Secondary air pump

[Sputter]

The secondary air pump shuts off at warmup?

Mine seems to make a "winding down sound" when I shut the car off. Which tells me it's staying in operation.

Would this be a sign of it failling? No code is being thrown.

How many amps would the pump draw if it is staying on? I'm wondering if could run a battery down at low rpms (2-2.5kish). I know the car really doesn't charge much at low rpms.

Thanks, Jim

[Loren]

Per Porsche's 199 Tech Book...

"Auxiliary Air Pump

To reduce pollutants contained in the exhaust gas during the warm-up phase and to achieve the emission limits of the roll test in the USA, USA vehicles have a secondary air system. For this reason, an electric air pump has been mounted on the left-hand side of the engine compartment (Carrera). This pump is activated by the DME control unit and blows the additional air through air ducts to the discharge valve. A pneumatic switching valve which is closed when the secondary air system is inactive thus preventing the flow of additional air is installed between the air pump and the discharge valve.

Functioning

If the engine is started in a temperature range between minus 10.5° C and plus 45° C, the secondary air system is activated for a period of time dependent on the start temperature (min. 50 seconds, max. 179 seconds).

The secondary air system is only activated if the following engine-related operating conditions apply:

- Engine load (TL) between 0.7 ms/rev, and 4.7 ms/rev.

- Air mass (ML) not greater than 300 kg/h

- Engine speed between 680 rpm and 2,800 rpm

- Altitude adaptation factor greater than 0.76 corresponding to less than 2,400 meters above sea level."

[rsfeller]

The secondary air pump shuts off at warmup?

Mine seems to make a "winding down sound" when I shut the car off. Which tells me it's staying in operation.

Would this be a sign of it failling? No code is being thrown.

How many amps would the pump draw if it is staying on? I'm wondering if could run a battery down at low rpms (2-2.5kish). I know the car really doesn't charge much at low rpms.

Thanks, Jim

Jim,

Are you sure you know the sound of this item? I only question your concern as my is very noticeable when running and there would be no mistaking it and not just a notice when it is "winding down".

I see you questioned on the other post about voltage the time Nexus's car died. Are you concerned about your power output and battery? Do you have a reason to be concerns?

My experience is that below 2800rpm there is still sufficient voltage generated to charge the system and offset lights, stereo and electric cooling fans. I doubt the SAP out "amps" the fans when the AC is on. I am curious to what other concerns you have in regard to the voltage?

Also, if the SAP is truly running I would suspect the MAF if I understand it's purpose correctly. (correct me if I"m wrong here). Looking at the info Loren supplied the system most likely to fail here is the all to common MAF. Are you experiencing any dead spots in your power band? (early signs of MAF concerns from what I read).

[Sputter]

I got my wife to turn on/off the boxster while I hunted for the sound. Coincidently it started just after I swapped out the ignition switch.

It was the powersteering pump. (not one of fluids I check on regular basis).

It did sound like it was on the passenger side,,,really.lol

Now i'm seeing a drop on the battery down to 11.5ish volts while the car is running at idle. Since it should actually be higher with the car running i'm leaning towards the alt/vr. I should be happy that's not cooking the battery ;)

Nothing to do now but to pull it and see what's failed on it.

Thanks, Jim

[rsfeller]

It can be very hard to determine what side a sound is really coming from on any car when you are in the driver seat. I have had many a wheel bearing behind me or a C/V or inner driver perplex me up front.

I did feel the secondary air pump was most likly not the issue, they are so loud and noticable with the top down and usually work like they should or don't work at all.

I am not sure where you live, how much you drive the car and if other factors may play into it but due check your battery connections before passing judgment.

Make sure the terminals are clean on the battery

Inspect the connections at the altnerator too (salty area can do major damage)

How old is your battery?

Keep in mind it's easier to pull a battery and run it up to FLAPS then the alternator and since I have been lurching on this site I have seen many a battery failure and fewer alternators. The battery run downs on these cars seems to have a bigger effect on systems then other cars I have driven.

Now with all that said have you driven you car around and then come back and check the voltage at idle?

Is it still 11.x?

Also keep in mind that 90% of all voltage regular failures (I have seen) tend to occur with low voltage. I think I had one boat that went the other way and was running 18.x volts before we noticed it! Luckily it did not damage any systems or toss and fuses or wires.

I was asking if the VR was internal or external on these alternators as I have seen seen a few posters mention bad VR (but not failed alternators) and was wondering if the VR can be removed with the alternator still in.

[juniinc]

VR!

[Sputter]

I'm still working on problem.

I drove it this am about 17mins or so mixed driving from 50km-90km (speedwise) headlights/with my DRLs on (my drl is my foglights).

It was parked for 4 hours. I drove it home same as above but no headlights just the DRLs.

I did a voltage check on the battery after those drives and battery showed 12.28 car off or 11.54 with everything on and car running. (air/radio/headlights etc)

The brief "winding down noise" is still present. (driverside).

A question.

Could the starter solenoid be keeping the starter engaged to be drawing power and causing the "winding down" sound?

Jim

[rsfeller]

I wouldn't be the one to stick out my head and see yes on this, but it sure seems posible!

This starter is known to stick/drag and cause a funny sound when starting. I know becuase mine does it when cold. So any failure trend is posible and I have heard (with other cars) people talk about starter-run-on.

I would guess from the amps being pulled it would over heat and burn-out but that is just a guess. One reason they tell you never to run a starter very long is due to this reason. So I would guess you would have killed it or the wiring (melted it) by now from the amps.

As you may know one is usually looking for 13+ volts when car is running with low system draw so the VR still sounds like the most likely cause but that unique sound needs to be figured out!

[Sputter]

The "winding down" sound was the alternator. A combo of bearings/freewheeling pulley it seems.

Jim