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Old 06-12-2012, 06:20 AM   #1
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Secondary Air Pump Operation

Most likely the forum has discussed this but I cannot find an answer to my specific question.

Does anyone know the trigger points for when the secondary air pump operates or not?

My understanding is the pump turns on and runs for a minute or so when two conditions are met: 1) the engine is cold and 2) the outside air temperature is below a certain value. Is this true?

Does the pump have to meet both conditions at the same time or is one enough? My pump runs whenever the engine is started cold regardless of the outside temperature.


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Old 06-12-2012, 07:25 AM   #2
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Not sure about your car as you didn't specify model year. On the newer cars (987), input signals for the SAI pump to run include coolant temp, intake air temp, altitude, and if the front O2 sensor is operating to allow closed-loop operation. All these values are part of the algorithm the DME uses and when it figures out when and how long the pump should run.

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Old 06-12-2012, 03:59 PM   #3
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My car is a 2001 S. The O2 sensors are brand new.
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Old 06-12-2012, 04:20 PM   #4
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Originally Posted by Bentley, section 02-11
The Boxster engine is equipped with a secondary air injection system which uses an electric pump to force fresh air into the exhaust system upstream of the catalytic converter during engine warm-up. By providing extra oxygen to the unburned fuel in the exhaust, hydrocarbons oxidize and carbon monoxide combines with oxygen to form carbon dioxide and water. The air injection pump stops within a specified timed interval.
Bentley doesn't go into any other detail about the SAI operation, but it seems to be tied to when the engine is started and it's below normal operating temperature, and runs for approximately 60 seconds. And it doesn't seem to care what the outside air temperature is.

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