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Loud secondary air pump

30133 Views 65 Replies 12 Participants Last post by  vaboxr
My 97-528 SAP is kind of loud compares to my 02-530.
It's a fast loud thumping sound.
I think the air passage may have been clogged, but then again this maybe normal for 528.
How's every 528 SAP sound in the morning? Thanks for the feed back.
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Just wanted to say that I'm glad you solved your PITA SAS/SAP problem, Alex.

Just for clarification the SAS system pumps air and hence oxygen directly into the exhaust manifold and exhaust system to help the CATs light off quicker thereby reducing cold start emissions sooner. Since the upstream O2's are in open loop during cold start and warmup, they are used by the ECU to detect a lean mixture which means that the SAS system is working. If the O2's detect a richer mixture, they indicate low or no flow from the SAS and set fault codes accordingly. Once the O2's go into closed loop, the SAP has shut off as has the vacuum to the check valve and the SAS job is done and the upstream O2's go back to their normal job of feeding the ECU info for mixture control.

WOW, that sure seems like alot of trouble to clean up the exhaust a few minutes (seconds) early. I guess every second counts. Lol.
Yeah! I thought you had solved your SAS chu, chu problem when you replaced the IM gasket, but I guess it was not to be.

Are you going to repair your old pump using CNN's DIY on Bimmerforum? It would be nice to have a spare pump around. Of course that's assuming that a ruined bearing is what's wrong with the pump.
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