Emissions Control System: Overview Dodge Avenger II

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.

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The Powertrain Control Module (PCM) monitors many different circuits in the fuel injection, ignition, emission and engine systems. If the PCM senses a problem with a monitored circuit and the fault occurs multiple times enough to indicate an actual problem, it stores a Diagnostic Trouble Code (DTC) in the PCM's memory. If the code applies to a non-emissions related component or system, and the problem is repaired or ceases to exist, the PCM cancels the code after 40 warm-up cycles. Diagnostic trouble codes that affect vehicle emissions will illuminate the Malfunction Indicator Lamp (MIL).

Certain criteria must be met before the PCM stores a DTC in memory. The criteria may be a specific range of engine RPM, engine temperature, and/or input voltage to the PCM.

The PCM might not store a DTC for a monitored circuit even though a malfunction has occurred. This may happen because one of the DTC criteria for the circuit has not been met. For example , assume the diagnostic trouble code criteria requires the PCM to monitor the circuit only when the engine operates between 750 and 2000 RPM. Suppose the sensor's output circuit shorts to ground when engine operates above 2400 RPM (resulting in 0 volt input to the PCM). Because the condition happens at an engine speed above the maximum threshold (2000 RPM), the PCM will not store a DTC.

For information on obtaining DTC information. Refer to STANDARD PROCEDURE .

Various diagnostic procedures may actually cause a diagnostic monitor to set a DTC. For instance, pulling a spark plug wire to perform a spark test may set a misfire code. When a repair is completed and verified, use the scan tool to erase all DTC's and extinguish the MIL.

There are several operating conditions for which the PCM monitors and sets DTC's. Refer to MONITORED SYSTEMS , NON-MONITORED CIRCUITS and MONITORED COMPONENT .

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 more than 10°Celsius (50°Fahrenheit) than ambient temperature, and when the coolant temperature is greater than 37°Celsius (98.6°Fahrenheit). The amount of time the pump will run is based on the amount of air flowing into the system. The amount of air flowing into the system is measured by a mass air flow sensor located at the air inlet tube. The maximum time the electric air pump will run is for 18 seconds.

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1. Disconnect and isolate negative battery cable at battery.
2. 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).
3. Remove bolt (1) from heat shield (2) and air pump bracket (3).
4. Remove heat shield bolt (1) and heat shield (3) from air pump bracket (2).
5. Disconnect electrical harness connector (1) from the air pump electrical connector (2).
6. Remove air pump mounting nuts (5) from bracket (4).
7. 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 8

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.

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.

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1. Disconnect the negative battery cable.
2. Raise and support vehicle.
3. Disconnect electrical connector (1).
4. Disconnect the hoses from the EVAP canister (2).
5. Remove filter hose from EVAP canister (2).
6. Remove mounting fasteners from bracket of the EVAP canister (1).
7. Remove EVAP canister assembly.

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

The ORVR (On-Board Refueling Vapor Recovery) system is used to store and prevent the release into the atmosphere of the 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.

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.

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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.

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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.

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).

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1. Clean mounting surface.
2. Install EGR valve.
3. Install the EGR valve mounting bolts (1).
4. Inspect rubber silicone seals on intake manifold end of EGR tube.
5. Install upper tube into the intake manifold, being careful that the silicone rubber seals are correctly installed and undamaged.
6. Install new gasket between the EGR valve and upper tube and install bolts (2).
7. Install the lower tube to exhaust manifold.
8. Install new gasket between the EGR valve and lower tube and install bolts (3).
9. Tighten the lower tube to EGR valve bolts (3) to 11 N.m (95 in. lbs.) torque.
10. Tighten the lower tube to exhaust manifold bolts to 31 N.m (275 in. lbs.) torque.
11. Tighten the upper tube to EGR valve bolts (2) to 11 N.m (95 in. lbs.) torque.
12. Tighten EGR valve to cylinder head bolts (1) to 31 N.m (275 in. lbs.) torque.
13. Connect the electrical connector to EGR valve and lock.
14. Connect negative battery cable.

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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 30 N.m (22 ft. lbs.).
3. Install new gasket (5), EGR tube (4) and bolts (3) to EGR valve (2). Tighten to 15 N.m (11 ft. lbs.).
4. Connect electrical connector (6) to EGR valve (1).
5. Connect negative battery cable, tighten nut to 5 N.m (45 in. lbs.).

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.

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 «REMOVAL»(ref-305761-S28982146422008120200000) . Refer to «REMOVAL»(ref-305762-S42490331882008120200000) . Refer to «REMOVAL»(ref-305763-S31788323032008120200000) .
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 N.m (88 in. lbs.).
3. Install intake manifold flap motor (5) to EGR valve (7). Torque retaining bolts to 10 N.m (88 in. lbs.).
4. Inspect EGR pipe gasket (4)for damage, replace as necessary.
5. Connect EGR pipe (3) to EGR valve. Torque retaining bolts to 20 N.m (177 in. lbs.).
6. Connect EGR valve vacuum line.
7. Install engine cover. Refer to «INSTALLATION»(ref-305761-S22122121902008120200000) . Refer to «INSTALLATION»(ref-305762-S26783515592008120200000) . Refer to «INSTALLATION»(ref-305763-S01022302712008120200000) .
8. Connect negative battery cable.
9. Install air inlet duct (3).

The EGR solenoid valve block is mounted in the left-rear of 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.

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1. Remove air inlet duct.
2. Disconnect negative battery cable.
3. Remove air cleaner housing. 1 - Item_1 2 - Item _2
4. Disconnect solenoid valve block harness connector (1).
5. Disconnect vacuum harness (2) from solenoid valve block.
6. Remove solenoid valve block from bracket.

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