P1CEA-00-BOOST SIDE EVAP PURGE SYSTEM PERFORMANCE
For a complete wiring diagram, refer to the Wiring Information.
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Theory of Operation
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EVAPORATIVE SYSTEM OVERVIEW: The Powertrain Control Module (PCM) monitors the Evaporative Emission System operation. The primary concern being monitored is the integrity of the system against leaks. The basic strategy used is that in a sealed system, pressure will naturally increase or decrease in relation to temperature. As temperature increases, so does pressure inside the system. And conversely, as temperature decreases, pressure in the system will decrease as well and will eventually turn into a vacuum if no leaks are present. Even the smallest of leaks can be accurately detected in this manner. The ESIM has multiple functions. There are two weighted seals that keep the system normally closed from the atmosphere. The weighted seals are used to maintain the system pressure between +1 inch of water and -2 inches of water. Anytime (engine-on or engine-off) that pressure or vacuum reaches these thresholds, the weights will lift and provide relief. There is also an internal vacuum actuated switch that closes when the vacuum reaches a calibrated value. 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 higher built up pressure.
ESIM SWITCH STUCK CLOSED MONITOR: At ignition off, the state of the ESIM switch is evaluated. If the switch is open, a pass flag is set and PCM will complete power down. If the switch is closed, the PCM will wait a calibrated delay time and open the OBD Vent Valve. This should vent the vacuum in the Fuel Tank to atmosphere through the Intake Manifold. If the switch opens, a pass flag is set and the PCM will power down. If the PCM detects that the ESIM switch is still closed after a calibrated time, an error is detected and a switch stuck closed failure is set at the next engine run cycle.
SMALL LEAK MONITOR: This is an accumulative monitor and the data from each valid event is recorded and added to the previously recorded events. The PCM timer records the engine on/drive cycle and engine off time for each small leak monitor event. For an event to be valid the PCM must see;
1.An engine on/drive cycle for a minimum of 10 minutes.
NOTE: The engine on timer will stop counting after a maximum of 26 minutes.
2.And, when the engine is shut down, an engine off timer starts. There is a 12 minute delay time in which the PCM will ignore ESIM Switch input. The engine off timer period will continue to count until one of the three conditions exist:
•The engine is started without a switch closure during the event.
NOTE: At the next key on cycle a determination is made as to whether the event was valid and the information is kept.
•An ESIM Switch closed input is received after the 12 minute delay during the event.
NOTE: If the switch closed input is received, the PCM records that the switch has closed, stores the engine shut down time, then goes to sleep.
•After a maximum of 1051 minutes without an ESIM Switch closure during the event.
The accumulative monitor will increment and start over after both timers have reached a calibrated threshold (Engine on - 100 minutes and Engine off - 4200 minutes). When the monitor has exceeded the calibrated accumulated engine on and engine off thresholds, the system is evaluated and the accumulated timer starts over.
LEAK SIZE DETERMINATION: If the PCM did not see an ESIM Switch closed signal during the previous ignition off cycle, and the event was valid, an intrusive leak test is run to determine if a large leak is present on the next cold start.
Immediately after start-up, while the engine is cold, the Purge Solenoid is opened to create a vacuum in the evaporative system to a calibrated vacuum point that is beyond the ESIM Switch closing threshold. The pass/fail time will vary based on the total fuel volume at the time of the test.
•If the switch does not close at all during purging, because of a switch that is stuck open or vacuum cannot be created below 1.0 in Hg within a calibrated time threshold, it is determined to be a general evaporative system failure (P0440).
•If vacuum is created and the switch has closed, the PCM monitors how long it takes for the switch to open. If the switch opens before the maximum calibrated time, it is determined to be a large leak (P0455).
•If vacuum is created and the switch has closed, the PCM monitors how long it takes for the switch to open. If the switch stays closed longer than a maximum calibrated time before opening, it is determined that a large leak is not present and the Small Leak Monitor will continue to run until the accumulative monitor increments. If no ESIM Switch closures were recorded during the entire increment, it is determined that a small leak is present (P0456)
PURGE FLOW MONITOR: The operation of the Purge Solenoid and evaporative purge flow is monitored using inputs from the ESIM Switch and Fuel Tank Pressure Sensor. The Purge Flow Monitor will only run if the Small Leak Monitor recorded a pass on the previous ignition off event and the test data was valid. Because the leak detection diagnostics can only verify that the fuel tank system is sealed while the purge valve is closed, it cannot determine if the purge line between the solenoid and Intake Manifold is pinched or leaking. The Purge Flow Monitor is needed to verify these failure modes. The Purge Flow Monitor works on the premise that as flow through the system increases, so does the pressure drop in the system. The PCM monitors the Fuel Tank Pressure Sensor and looks for increasing vacuum in the Fuel Tank with increasing purge flow. Conversely, it looks for decreasing vacuum in the Fuel Tank with decreasing flow.
•With the engine running and enable conditions met, the non-intrusive purge monitor looks for a calibrated increase in vacuum in the fuel tank with increased purge flow, referred to as phase 1. If phase 1 passes, the purge monitor looks for a calibrated decrease in vacuum in the Fuel Tank with decreasing purge flow, referred to as phase 2. If phase 2 passes, the purge monitor is complete. If the purge flow monitor fails either phase, or does not complete both phases within a specified time, an intrusive test is initiated to verify the results from the non-intrusive test.
•The intrusive diagnostic uses the same two phases to analyze the system. However, the intrusive test actuates the Purge Solenoid such that the differences are much more pronounced allowing a more accurate test result. If the PCM detects a failure during the intrusive test, a purge system performance fault is set (P0441).
PURGE FLOW MONITOR IN BOOST: Turbocharged engines purge while the engine is in boost. This is achieved by having additional purge hoses and Hardware. The Boost purge monitor is used to check that this part of the Evaporative emissions system is correctly operating. The Purge flow monitor in boost is enabled to run this trip the exact same way as Purge Flow Monitor.
•The Turbo Purge Monitor will only go intrusive on this trip after a small leak passing event.
•The Monitor will only run when there is a sustained stable boost condition and not when the vehicle is at wide open throttle.
•The Monitor waits a calibrated time while stabilized boost is achieved, it then turns on the OBD Bypass Valve (#19) to relieve vacuum only. It then turns on the purge and the monitor looks for only a phase 1 decrease in vacuum in the fuel tank. If the vacuum cannot be achieved the monitor fails. (P1CEA)
When Monitored and Set Conditions
When Monitored: This diagnostic runs when the following conditions are met:
•With the ignition engine running during a boost condition.
•Fuel level above 12 percent.
•Ambient temperature between 4.0°C and 35°C (39.2°F and 95°F).
•Vehicle speed between 8 km/h and 128.7 km/h (5 mph and 80 mph).
Set Conditions:
•The Powertrain Control Module (PCM) detects insufficient vapor flow detected in the evaporative system operation during a boost condition.
Default Actions:
•The MIL light will illuminate.
Possible Causes
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Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
1.VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION
1. Turn the ignition on.
2. With the scan tool, read DTCs. Record the Freeze Frame data if any DTCs are present.
3. Whether or not any DTCs are Active you will want to check the following items which may assist in repairing the customer's complaint successfully.
•Check the vehicle's repair history.
•If the vehicle has a repair history that pertains to the customer's current complaint, review the repair.
•Inspect the vehicle for any aftermarket accessories that may have been installed incorrectly.
•Check for any service bulletin(s) related to the customer's complaint or DTCs.
•If a service bulletin applies, follow the instructions per the service bulletin.
Choose the following scenario that applies.
The service bulletin repaired the customer's complaint.
•Testing complete.
A DTC is present, no service bulletins apply or the service bulletin didn't repair the customer's complaint.
•Go To 2
2.CHECK FOR AN ACTIVE DTC
NOTE: If there are any Fuel Tank Pressure Sensor DTCs present, diagnose and repair those DTCs before continuing with this test procedure.
1. Start the engine.
2. Test drive the vehicle in accordance with the set conditions.
3. With the scan tool, read DTCs.
NOTE: If any other DTC sets, active or pending, perform the diagnostic procedure for that DTC before proceeding with this test.
Is the DTC active or pending?
Yes
•Go To 3
No
•Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
3.CHECK THE (N8) FTP SENSOR SUPPLY CIRCUIT FOR VOLTAGE
1. Turn the ignition off.
2. Disconnect the FTP Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage between ground and the (N8) FTP Sensor Supply circuit at the FTP Sensor harness connector.
Is the voltage between 4.8 and 5.2 volts?
Yes
•Go To 4
No
•Repair the (N8) FTP Sensor Supply circuit for an open circuit or short to ground.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
4. CHECK FOR HIGH RESISTANCE IN THE (N7) FTP SENSOR SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance of the (N7) FTP Sensor Signal circuit between the FTP Sensor harness connector and the PCM C1 harness connector.
Is the resistance below 3.0 Ohms?
Yes
•Go To 5
No
•Repair the (N7) FTP Sensor Signal circuit for an open or high resistance.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
5.CHECK FOR HIGH RESISTANCE IN THE (N10) FTP SENSOR RETURN CIRCUIT
1. Measure the resistance of the (N10) FTP Sensor Return circuit between the FTP Sensor harness connector and the PCM C1 harness connector.
Is the resistance below 3.0 Ohms?
Yes
•Go To 6
No
•Repair the (N10) FTP Sensor Return circuit for an open or high resistance.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
6.VISUALLY INSPECT THE TURBO RELATED EVAPORATIVE SYSTEM COMPONENT
1. Turn the ignition off.
2. Perform a visual and physical inspection of the Turbo related Evaporative Emission system components. Check for the following conditions:
•Verify the flow direction arrow on the tee on the boost vacuum purge harness is pointing from the Charge Air Cooler (CAC) (high pressure) to the air induction (low pressure)
•Check for the Purge Solenoid vacuum hose to be pinched/bent/blocked between the intake manifold to purge solenoid
•Check for the Evap purge hose to be pinched/bent/blocked between Purge Solenoid, Fuel tank and Evap Purge Canister
•Check for blockage/obstruction between CAC port and the ejector tee
Were any of the above conditions found?
Yes
•Repair as necessary.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
•Go To 7
7.VISUALLY INSPECT THE REMAINDER OF THE SYSTEM
1. Turn the ignition off.
2. Perform a visual and physical inspection of the entire Evaporative Emission system. Check for the following conditions:
•Improper installation of the Fuel Fill Cap
•Holes or cracks
•Loose seal points
•Evidence of damaged components
•Incorrect routing of hoses and tubes
•Loose or missing Fuel Filler Cap
•Damaged Locking tabs on Fuel Cap and/or fill tube
•Damaged seal points on Fuel Cap and/or fill tube
•Fuel cap gasket seal
Were any of the above conditions found?
Yes
•Repair as necessary.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
•Go To 8
8.EVAP PURGE SOLENOID
NOTE: To continue testing you will need the Evaporative Emission Leak Detector (EELD) Kit, EELD And Accessory 8404C .
WARNING:
Keep lit cigarettes, sparks, flames, and other ignition sources away from the test area to prevent the ignition of explosive gases, Keep the test area well ventilated.
1. Connect the red power lead of the EELD to the battery positive terminal and the black ground lead to battery negative terminal.
2. Disconnect the vacuum hoses at the Evap Purge Solenoid.
3. Connect the SMOKE supply tip (black hose) to the “CAN” port on the Evap Purge Solenoid.
4. Set the smoke/air control switch to SMOKE.
5. While still holding the remote smoke/air start button, check to see if smoke is exiting the purge valve. This indicates that there is a leak internal to the purge valve.
NOTE: This is an optional method of checking the purge valve for leaks if the EELD is unavailable.
6. Using a hand vacuum pump, apply 10 in Hg to the "CAN" side of the Purge Solenoid.
7. Observe the vacuum gauge for at least 15 seconds.
NOTE: The solenoid should hold vacuum for a minimum of 15 seconds.
Is smoke visible from the Purge Solenoid or does it NOT hold a vacuum?
Yes
•Verify that there is good pin to terminal contact at the Purge Solenoid and the Powertrain Control Module connectors. Replace the Purge Solenoid if no problems were found in the connectors.
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
•Go To 9
9.CHECK RELATED PCM AND COMPONENT CONNECTIONS
1. Perform any Service Bulletins that apply.
2. Disconnect all PCM harness connectors.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
•Proper connector installation.
•Damaged connector locks.
•Corrosion.
•Other signs of water intrusion.
•Weather seal damage (if equipped).
•Bent terminals.
•Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
•Terminals that have been pushed back into the connector cavity.
•Check for spread terminals and verify proper terminal tension.
Repair any conditions that are found.
6. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
10. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
11. With the scan tool, read DTCs.
Did the DTC return?
Yes
•Replace the Powertrain Control Module in accordance with the Service information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control - Removal) .
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
•Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
•Test complete.
