve at oil filler tube by rotating PCV valve downward (counter-clockwise) until locating tabs (2) have been freed at cam lock (3). After tabs have cleared, pull valve straight out from filler tube. To prevent damage to PCV valve locating tabs, valve must be pointed downward for removal. Do not force valve from oil filler tube.
3. After valve is removed, check condition of valve o-ring (1).

5.7L ENGINE

The PCV valve (4) is mounted into the top of the intake manifold (1). This is located to the right / rear of the throttle body (2).

1. The PCV valve is sealed to the intake manifold with 2 O-rings (2).
2. Remove PCV valve by rotating counter-clockwise 90 degrees until locating tabs (3) have been freed. After tabs have cleared, pull valve straight up from intake manifold.
3. After valve is removed, check condition of 2 valve O-rings (2).

The PCV valve is located on the oil filler tube. Two locating tabs are located on the side of the valve. These 2 tabs fit into a cam lock in the oil filler tube. An o-ring seals the valve to the filler tube.

1. Return PCV valve back to oil filler tube by placing valve locating tabs into cam lock. Press PCV valve in and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed towards rear of vehicle.
2. Connect PCV line/hose and rubber hose to PCV valve.

1. Clean out intake manifold opening.
2. Check condition of 2 o-rings on PCV valve.
3. Apply engine oil to 2 o-rings.
4. Place PCV valve into intake manifold and rotate 90 degrees clockwise for installation.

VACUUM LINES

A vacuum schematic for emission related items can be found on the vehicles VECI label. Refer to Vehicle Emission Control Information (VECI) Label for label location.

VAPOR CANISTER

The Evaporative System Vapor Canister (3) is located in the left-rear quarter-panel behind the left-rear tire.

The Evaporative System Vapor Canister is filled with granules of an activated carbon mixture. Fuel vapors entering the EVAP canister is absorbed by the charcoal granules.

Fuel tank pressure vents into the EVAP canister. Fuel vapors are temporarily held in the canister until they can be drawn into the intake manifold. The duty cycle EVAP canister purge solenoid allows the EVAP canister to be purged at predetermined times and at certain engine operating conditions.

The N atural V acuum L eak D etection (NVLD) pump (2) is attached to the Evaporative System Vapor Canister (3). This assembly is located in the left-rear quarter-panel behind the left-rear tire.

Scheme 27

1. Raise and support vehicle.
2. Remove left-rear tire.
3. To access EVAP canister or NVLD pump, remove plastic splash shield at rear of left-rear tire.
4. Disconnect electrical connector (4) at pump.
5. Carefully remove vapor/vacuum hoses (1) and (6) at pump.
6. Remove three canister bracket-to-body nuts (1) and (2).
7. Separate canister from mounting bracket by removing two canister-to-bracket nuts at front of canister (4). The opposite end of canister is equipped with two alignment pins. Remove canister from support bracket by pulling these two pins from the two rubber grommets To Separate NVLD Pump from EVAP canister
8. Pry outward on tab (3) and rotate pump clockwise about 70 degrees for removal.
9. Remove NVLD pump o-ring (2) from EVAP canister (1).

To Install NVLD Pump to EVAP canister

1. Install new NVLD pump o-ring (2) to EVAP canister (1).
2. Position NVLD pump (4) into EVAP canister (1).
3. Rotate pump (4) until tab (3) aligns with notch in EVAP canister (1). To Install EVAP canister
4. Position canister (5) into mounting bracket (4). Install and tighten two canister-to-mounting bracket nuts.
5. Position canister/pump assembly to body. Install and tighten three mounting bracket-to-body nuts.
6. Carefully install vapor/vacuum lines (1) and (6) to NVLD pump and EVAP canister. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the NVLD pump, filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.
7. Connect electrical connector (4) to pump.
8. Install plastic splash shield at rear of left-rear tire.
9. Install left-rear tire.

GLOSSARY OF TERMS

OBDII MONITOR RUN PROCESS

The following procedure has been established to assist technicians in the field with enabling and running OBD II Monitors. The order listed in the following procedure is intended to allow the technician to effectively complete each monitor and to set the CARB Readiness Status in the least time possible.

Note. Once the monitor run process has begun, do not turn off the ignition. By turning the ignition key off, monitor enabling conditions will be lost. EVAP Monitor runs after key off. By performing a Battery Disconnect, or Selecting Erase DTCs, the CARB Readiness and all additional OBD II information will be cleared.

1. Plug a scan tool into the vehicle's Data Link Connector (DLC).
2. Turn the ignition, KEY ON - ENGINE OFF. Watch for MIL lamp illumination during the bulb check. MIL lamp must have illuminated, if not, repair MIL lamp.
3. Using a scan tool check for Powertrain related DTCs. Verify that No Emissions Related DTCs are Present. If an Emissions DTC is Present, the OBD II Monitors may not run and the CARB Readiness will not update. The Emissions related DTC, will need to be repaired, then cleared. By clearing DTCs, the OBD Monitors will need to be run and completed to set the CARB Readiness Status.

Using the scan tool check the CARB Readiness Status.

Do all the CARB Readiness Status Locations read YES?

1. YES - all monitors have been completed and this vehicle is ready to be I/M or Emission Tested.
2. NO - then the following procedure needs to be followed to run/complete all available monitors.

Note. Only the monitors, which are not YES in the CARB Readiness Status, need to be completed. Specific criteria need to be met for each monitor. The most efficient order to run the monitors has been outlined below, including suggestions to aid the process.

This monitor requires a cool down cycle, usually an overnight soak for at least 8 hours without the engine running. The ambient temperature must decrease overnight - parking the vehicle outside is advised. To run this test the fuel level must be between 15-85% full. Criteria for EVAP monitor

1. Engine off time greater than one hour.
2. Fuel Level between 15% and 85%.
3. Start Up ECT and IAT within 10°C (18°F).
4. Vehicle started and run until Purge Monitor reports a result.

Note. If the vehicle does not report a result and the conditions where correct. It may take up to two weeks to fail the small leak monitor. DO NOT use this test to attempt to determine a fault. Use the appropriate service information procedure for finding a small leak. If there are no faults and the conditions are correct this test will run and report a pass. Note the Small leak test can find leaks less than 10 thousands of an inch. If a small leak is present it takes approximately one week of normal driving to report a failure.

The Catalyst and O2 Monitor information are acquired and processed at the same time. Most vehicles will need to be driven at highway speed (less than 50 mph) (73km/h) for a few minutes. Some vehicles run the monitor at idle in drive. If the vehicle is equipped with a manual transmission, using 4th gear may assist in meeting the monitor running criteria.

1. Engine RPM between 1200 to 3000.
2. Engine temperature greater than 70°C (158°F)
3. Engine run time greater than 92 seconds
4. MAP between 10 - 20 kPa (7.5 - 15 Hg)
5. Vehicle speed between 20 - 70 mph (29-103 km/h)

After the vehicle has reached the below conditions and during a throttle decel the EGR monitor will run.

1. Engine RPM between 1375 - 2500
2. Engine temperature greater than 70°C (158°F)
3. Engine run time greater than 125 seconds
4. Vehicle speed between 25 - 70 mph (37-103 km/h)

This monitor is now continuously running once the heaters are energized. Pass information will be processed at power down.

The Misfire Monitor is a continuous two-trip monitor. The monitor uses two different tests/counters

Note. The Adaptive Numerator must be learned before the PCM will run the Misfire Monitor. The PCM updates the Adaptive Numerator at every key-ON, and is relearned after battery disconnect. The Misfire Monitor will not run until the Adaptive Numerator has updated since the last battery disconnect. If the Adaptive Numerator is equal to the default value then the PCM knows that the Adaptive Numerator has not been learned and does not permit the Misfire Monitor to run. If the Adaptive Numerator exceeds a calibrated percentage, the PCM sets a DTC for CKP NOT LEARNED and illuminates the MIL.

1. 200 Revolution Counter - Looks for misfire that can cause immediate catalyst damage.
2. 1000 Revolution Counter - Looks for misfire that can cause emissions to increase 1.5 times the Federal Test Procedure (FTP) standards. This test must also identify misfire percentages that might cause a "durability demonstration vehicle" to fail an Inspection and Maintenance Program tailpipe emissions test.

See also:
• REMOVAL
• REMOVAL