Secondary Air Injection Pump

[SlowJoe]

I have a 99 M3. 115,000 miles.

When I start the car, for the first minute or two, a sound comes from under the hood that sounds like a squealing pig, then it stops.

I was told it is my 'Secondary Air Injection Pump' and it would have no affect on its drive-ability but I likely wouldn't pass my next emissions test.
Does this sound reasonable?

Can these pumps be bought used or rebuilt? Any suggestions?

ETA: I see they are available on eBay for ~$50 give or take. Any thoughts on these?

Thanks in advance.

[TostitoBandito]

Yes, that sounds right and is pretty common. It's also correct that it has zero effect on your car. All it does is inject air into exhaust after startup while the engine is cold for emissions reasons. Depending on how your state tests, you may still pass emissions since your car will have been running for a while when they test. The pump is also probably still working, just noisy. You'll get a check engine light and codes if it actually fails.

Here's a replacement DIY:
https://www.bimmerforums.com/forum/s...cylinder-cars)

I'd just leave it alone unless it actually fails, and then I'd either do a delete or replacement depending on what I can get away with for emissions in my state.

[propcar]

mine died, I removed it, plugged the SAP hole with a OEM block off plate, and tuned out the CEL with software along with a performance re-map by TRM.

[Ateyourv8]

You can unplug it before a cold start and see if the squeal goes away to make sure its the SAP indeed making the noise.
As mentioned above, its easily removable and the port blocked off. But instead of getting a tune, you can either buy or make a SAP simulator, or you can just leave it unplugged and deal with the CEL

[SlowJoe]

Thanks for the replies. Much appreciated.

[gpeterson]

If you unplug the pump (even temporarily) you should disconnect & cap the vacuum line that runs to the valve. If you don't there will be hot & moist exhaust gas flowing into the pump which will accelerate its death. If you do replace the pump make sure the valve is sealing correctly for the same reason.