Emissions Control: Overview Dodge Journey I

DESCRIPTION - MONITORED COMPONENT

There are several components that will affect vehicle emissions if they malfunction. If one of these components malfunctions the Malfunction Indicator Lamp (Check Engine) 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 as well as continuity tests (opens/shorts). 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 and 1600 RPM.

Any component that has an associated limp in will set a fault after 1 trip with the malfunction present.

Refer to the DTC INDEX for diagnostic procedures.

The following is a list of the monitored components

1. Catalyst Monitor
2. Comprehensive Components
3. EGR (if equipped)
4. Fuel Control (rich/lean)
5. Oxygen Sensor Monitor
6. Oxygen Sensor Heater Monitor
7. Purge
8. Misfire
9. ESIM (Evaporative System Integrity Monitor)

DESCRIPTION - MONITORED SYSTEMS

There are new electronic circuit monitors that check fuel, emission, engine and ignition performance. These monitors use information from various sensor circuits to indicate the overall operation of the fuel, engine, ignition and emission systems and thus the emissions performance of the vehicle.

The fuel, engine, ignition and emission systems monitors do not indicate a specific component problem. They do indicate that there is an implied problem within one of the systems and that a specific problem must be diagnosed.

If any of these monitors detect a problem affecting vehicle emissions, the Malfunction Indicator (Check Engine) Lamp will be illuminated. These monitors generate Diagnostic Trouble Codes that can be displayed with the a scan tool.

The following is a list of the system monitors

1. EGR Monitor (if equipped)
2. Misfire Monitor
3. Fuel System Monitor
4. Oxygen Sensor Monitor
5. Oxygen Sensor Heater Monitor
6. Catalyst Monitor
7. Evaporative System Leak Detection Monitor (if equipped)

Following is a description of each system monitor, and its DTC.

Refer to POWERTRAIN CONTROL MODULE (PCM) - ELECTRICAL DIAGNOSTICS - 545RE for diagnostic procedures.

OPERATION

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. From the state display screen, access either State Display Inputs and Outputs or State Display Sensors.

DESCRIPTION

The air injection pump is located on the left side of the engine compartment. The pump is operated by an internal electrical motor and is mounted to a bracket by rubber isolators. An inlet and outlet air hoses are attached to the air pump. A heat shield is attached at the air pump mounting bracket to ensure that the air pump is not damaged by heat coming off the exhaust system.

The electric air pump only functions during cold starts. The PCM will not command the electric air pump to run if the engine coolant temperature is 10° Celsius (18° Fahrenheit) above ambient temperature or if the engine coolant temperature is above 37° Celsius (98.6° Fahrenheit). The air pump will not run more than 20 seconds during this cold start condition. The air inlet tube to the electric air pump is equipped with a mass air flow (MAF) sensor. This MAF sensor monitors air flow to the exhaust system and is used to diagnose the system by making sure the correct amount of air, not too much or too little, reaches the exhaust system. Each component of the secondary air system is diagnosed assuming the other part is functioning correctly. The diagnostic tool can command the air pump ON with the key ON and engine OFF (KOEO).

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1. Disconnect and isolate negative battery.
2. Remove engine cover.
3. Remove air inlet tube (3) by pushing the ends (1) together while pulling the air inlet tube (3) away from air pump housing connection (2).
4. Remove air outlet tube by pushing the coupling ends together while pulling the air outlet tube away from the air pump.
5. Remove bolt (1) from heat shield (2) and air pump bracket (3).
6. Remove heat shield bolt (1) and heat shield (3) from air pump bracket (2).
7. Disconnect electrical harness connector (1) from the air pump electrical connector (2).
8. Remove air pump and bracket assembly from vehicle.
9. Remove air pump mounting nuts (5) from bracket (4).
10. Remove air pump (3) from bracket (4).

The air pump inlet tube is located on the left side of the engine compartment. The tube attaches to the air injection pump using a quick connect style fitting. The other end of the tube connects to the mass air flow sensor using a constant tension clamp.

Scheme 11

1. Cut the tie straps (3) being careful not to damage the air inlet tube (4).
2. Remove the constant tension clamp (2) and remove the mass air flow (MAF) sensor (1) from the air inlet tube (4). Position MAF sensor (1) and wiring aside.
3. Remove air inlet tube (3) by pushing the ends (1) together, while pulling the air inlet tube (3) away from air pump housing connection (2).

The air injection check valve (1) allows air pumped from the air injection pump to enter the exhaust manifold during cold engine starts only. Air pressure from the air injection pump causes the spring inside the air injection check valve to open allowing air to flow into the exhaust system.

All gasoline fueled vehicles use a maintenance free, evaporative (EVAP) canister. Fuel tank vapors vent into the canister. The canister temporarily holds the fuel vapors until intake manifold vacuum draws them into the combustion chamber. The Powertrain Control Module (PCM) purges the canister through the proportional purge solenoid. The PCM purges the canister at predetermined intervals and engine conditions. The proportional purge solenoid controls the purge rate of fuel vapors from the vapor canister and fuel tank to the engine intake manifold.

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1. Disconnect and isolate negative battery cable.
2. Remove the spare tire.
3. Raise and support vehicle.
4. Remove the 4 nuts (1) and the spare tire well (2).
5. Remove 2 nuts from EVAP canister mounting brackets and reposition EVAP canister assembly.
6. Disconnect purge line (4) from EVAP canister (1). Refer to «Fuel System/Fuel Delivery/FITTING, Quick Connect - Standard Procedure»(ref-353596-S35663758952010011200000) .
7. Remove fresh air hose (2) and electrical connector (3) from the ESIM.
8. Remove EVAP canister assembly from vehicle.
9. A lock tab (see arrow) is used on the back of the switch. Push lock tab towards switch while rotating switch counterclockwise 1/4 turn for removal.
10. Remove ESIM (1) from the EVAP canister (3).
11. Remove mounting brackets from EVAP canister.

Scheme 16

The picture displays a typical EVAP Canister and a typical ESIM switch. After installing any ESIM switch, the electrical connector on the switch must be in the 3 O'clock position. This step must be done for proper ESIM switch operation.

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1. The fresh air hose that attaches to the ESIM must have a clear opening to the atmosphere. Check the fresh air hose, including the fresh air filter, for obstructions or restrictions at the ESIM. If a restriction is present, the system will not allow free flow passage of clean air, and an early shut off of the fuel fill nozzle may occur during fuel fill.
2. Be sure O-ring (2) and EVAP canister opening are clean.
3. Install ESIM (1) to the EVAP canister (3).
4. Instal mounting brackets to EVAP canister assembly.
5. Install EVAP canister assembly to vehicle.
6. Install purge line (4) to EVAP canister (1). Refer to «Fuel System/Fuel Delivery/FITTING, Quick Connect - Standard Procedure»(ref-353596-S35663758952010011200000) .
7. Install fresh air hose (2) and electrical connector (3) to the ESIM. 1 - Nuts 2 - Spare Tire Well
8. Install the spare tire well (2) with 4 nuts (1).
9. Lower vehicle.
10. Install the spare tire.
11. Connect negative battery cable, tighten nut to 5 N.m (45 in. lbs.).

The plastic fuel fill cap is a threaded/quarter turn onto the end of the fuel filler tube. Its purpose is to retain vapors and fuel in the fuel tank.

The loss of any fuel vapor out of fuel filler tube is prevented by the use of 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.

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 proportional purge solenoid operates at a frequency of 200 hz and is controlled by an engine controller circuit that senses the current being applied to the proportional purge solenoid and then adjusts that current to achieve the desired purge flow. The proportional purge solenoid controls the purge rate of fuel vapors from the vapor canister and fuel tank to the engine intake manifold.

Scheme 18

1. Disconnect and isolate negative battery cable at battery.
2. If equipped with 2.7L or 3.5L engine, remove the PCM. Refer to «Electrical - Electronic Control Modules/Electronic Control Modules/MODULE, Powertrain Control - Removal»(ref-353582-S04164208822010011200000) .
3. Disconnect electrical connector (2) from evaporator purge solenoid (1).
4. Remove purge hose and quick connect fuel tank hose (3) from evaporator purge solenoid (1). Refer to «Fuel System/Fuel Delivery/FITTING, Quick Connect - Standard Procedure»(ref-353596-S35663758952010011200000) .
5. Release tab to remove evaporator purge solenoid (1) from bracket.

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

Scheme 19

When the engine is not operating or during an engine backfire, the spring forces the plunger back against the seat. This prevents vapors from flowing through the valve.

Scheme 20

When the engine is at idle or cruising, high manifold vacuum is present. At these times manifold vacuum is able to completely compress the spring and pull the plunger to the top of the valve. In this position there is minimal vapor flow through the valve.

Scheme 21

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

The EGR valve consists of three major components. First there is the pintle, valve seat, and housing which contains and regulates the gas flow. Second there is the armature, return spring, and solenoid coil to provide the operating force to regulate the flow by changing the pintle position. The solenoid coil assembly is in parallel with a diode and connects to the two connectors in the connector assembly. The third major component which senses pintle position and is connected to the three connectors in the electrical connector.

The exhaust gas recirculation flow is determined by the engine controller. For a given set of conditions, the engine controller knows the ideal exhaust gas recirculation flow to optimize NOx and fuel economy as a function of the pintle position. Pintle position is obtained from the position sensor. The engine controller adjusts the duty cycle of 128 Hz power supplied to the solenoid coil to obtain the correct position.

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Note. It is very important to disconnect the battery due to the addresses (cells) within the engine controller that store learned values related to powertrain operation. A malfunctioning EGR system can cause bad values to be stored in these cells that can cause an erroneous fault to occur after the system is repaired. Disconnecting the battery for at least two minutes will remove all power from the controller and reset these cells to normal default values.

Scheme 23

1. EGR system components and location. Upper tube (2), EGR valve (1), and Lower tube (3).
2. Disconnect negative battery cable.
3. Unlock and disconnect the electrical connector from EGR valve.
4. Remove the bolts from the EGR tube to exhaust manifold.
5. Remove the lower tube bolts to EGR valve and remove tube (3).
6. Remove upper tube bolts to EGR valve (2).
7. Remove the EGR valve mounting bolts (1).
8. Remove valve from vehicle.
9. Clean mounting surface.

Scheme 24

Note. It is very important to disconnect the battery due to the addresses (cells) within the engine controller that store learned values related to powertrain operation. A malfunctioning EGR system can cause bad values to be stored in these cells that can cause an erroneous fault to occur after the system is repaired. Disconnecting the battery for at least two minutes will remove all power from the controller and reset these cells to normal default values.

1. Disconnect and isolate negative battery cable at battery.
2. Remove EGR tube bolts (3) at exhaust gas recirculate (EGR) valve (2).
3. Remove EGR tube (4) from EGR valve (2).
4. Remove and discard gasket (5) located between EGR valve (2) and EGR tube (4).
5. Disconnect electrical connector at EGR valve (2).
6. Remove EGR valve mounting bolts (6).
7. Remove EGR valve (2) from cylinder head (1).
8. Remove and discard gasket located between EGR valve (2) and cylinder head (1).

Scheme 25

1. Clean mounting surface.
2. Install EGR valve.
3. Install the EGR valve mounting bolts (1).
4. Install new gasket between the EGR valve and upper tube and install bolts (2).
5. Install the lower tube to exhaust manifold.
6. Install new gasket between the EGR valve and lower tube and install bolts (3).
7. Tighten the lower tube to EGR valve bolts (3) to 12 N.m (106 in. lbs.).
8. Tighten the lower tube to exhaust manifold nuts to 70 N.m (51.5 ft. lbs.).
9. Tighten the upper tube to EGR valve bolts (2) to 12 N.m (106 in. lbs.).
10. Tighten EGR valve to cylinder head bolts (1) to 31 N.m (275 in. lbs.).
11. Tighten the upper tube to intake manifold bolts to 5 N.m (45 in. lbs.).
12. Connect the electrical connector to EGR valve and lock.
13. Connect negative battery cable and tighten nut to 5 N.m (45 in. lbs.).

Scheme 26

1. Install new exhaust gas recirculate (EGR) valve gasket to EGR valve.
2. Install EGR valve (2), gasket and bolts (6) to cylinder head (1). Tighten to 31 N.m (23 ft. lbs.).
3. Install new gasket (5), EGR tube (4) and bolts (3) to EGR valve (2). Tighten to 12 N.m (106 in. lbs.).
4. Tighten the EGR tube to intake manifold bolts to 5 N.m (45 in. lbs.).
5. Connect electrical connector to EGR valve (2).
6. Connect negative battery cable, tighten nut to 5 N.m (45 in. lbs.).

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.

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".

The Task Manager determines when tests happen and when functions occur. 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

The EGR system reduces oxides of nitrogen (NOx) in the engine exhaust. This is accomplished by allowing a predetermined amount of hot exhaust gas to recirculate and dilute the incoming fuel/air mixture.

A malfunctioning EGR system can cause engine stumble, sags, or hesitation, rough idle, engine stalling and poor driveability.

The system consists of

1. An EGR valve assembly, located toward the rear of the engine.
2. An EGR solenoid, located in the left rear of engine compartment near EGR valve. The EGR solenoid controls the "on time" of the EGR valve.
3. The ECM operates the EGR solenoid. The ECM is located under the hood next to the air cleaner housing.
4. The tandem pump supplies vacuum for the EGR solenoid and the EGR valve. This pump also supplies vacuum for operation of the power brake booster and the heating and air conditioning system. The pump is located in the rear of the cylinder head and is driven by the exhaust camshaft.
5. Vacuum lines and hoses connect the various components.

When the ECM supplies a variable ground signal to the EGR solenoid, EGR system operation begins. The ECM will monitor and determine when to supply and remove this variable ground signal. This will depend on inputs from the engine coolant temperature, throttle position and engine speed sensors.

When the variable ground signal is supplied to the EGR solenoid, vacuum from the tandem pump will be allowed to pass through the EGR solenoid and on to the EGR valve with a connecting hose.

Exhaust gas recirculation will begin in this order when

1. The ECM determines that EGR system operation is necessary.
2. The engine is running to operate the vacuum pump.
3. A variable ground signal is supplied to the EGR solenoid.
4. Variable vacuum passes through the EGR solenoid to the EGR valve.
5. The inlet seat (poppet valve) at the bottom of the EGR valve opens to dilute and recirculate exhaust gas back into the mixing chamber.

The EGR system will be shut down by the ECM after 60 seconds of continuous engine idling to improve idle quality.

Scheme 27

The EGR solenoid (4) is mounted to a bracket attached to the battery tray in the engine compartment. The EGR solenoid serves two different functions. One is to control vacuum bleed-off of the EGR valve. The other is to control the "on time" of the EGR valve.

The EGR valve is mounted to the intake manifold.

The engines use Exhaust Gas Recirculation (EGR) systems. The EGR system reduces oxides of nitrogen (NOx) in engine exhaust and helps prevent detonation (engine knock). Under normal operating conditions, engine cylinder temperature can reach more than 1649°C (3000°F). Formation of NOx increases proportionally with combustion temperature. To reduce the emission of these oxides, the cylinder temperature must be lowered. The system allows a predetermined amount of hot exhaust gas to recirculate and dilute the incoming air/fuel mixture. The diluted air/fuel mixture reduces peak flame temperature during combustion.

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1. Remove air inlet duct (3).
2. Disconnect negative battery cable.
3. Remove engine cover. Refer to «Engine - Removal»(ref-353574-S23427753412010011200000) .
4. Disconnect EGR valve vacuum line.
5. Disconnect EGR pipe (3) at EGR valve.
6. Remove air inlet tube from intake manifold flap motor (5).
7. Remove intake manifold flap motor (5).
8. Remove EGR valve retaining bolts and remove EGR valve (7).

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1. Inspect EGR and intake manifold flap motor o-rings (6,8) for damage. Replace as necessary.
2. Install EGR valve (7) to intake manifold. Torque retaining bolts to 10.m (88 lbs.in.).
3. Install intake manifold flap motor (5) to EGR valve (7). Torque retaining bolts to 10 N.m (88 lbs.in.).
4. Inspect EGR pipe gasket (4)for damage, replace as necessary.
5. Connect EGR pipe (3) to EGR valve. Torque retaining bolts to 20N.m (177 lbs.in.).
6. Connect EGR valve vacuum line.
7. Install engine cover. Refer to «Engine - Installation»(ref-353574-S32878774952010011200000) .
8. Connect negative battery cable.
9. Install air inlet duct (3).