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Old 11-17-2012, 09:58 AM
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16valex 16valex is offline
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Location: New York
Join Date: Jul 2004
Posts: 3,310
Mein Auto: 530I/Stick Blown
Quick synopsis as I have posted here before. It was minus 20 degrees at work. Car parked outside. Went to go home at day's end and SES was on. Read code and it was something to do with SAP-low flow, check pump, etc. Began trouble-shooting system. Pump was getting no voltage at start-up. Traced to 50 amp fuse under passenger seat. Fuse #107. Real PITA as passenger seat really needs to slide back into rear seat area. Did not disconnect battery so when I disconnected fine stainless steel wire connected to seat that tells air bag system exactly where seat is relative to front dash, I set an air bag system code I could not clear. Removed pass. seat, removed sill plate, pulled up 1" think insulation and basically 1/2 azz accessed fuse #107, it was blown. Power in, no power out with key on. fuse is a real oddball BMW special. Replaced fuse and re-installed seat. That's when I discovered I had created air bag error by removing wire and air bag system lost calibration of where seat was. Pulled SAP to see if I could see why it had failed. Drilled out rivets, opened pump and water flowed out of pump. Obviously froze that day and fuse blew as excess current was drawn trying to get pump to run with locked rotor. Cleaned pump as well as I could and it ran on bench with old battery, but I did not trust it. Water gets into pump only one way. SAP valve fails sticking open and condensation forms in pump. Water does NOT flow from exhaust to pump through valve. Hot air from exhaust flows "backwards" to pump when pump is not running to overcome exhaust pressure allowed to flow to pump by bad valve. Condensation eventually accumulates and pump fails. Before this day, I had had NO SAP error ever. Ordered new pump, valve, all tubing (from pump to valve), new relay (salmon-colored one in white box (ECU BOX) under passenger cabin air filter, fuse, new tubing leading vacuum to valve, etc. I replaced everythying. Started car, pump ran for about 90 seconds (normal) then shut dowen and I had SES error again. Read it and it was low air flow from SAP. Tried everything then took to BMW. BMW techs charged me nada, but said they could feel strong airflow from pump-just not enough getting to O2 sensors. They said my system was absolutely fine, but I likely had blockage in heads (carbon build-up). $8000 and they said whole system was a joke just to fire cats 60 seconds faster, but BMW needed in USA only to pass government emmissions-many cars do.
I feel for you, that was one hell of an ordeal to have gone through.

if you select DSP "off" it will start on the next ignition cycle still off rather than default back to dsp "on".
Ah! OK thank you.

I just read recently about an Audi Pierburg pump that is nearly identical to E39 pump (uses same mounting ring, etc.) that is $107 NEW on Amazon.
Good to know thank you. Did you happen to catch the year and model of the Audi?
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