Emissions Control System: Overview Chrysler Crossfire I

Scheme 11

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 as well as continuity tests (opens/shorts). Previously, a component like the Throttle Position Sensor (TPS) was checked by the Powertrain Control Module (PCM) for an open or shorted circuit. If one of these conditions occurred, a Diagnostic Trouble Code (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 Manifold Absolute Pressure (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 appropriate Engine ELECTRICAL DIAGNOSTICS article for diagnostic procedures.

The following is a list of the monitored components

1. Catalyst Monitor
2. Comprehensive Components
3. Exhaust Gas Recirculation (EGR)
4. Fuel Control (rich/lean)
5. Oxygen Sensor Monitor
6. Oxygen Sensor Heater Monitor
7. Purge
8. Misfire
9. Evaporative Vacuum Leak Detection (EVLD)

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 system 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 Lamp (MIL) will be illuminated. These monitors generate Diagnostic Trouble Codes that can be displayed with the a DRB III(R) scan tool.

The following is a list of the system monitors

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

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

Refer to the appropriate Engine ELECTRICAL DIAGNOSTICS article for diagnostic procedures.

DESCRIPTION - NON-MONITORED CIRCUITS

The PCM does not monitor all circuits, systems and conditions that could have malfunctions causing driveability problems. However, malfunctions in these systems may cause the PCM to store diagnostic trouble codes for other systems or components. For 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.

The major non-monitored circuits are listed below along with examples of failure modes that do not directly cause the PCM to set a DTC, but instead for a system that is monitored.

DESCRIPTION - DRB III(R) STATE DISPLAY TEST MODE

The switch (component) inputs to the Powertrain Control Module (PCM) have two recognized states; HIGH and LOW. 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 - 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.

DESCRIPTION - TRIP DEFINITION

A "Trip" means vehicle operation (following an engine-off period) of duration and driving mode such that all components and systems are monitored at least once by the diagnostic system. The monitors must successfully pass before the PCM can verify that a previously malfunctioning component is meeting the normal operating conditions of that component. For misfire or fuel system malfunction, the MIL may be extinguished if the fault does not recur when monitored during three subsequent sequential driving cycles in which conditions are similar to those under which the malfunction was first determined.

Anytime the MIL is illuminated, a DTC is stored. The DTC can self erase only after the MIL has been extinguished. Once the MIL is extinguished, the PCM must pass the diagnostic test for the most recent DTC for 40 warm-up cycles (80 warm-up cycles for the Fuel System Monitor and the Misfire Monitor). A warm-up cycle can best be described by the following

1. The engine must be running
2. A rise of 4.4°C (40°F) in engine temperature must occur from the time engine was started
3. Engine coolant temperature must crossover 71°C (160°F)
4. A "driving cycle" that consists of engine start up and engine shut off.

Once the above conditions occur, the PCM is considered to have passed a warm-up cycle. Due to the conditions required to extinguish the MIL and erase the DTC, it is most important that after a repair has been made, all DTCs be erased and the repair verified by running 1 good trip.

DESCRIPTION - VEHICLE EMISSION CONTROL INFORMATION LABEL

All models have a Vehicle Emission Control Information (VECI) Label. DaimlerChrysler permanently attaches the label in the engine compartment. It cannot be removed without defacing information and destroying the label.

The label contains the vehicle's emission specifications and vacuum hose routings. All hoses must be connected and routed according to the label.

OPERATION - SYSTEM

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 often 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 warmup cycles. Diagnostic trouble codes that affect vehicle emissions 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 the 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.

There are several operating conditions for which the PCM monitors and sets DTCs. Refer to DESCRIPTION - MONITORED COMPONENTS , DESCRIPTION - MONITORED SYSTEMS and DESCRIPTION - NON-MONITORED CIRCUITS .

Note. 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 the misfire code. When a repair is completed and verified, use the DRB III(R) scan tool to erase all DTCs and extinguish the MIL.

Scheme 12

Technicians can retrieve stored DTCs. For obtaining the DTC information, use the Data Link Connector (2) with the DRB III(R) scan tool.

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 often 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 warmup cycles. Diagnostic trouble codes that affect vehicle emissions 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 the 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.

There are several operating conditions for which the PCM monitors and sets DTCs. Refer to DESCRIPTION - MONITORED COMPONENTS , DESCRIPTION - MONITORED SYSTEMS and DESCRIPTION - NON-MONITORED CIRCUITS .

Note. 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 the misfire code. When a repair is completed and verified, use the DRB III(R) scan tool to erase all DTCs and extinguish the MIL.

Scheme 13

Technicians can retrieve stored DTCs. For obtaining the DTC information, use the Data Link Connector (2) with the DRB III(R) scan tool.

DESCRIPTION - EVAPORATION CONTROL SYSTEM

The Evaporation Control System prevents the emission of fuel tank vapors into the atmosphere. When fuel evaporates in the fuel tank, the vapors pass through vent hoses or tubes to an activated carbon filled evaporative canister. The canister temporarily holds the vapors. The Powertrain Control Module (PCM) allows intake manifold vacuum to draw vapors into the combustion chambers during certain operating conditions.

This vehicle uses a pulse-width modulated EVAP Purge Solenoid System. The PCM controls vapor flow by operating the EVAP Purge Solenoid. Refer to EVAP PURGE SOLENOID .

Note. The evaporative system uses specially manufactured hoses. If they need replacement, only use fuel resistant hose. Also the hoses must be able to pass an Ozone compliance test.

Note. For more information on Onboard Refueling Vapor Recovery (ORVR), refer to FUEL DELIVERY .

DESCRIPTION

The Charcoal Canister Shutoff Valve is part of the Evaporative Vacuum Leak Detection (EVLD) system. The Charcoal Canister Shutoff Valve is mounted on the EVAP Canister. This assembly is located above a splash shield in front of the right rear axle shaft.

OPERATION

The Charcoal Canister Shutoff Valve is actuated by the PCM to isolate the EVAP Purge System in order to determine if a leak exists in any of the purge system components.

This vehicle uses a pulse-width modulated EVAP Purge Solenoid. The solenoid regulates the rate of vapor flow from the EVAP canister to the throttle body. The PCM controls the frequency at which the solenoid operates in order to customize the vapor volume for each cylinder.

The PCM will only energize the EVAP solenoid when the engine is at operating temperature, but will de-energize it during periods of deceleration. When de-energized, no vapors are purged.

The pulse-width modulated EVAP Purge Solenoid controls the fuel vapor purge rate from the Vapor Canister and fuel tank to the engine intake manifold.

Scheme 14

1. Disconnect harness connector from solenoid (2).
2. Disconnect vapor hoses (1 and 4) from solenoid (3).
3. Remove solenoid (3) from bracket (5).

Scheme 15

1. Disconnect harness connector from solenoid (2).
2. Disconnect vapor hoses (1 and 4) from solenoid (3).
3. Remove solenoid (3) from bracket (5).

The plastic/metal Fuel Filler Cap is installed with a 1/4 turn onto the end of the fuel filler tube. Its purpose is to retain vapors and fuel in the fuel tank.

The Fuel Filler Cap incorporates a two-way relief valve that is closed to atmosphere during normal operating conditions. The relief valve is calibrated to open when a pressure of 172 mbar (2.5 psi) or vacuum of 20 mbar (8 in H2O) occurs in the fuel tank. When the pressure or vacuum is relieved, the valve returns to the normally closed position.

The Onboard Refueling Vapor Recovery (ORVR) System is used to remove excess vapors in the fuel tank during refueling.

Scheme 16

The Onboard Refueling Vapor Recovery (ORVR) System is an emission control device. The principle used in the ORVR system is that the fuel flowing into the fuel filler tube (3) creates an aspiration effect which draws air into the fuel filler tube (3). During refueling, the fuel tank (2) is vented to the EVAP Canister (7) to capture escaping vapors. With air flowing into the fuel filler tube (3), there are no fuel vapors escaping to the atmosphere. Once the refueling vapors are captured by the EVAP Canister (7), 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 EVAP Purge Solenoid (6) so that there is minimal or no impact on driveability or tailpipe emissions.

As fuel starts to flow through the Fuel Filler Tube (3), it opens the normally closed Fuel Filler Tube Check Valve (4) and enters the Fuel Tank (2). Vapor or air is expelled from the tank through the tank vent/rollover valves (1) to the EVAP Canister (7). Vapor is absorbed in the canister (7) until vapor flow in the lines stops, either following refueling shut-off or by having the fuel level in the tank rise high enough to close the check valves in the tank vent/rollover valves (1). The fuel filler tube (3) also incorporates a fuel tank overfill check valve (5). As fuel level rises, the fuel tank overfill check valve (5) seals the in-tank end of the fuel filler tube (3). This largely prevents overfilling of the Fuel Tank (2). At this point in the fueling of the vehicle, the tank pressure increases, the fuel filler tube check valve (4) closes (preventing tank fuel from spitting back at the operator), and fuel then rises up the filler tube (3) to shut-off the dispensing nozzle.

The EVAP Canister is located above a splash shield in front of the right rear axle shaft.

This vehicle uses a maintenance-free, Evaporative (EVAP) Canister filled with activated carbon granules. Fuel tank vapors are vented into the canister where they are absorbed by the activated carbon granules. 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 pulse-width modulated EVAP Purge Solenoid. The PCM purges the canister at predetermined intervals and engine conditions.

Scheme 17

Scheme 18

1. Disconnect the negative battery cable.
2. Raise and support the vehicle.
3. Remove the shield retaining nuts from splash shield.
4. Remove the splash shield.
5. Carefully disconnect the vapor/vacuum/vent hoses (2).
6. Slide the EVAP canister (4) to the left, off of mounting bracket.
7. Disconnect the charcoal canister shutoff valve harness connector (1).
8. Depress the locking tab (2) to release charcoal canister shutoff valve (1).
9. While holding the lock tab (2) in release position, turn charcoal canister shutoff valve (1) clockwise and remove from EVAP canister.
10. Discard the old O-ring (3).

The Exhaust Gas Recirculation flow is determined by the Powertrain Control Module (PCM). For a given set of conditions, the PCM calculates the ideal exhaust gas recirculation flow to minimize NOx emissions and maximize fuel economy by adjusting the pintle position. Pintle position is controlled by the EGR Solenoid. The PCM adjusts the duty cycle of the power supplied to the solenoid coil to obtain the correct position.

Scheme 19

Scheme 20

1. Disconnect the negative battery cable.
2. Remove the air cleaner housing.
3. Disconnect the solenoid harness connector (1).
4. Disconnect the solenoid to valve vacuum line (2).
5. Remove the EGR tube flange nut (2) at valve.
6. Remove the solenoid to valve mounting bolt (3).
7. Remove the valve to cylinder head mounting bolts (1).
8. Clean the gasket surfaces. Discard the old gasket.
9. Clean the EGR passages as necessary.

Scheme 21

1. Position new gasket between the valve and cylinder head.
2. Loosely install valve front bolt (1) to cylinder head, do not tighten bolt.
3. Position solenoid to valve and loosely install solenoid (3) to valve bolt.
4. Loosely install valve rear bolt (2) to cylinder head, do not tighten bolt.
5. Loosely install the EGR tube flange nut (2) to valve.
6. Tighten the valve to cylinder head bolts (1) to 31 N.m (23 ft. lbs.).
7. Tighten the flange nut (2) to 11 N.m (95 in. lbs.).
8. Tighten the solenoid to valve bolt (3) to 11 N.m (95 in. lbs.).
9. Connect the solenoid harness connector (1).
10. Connect the vacuum hose (2).
11. Install the air cleaner housing.
12. Connect the negative battery cable.

Scheme 22

This vehicle is equipped with an Air Pump that injects air into the exhaust to reduce the emissions during engine warm-up. The air injected into the exhaust will cause the catalytic converters to heat up more quickly. This will improve the emission levels during a cold start. The Air Pump Switchover System incorporates an Air Pump (4) with two Air Pump Switchover Valves (1 and 6), an Air Pump Switchover Solenoid (3), an Air Pump Relay, a Vacuum Check Valve (5) and the PCM.

The Air Pump Relay is located in the Relay Control Module and can be easily identified by referring to the relay control module label. The Air Pump is mounted to the top center of the engine timing cover. The Air Pump Switchover valves (1 and 6) are located at the front, top of the engine, mounted just in front of the left and right cylinder covers. The Air Pump Switchover Solenoid (3) is mounted on the right front of the engine, just below the Air Pump Switchover Valve RH (6).

Scheme 23

Air is allowed to enter the exhaust when the PCM simultaneously actuates the Air Pump Relay, Air Pump (1), and Air Pump Switchover Solenoid (4) after engine start-up for up to 2 1/2 minutes. The following conditions must also be met in order for the system to become active

1. Coolant Temperature >10°C (50°F) but <60°C (140°F)
2. Engine Speed <3000 RPM
3. Throttle Valve Not Wide Open

After an actuation, the air injection system will remain deactivated until the coolant temperature drops from >60°C (140°F) to <40°C (104°F).

The Air Pump (1) draws in air through a maintenance-free filter and pumps it to the Air Pump Switchover Valves (3 and 6). The Air Pump Switchover Valves (3 and 6) prevent exhaust gases from flowing back into the Air Pump (1).

The Air Pump Switchover Solenoid (4) is supplied with vacuum from the intake manifold through a check valve (5). When the Air Pump Switchover Solenoid (4) is activated, it passes engine vacuum to the Air Pump Switchover Valves (3 and 6). The air which is delivered via the Air Pump Switchover Tube (2) is forced through the valves into the cylinder head openings to the exhaust. The injected air reacts with the hot exhaust gases in the outlet port. An oxidation of carbon monoxides (CO) and hydrocarbons (HC) takes place and results in an additional increase in the exhaust temperature.

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 called the Task Manager.

OPERATION - TASK MANAGER

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