With Automatic Transmission
PULSED SECONDARY AIR INJECTION SYSTEM DIAGNOSTICS
The Pulsed Secondary Air Injection System (PAIR) reduces the emission of Hydrocarbons (HC) and Carbon Dioxide (CO) and heats the catalytic converter more rapidly. When the engine is started from cold the pulsed secondary air injection system (PAIR) introduces fresh air (oxygen) into the exhaust manifold in order to promote after burning (oxidation) of hydrocarbons and carbon monoxide. This makes it possible to increase the injection period and retard ignition, increasing exhaust temperature and activating the catalytic converter more quickly. If the pulsed secondary air injection system (PAIR) is not working emissions will increase when the engine is started from cold. To avoid this the Engine Control Module (ECM) monitors the pulsed secondary air injection system (PAIR).
The diagnostic test is divided into phases in which the various components are tested, if a fault is detected the diagnostic test is interrupted and a Diagnostic Trouble Code (DTC) is posted for that component. The main principle of the diagnostic is to interfere with long term fuel trim using the pulsed secondary air injection system (PAIR) and study what the integrator does.
1. Long term fuel trim idling and part load is blocked and Canister Purge (CP) valve control is stopped. The engine control module (ECM) starts by checking what the integrator is doing. If the integrator is at maximum the pulsed secondary air injection system (PAIR) pump is operating continuously and the pulsed secondary air injection system (PAIR) valve is leaking, diagnostic trouble code (DTC) EFI-442 Pulsed secondary air injection system (PAIR) EFI-446 pulsed secondary air injection system (PAIR) valve and EFI-448 pulsed secondary air injection system (PAIR) pump will be stored.
2. The pulsed secondary air injection system (PAIR) pump is started and the pulsed secondary air injection system (PAIR) pump is kept closed. The integrator should remain unchanged, if it rises above a certain limit within 6 seconds this indicates a leaking pulsed secondary air injection system (PAIR) valve and diagnostic trouble code (DTC) EFI-446 Pulsed secondary air injection system (PAIR) valve is posted.
3. The pulsed secondary air injection system (PAIR) valve is opened and the pulsed secondary air injection system (PAIR) pump continues to operate. The integrator should now rise above a certain limit within 6 seconds, if this does not occur this indicates that the pulsed secondary air injection system (PAIR) pump is not operating or that the pulsed secondary air injection valve has not opened, diagnostic trouble code (DTC) EFI-448 Pulsed secondary air injection system (PAIR) pump is posted.
4. The pulsed secondary air injection system (PAIR) pump is shut down, the pulsed secondary air injection system (PAIR) valve is closed and long-term fuel trim idling and part load blocks are released. The diagnostic test is concluded.
To carry out the diagnostic test:
- Engine temperature must be between -12 - +50°C when the engine is started
- No permanent faults must be posted for the throttle position (TP) sensor, either of the heated oxygen sensors (HO2S), the canister purge (CP) valve, battery voltage, fuel trim, the pulsed secondary air injection (PAIR) solenoid, pulsed secondary air injection (PAIR) pump and the engine must not be misfiring
- Engine idling
- Speed lower than 4 km/h
- The integrator must not be at its minimum level
- Engine temperature must not exceed 103°C.
The diagnostic test will not start until 10 minutes after the engine was started when all conditions have been fulfilled, it then takes a maximum of 20 seconds. If the diagnostic test is interrupted it will commence again the next time that all conditions are fulfilled, although at the earliest 11 minutes after the previous attempt. The engine control module (ECM) makes a maximum of 2 diagnostic attempts (diagnostic attempt = pulsed secondary air injection system (PAIR) pump has started) in any one journey, if the diagnostic test is interrupted both times the engine control module (ECM) will not make another attempt until the next time the engine is started.