Secondary Air Injection

BACKGROUND
Secondary air injection is used anytime the catalytic converter does not warm-up quick enough after the engine has started. Air is injected through an electronically controlled aspirator upstream of the catalytic converter. The extra oxygen allows for a quick temperature rise in the converter during warm-up cycles. The Eagle Talon requires the use of the secondary air injection system due to the location of the exhaust manifold (front exhaust) in relation to the catalytic converter (under the floor pan).

OPERATION
The secondary system consists of a vacuum solenoid, a vacuum actuated aspirator valve, and hosing routed from the valve to the air cleaner and from the valve to the exhaust pipe. When the Powertrain Control Module (PCM) energizes the secondary air solenoid, vacuum is routed to the aspirator control valve. Vacuum applied to the valve opens the valve which allows air to be injected upstream of the catalytic converter.

The PCM energizes the solenoid during the following engine operating conditions:

^ Engine coolant temperatures less than 120°F - solenoid is energized for 115 seconds after the start-to-run transfer
^ Engine coolant temperatures greater than 120°F - solenoid is energized for 19 seconds after the start-to-run transfer
^ Engine coolant temperature between 140°F - 154°F - solenoid is energized during the deceleration mode

Air that is injected continuously may cause premature catalytic converter damage and will cause the O2 sensor to indicate an air/fuel ratio that contains too much oxygen (too lean). In turn, the PCM increase the injection pulse width, resulting in an increase of emissions. If the Talon's secondary air injection system doesn't function at all, the catalytic converter may not warm-up quick enough. If the catalytic converter doesn't warm-up quick enough, periods of higher than normal emissions may be detected. The catalytic converter will eventually reach operating temperatures but not as rapidly as it should.

To detect operation of the system, automatic fuel compensation is temporarily disabled and the O2 compensation control enriches fuel by adding in approximately 10%. The maximum amount of time the this portion of the test runs is approximately 18 seconds. When the downstream O2 sensor switches rich, the secondary air injection solenoid is energized. If the secondary air injection system is functioning properly, energizing the solenoid causes a shifts in the O2 sensor reading to the lean direction. This must occur in less than 19 seconds,

ENABLING CONDITIONS
In order for the PCM to begin testing the secondary air injection system, the following conditions must be met:

^ The test is run during idle only
^ Idle RPM must never drop below 704 RPM during the test
^ Engine has been running for at least 10 1/2 to 15 minutes
^ Engine coolant temperature indicates that the engine temperature is above 170° F

PENDING
The secondary air injection monitor does not run if the MIL is illuminated due to one of the following:

^ Misfire DTC
^ O2 monitor DTC
^ Upstream or downstream O2 heater DTC
^ Fuel system rich/lean DTC
^ Upstream O2 sensor shorted high
^ Vehicle in limp-in mode due to MAP, TPS, ECT DTCs
^ Vehicle speed sensor DTC
^ Secondary air injection solenoid DTC
^ Camshaft or crankshaft positions sensor DTC

CONFLICT
The Secondary air injection monitor does not run if:

^ The fuel system rich intrusive test is in progress
^ Purge monitor is in progress
^ Catalyst monitor is in progress
^ EGR monitor in progress
^ one trip misfire maturing code
^ one trip O2 monitor maturing code
^ One trip upstream or downstream O2 heater maturing code One trip fuel system rich/lean maturing code

SUSPEND
Results of the secondary air injection monitor are not recorded until the O2 monitor passes.

This monitor is performed once each trip. If the O2 sensor does not shift in the 19 second time frame during the test, the monitor fails and a maturing code is stored. The MIL illuminates and a DTC is stored if the monitor fails two consecutive trips. The message on the diagnostic scan tool appears as follows:

Too Little Sec Air
or Too Much Sec Air
Flash Code-36 J2012 Code P0411

The MIL extinguishes if the secondary air injection passes for three consecutive trips. The DTC is erased after 40 successful warm-up cycles.

Malfunction of the secondary air injection monitor could possibly be caused by problems with any of the following mechanical components:

^ Secondary air injection solenoid
^ Aspirator valve
^ Vacuum hose or air injection tube leaking