Secondary air intake code - 986 Forum

Fuzzuki · 04-30-2018, 01:50 PM

My car keeps showing a code for the secondary air intake.
I know it means that the blower motor is not functioning.
But I do hear it working most times I start the car.

After I clear the code, it is fine for weeks, but then when I come off the highway, the secondary air fan will not be functioning and the idle dips and stumbles and recovers, then the code comes back showing check engine again.

Is there a sensor telling this fan when to work?

When is it supposed to work?
I know it is supposed to run on cold start.
But when is it to be running other times???

I know this fan is working. but sometimes it does not come on at the correct time????

HELP.

NewArt · 04-30-2018, 02:03 PM

The SAI fan only runs at cold startup. Your problem is more likely related to an air leak in one of the hoses. Please remember to post the code here as this will help us in finding a possible solution.

911monty · 04-30-2018, 02:06 PM

Quote:

Originally Posted by NewArt

The SAI fan only runs at cold startup. Your problem is more likely related to an air leak in one of the hoses. Please remember to post the code here as this will help us in finding a possible solution.

The fan runs for 90 seconds on cold startup. It will run again to perform a system check at first idle period. This can be at the first stop 2 blocks down the road or after an hour on the interstate if you never idle after cold start. It will run the system test a few times before it sets the CEL.

thstone · 04-30-2018, 03:01 PM

There is no sensor (per se) that tells the air pump when to run. Instead, the air pump is commanded on by the ECU depending on coolant temperature (for cold start operation) and engine rpm (for pressure test at idle).

Use your Durametric to manually turn on the SAI pump. That should verify that the pump and all of the electrical connections are good. And if the pump operates manually, then it should operate properly when commanded by the ECU (whether cold start or pressure test).

The most common problems are hose leaks and inop valves.

What CEL code are you getting? That will help us point you in the right direction.

911monty · 04-30-2018, 03:26 PM

Quote:

Originally Posted by thstone

There is no sensor (per se) that tells the air pump when to run. Instead, the air pump is commanded on by the ECU depending on coolant temperature (for cold start operation) and engine rpm (for pressure test at idle).

Use your Durametric to manually turn on the SAI pump. That should verify that the pump and all of the electrical connections are good. And if the pump operates manually, then it should operate properly when commanded by the ECU (whether cold start or pressure test).

The most common problems are hose leaks and inop valves.

What CEL code are you getting? That will help us point you in the right direction.

The system check uses the 02 sensors to detect a lean condition when the SAI pump is running. It will then set the MIL code for the bank/banks that are not working.
If a Durametric is available you can monitor the 02 sensors and start the SAI pump to monitor function. Failure points are the air change over valve, the electric switch, vacuum tank and as Jaeger so graphically posted the ports in the heads themselves.

Stroked & Blown · 04-30-2018, 06:14 PM

If it ends up being the pump, vacuum canister, or valves, I have a set that I recently pulled from my manual 2.5L at 47k miles.
Works fine, just dropping weight.