De Jeeper

If its the one that goes to the change over valve, its behind the alternator attached to the grey valve that goes to the vaccum accumulator. Its thin, black hard plastic line.

DBJoe996

Here are the vacuum lines

Wayne Walters

would that be #14 hose?

De Jeeper

No, 14 is the pressure supply line that feeds the motor from the sai pump. #28 is the vac line. Its sold in 1 meter sections from porsche. It goes from the accumulator (#6) to the change over valve(#18) to the valve to allow the sai to enter the motor.

All of these parts must work, be in tack or be connected for air to get from the pump into the motor. Its an overly complicated system.

Basically an electrical signal trips the change over valve to open, the vacuum then opens the sai air valve to allow pressurize air to flow into the motor.

If the hose before the change over valve is broken u will see it in the fuel curves, idle performance and during a smoke test. If after the c/o valve it will only leak when the sai is called to run.

In addition to the hose the c/o valve and the sai air valve can both fail but the can be bench tested.

Idaho911

My turn for this.

Is there any way to troubleshoot this other than with a shop and/or smoke machine? Are some lines more likely culprits than others?

I did a visual check, hoping to find something obvious, but the only thing I found was the hose from airbox to throttle body was not seated properly, causing a small gap. I repositioned it but have not had time to drive. Could that do it?

allcool

yes...

Any air that bypasses the MAF and enters the engine is un-metered air confusing the ecu

996love

While this statement is true, it’s unlikely to be responsible for triggering Secondary Air Injection trouble codes due to insufficient air flow.

The DME uses the oxygen sensors to check for a lean condition when the Secondary Air Injection system is functioning. If the lean condition isn’t detected, the DME thinks there isn’t enough air being injected and will trigger the Check Engine Light to illuminate.

So if you have a vacuum leak with unmetered air, the oxygen sensors will see a lean condition, making it less likely to activate these trouble codes.

I’ve experienced “false” Secondary Air Injection trouble codes plenty of times. If I start driving while the SAI system is active, the additional fuel injected (due to a cold start) enriches the air-fuel ratio enough to trigger “SAI Insufficient Flow” trouble codes.

To truly rule out this phenomenon, I’d recommend you let the car idle until the SAI system has completed its job. Of course, there are recommendations by plenty of knowledgeable people to drive the car as soon as it’s started - so that you can better prevent bore scoring.

I’ve found a happy compromise would be to let it idle only for diagnostic purposes, and make it a daily habit to drive away as soon as it’s started. If the “false” trouble codes appear only while driving, just read the code and erase it. Any cheap OBD2 scanner will work for this purpose, and you can keep it in your car indefinitely.

Now if these SAI codes appear - even when you let it idle until the SAI system has completed its process - then you’re likely to have a genuine issue with the SAI system, and will need a thorough diagnostic.

Edit: spelling