Alero, Grand Am 1999-2005

Evaporative Emission Control System

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EVAP Canister Purge & Vent Solenoids



Removal & Installation
Purge Solenoid Valve
2.2L (L61) Engine
  1. Disconnect the evaporative emission (EVAP) canister purge valve harness connector.
  2.  
  3. Disconnect the vacuum pipe from the EVAP canister purge valve.
  4.  
  5. Disconnect the purge pipe from the EVAP canister purge valve.
  6.  
  7. Remove the EVAP canister purge valve and bracket.
  8.  
  9. Remove the EVAP canister purge valve from the purge bracket.
  10.  
  11. Inspect for carbon release in the EVAP canister purge valve ports.
  12.  

To install:

  1. Install the EVAP canister purge valve on to the purge bracket.
  2.  
  3. Install the EVAP canister purge valve and bracket. Tighten the purge bracket nut to 71 inch lbs. (8 Nm).
  4.  
  5. Connect the purge pipe to the EVAP canister purge valve.
  6.  
  7. Connect the vacuum pipe to the EVAP canister purge valve.
  8.  
  9. Connect the EVAP canister purge valve harness connector.
  10.  
  11. Remove the air cleaner outlet resonator.
  12.  
  13. Disconnect the EVAP canister purge valve harness connector.
  14.  
  15. Disconnect the engine purge pipe from the EVAP canister purge valve.
  16.  
  17. Disconnect the engine vacuum pipe from the EVAP canister purge valve.
  18.  
  19. Remove the EVAP canister purge valve mounting bracket attaching bolt.
  20.  
  21. Remove the EVAP canister purge valve along with the mounting bracket.
  22.  
  23. Installation is the reverse of the removal procedure. Tighten the bracket bolts to 71 inch lbs. (8 Nm).
  24.  

2.4L Engines
  1. Remove the front purge pipe from the evaporative emission (EVAP) canister purge valve.
  2.  
  3. Remove the rear purge pipe from the EVAP canister purge valve.
    NOTE
    The EVAP canister may have released carbon particles, which caused this part to fail, and may cause damage to other components. Check the EVAP canister for loose carbon before returning the vehicle to service.

  4.  
  5. Disconnect the EVAP canister purge valve electrical connector.
  6.  
  7. Insert a screwdriver between the EVAP canister purge valve and the mounting bracket in order to release the lock tab.
  8.  
  9. Remove the EVAP canister purge valve mounting bracket attaching nut, if replacing the bracket.
  10.  
  11. Remove the bracket.
  12.  

To install:

  1. Install the mounting bracket and the attaching nut for the EVAP canister purge valve. Tighten the nut to 71 inch lbs. (8 Nm).
  2.  
  3. Slide the EVAP canister purge valve onto the mounting bracket. Make sure the lock tab locks the valve in place.
  4.  
  5. Connect the EVAP canister purge valve electrical connector.
  6.  
  7. Connect the rear purge pipe to the EVAP canister purge valve.
  8.  
  9. Connect the front purge pipe to the EVAP canister purge valve.
  10.  

Vent Solenoid Valve
2.2L & 2.4L Engines
  1. Raise the vehicle
  2.  
  3. Loosen the EVAP canister vent valve hose clamp and slide the clamp down the hose away from the EVAP vent valve hose connection.
  4.  
  5. Remove the hose from the EVAP canister vent valve.
  6.  
  7. Remove the EVAP canister vent valve by placing a pry bar between the valve and mounting surface, and moving the valve forward.
  8.  
  9. Remove the clip from the EVAP canister vent valve harness connector
  10.  
  11. Disconnect the EVAP canister vent valve harness connector.
  12.  

To install:

  1. Connect the EVAP canister vent valve harness connector
  2.  
  3. Install the clip into the EVAP canister vent valve harness connector.
  4.  
  5. Install the EVAP canister vent valve by pushing the mounts into the original holes.
  6.  
  7. Lubricate the hose end with lubricant.
  8.  
  9. Install the hose to the EVAP canister vent valve.
  10.  
  11. Slide the EVAP canister vent valve hose clamp down on to the hose connection at the EVAP canister vent valve.
  12.  
  13. Lower the vehicle.
  14.  

Testing

The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent valve to atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge valve ON, open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent valve OFF, open, fresh air will be drawn through the valve and vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge valve into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.

Canister Vent Restriction Test

If the EVAP vent system is restricted, fuel vapors will not be properly purged from the EVAP canister. The control module tests this by commanding the EVAP purge valve ON, open, and commanding the EVAP vent valve OFF, open, and monitoring the FTP sensor for an increase in vacuum. If vacuum increases more than a calibrated value, DTC P0446 will set.

EVAP System Components

The EVAP system consists of the following components:



EVAP Canister - The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.
 
EVAP Purge Valve - The EVAP purge valve controls the flow of vapors from the EVAP system to the intake manifold. This normally closed valve is pulse width modulated (PWM) by the control module to precisely control the flow of fuel vapor to the engine. The valve will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.
 
EVAP Vent Valve - The EVAP vent valve controls fresh airflow into the EVAP canister. The valve is normally open. The control module will command the valve closed during some EVAP tests, allowing the system to be tested for leaks.
 
Fuel Tank Pressure Sensor - The FTP sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. As FTP increases, FTP sensor voltage decreases, high pressure = low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum = high voltage.
 
EVAP Service Port - The EVAP service port is located in the EVAP purge pipe between the EVAP purge valve and the EVAP canister. The service port is identified by a green colored cap.
 

Large Leak Test

This tests for large leaks and blockages in the EVAP system. The control module will command the EVAP vent valve ON, closed, and command the EVAP purge valve ON, open, with the engine running, allowing engine vacuum into the EVAP system. The control module monitors the fuel tank pressure (FTP) sensor to verify that the system is able to reach a predetermined level of vacuum within a set amount of time. The control module then commands the EVAP purge valve OFF, closed, sealing the system and monitors the vacuum level for decay. If the control module does not detect that the predetermined vacuum level was achieved, or the vacuum decay is more than a calibrated level on 2 consecutive tests, a DTC P0440 will set.

Purge Valve Leak Test

If the EVAP purge valve does not seal properly, fuel vapors could enter the engine at an undesired time causing driveability concerns. The control module tests for this by commanding the EVAP purge valve OFF, closed, and vent valve OFF, open, sealing the system, and monitoring the FTP for an increase in vacuum. If the control module detects that EVAP system vacuum increases above a calibrated value, DTC P1441 will set.

Small Leak Test

If the large leak test passes, the control module will test for small leaks by continuing to monitor the FTP sensor for a change in voltage over a period of time. If the decay rate is more than a calibrated value, the control module will rerun the test. If the test fails again, a DTC P0442 will set.

 
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