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Loud secondary air pump

29495 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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John, thank you and very informative explanation. :thumbup:

To make a long story short the main culprit of my problem was low vacuum from the intake that caused a partial closed air valve and thus created the thumping sound from the very beginning.

Since I had the intake manifold gasket and all the hoses under the IM replaced back in June, this car has come alive;)
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.
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.
As I mentioned in other threads, the Volvo people have bypassed the SAS system using a diode.
If some geniuses from this forum can figure out how to do this on the E39, it'd be golden!

Here is the Volvo trick:

It would resolved the chu chu sound had the SAP didn't died on me.

johnstern;7122440]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.
Nah! Not now, maybe someday. The old one has only been in there a year and died prematurely!
cn90, I don't think you can simulate our SAS system by some simple diodes. It needs a few more logics to the circuit.

Here are some pics of the SIM from an E36











As I mentioned in other threads, the Volvo people have bypassed the SAS system using a diode.
If some geniuses from this forum can figure out how to do this on the E39, it'd be golden!

Here is the Volvo trick:

Attachments

seafoam effect on cat

The thread seems to go for using seafoam - can't that process affect the cat? I just went with an OEM cat on my wife's 97 E52 and I'd hate to ruin an $1800 part (they are SO proud of them). Thanks
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