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-   -   Secondary Air System Issues (http://www.bimmerfest.com/forums/showthread.php?t=672916)

Richey 01-28-2013 01:11 PM

Secondary Air System Issues
 
I got an SES with codes P0491 & P0492 (Secondary Air System). I took it to a local shop that I've used before and somewhat trust to diagnose this and fix some other minor things that I didn't have the time to do.
Verdict: bad air pump. It was getting power; just not working. Fix: New Air Pump.

3 Days later, SES light with same codes. I verified the air pump was running...I heard it running. I had searched the forum and put my money on a bad air check valve. I ordered one and installed it myself. The vacuum hose from the air check valve to the solid plastic hose running along the side of the engine looked ok so I didn't replace it. Cleared the codes.

2 Days later, SES light with same codes. I climbed in the engine compartment and replaced two of the back vacuum hoses. They did seem pretty brittle. Hopefully this was it.

2 Days later the light came back on. Dammit man!

My question is: while I had the hose of the air check valve, I blew into it and air came out from behind the engine. This is before I replaced the back hoses so I thought it was obvious I had a leak. After replacing the hoses, I could still do this. Is this right? Should the system be closed or does the electric check valve keep the system open until it gets a signal to close the system to create the vacuum to open the air check valve?

The electric valve is about all I have left to replace unless the system is working and a sensor went bad. Or I got a faulty air check valve...I really hate when new parts don't work.

Thanks in advance for any help.

Stone Roots 01-28-2013 01:30 PM

Ill be watching too - Im getting the same codes and getting the whirling sound at cold start. I just dont trust taking my car to mechanics. Always seem like they fix something and magically something else goes wrong in the immediate future....

Fudman 01-28-2013 01:48 PM

The electric valve is all that's left to replace. I do not believe that you can blow into the vacuum pipe and hear air coming out at the electriv valve (that end should be closed). I suspect the valve is fine and you have a crack in the vacuum tube between the valve and the plastic vacuum pipe. Replace it although access is not easy. Save your old pump and valve as they may still be good.

Richey 01-28-2013 01:49 PM

Whirling sound is probably good
 
At least it sounds like your air pump is working.

Richey 01-28-2013 01:55 PM

Fudman
 
I replaced that bit of tubing. Along with the piece from the electric valve to the little cylinder in-line valve. I really couldn't tell where exactly the air was coming out of. Hard to blow and search at the same time. :yikes:


If it's supposed to be closed when not running, it sounds like the electric valve might be bad.

Steve530 01-28-2013 03:29 PM

Did you replace the hose that goes to the intake manifold?

Richey 01-28-2013 03:38 PM

Not that one
 
I didn't replace the hose from the inline check valve to the intake manifold.
It looked different and in better shape than the other pieces...almost like it had been replaced before.

I'm pretty sure the place where air was coming out was around the electric valve. I crimped the hose before the electric valve and couldn't blow air through. I thought I crimped the hose after the valve and air was still coming out. Hence the question if the system supposed to be closed and if the electric valve might the the culprit.

Steve530 01-28-2013 04:03 PM

2 Attachment(s)
AFAIK, the valve should be closed when it is not energized. My assumption is that the electric valve is there so that the ECU can control the supply of vacuum to the SAP valve.

If it has failed open, the vacuum should be supplied to the SAP valve all of the time. You should see a vacuum at the SAP when the car is running. Of course the valve could have broken so that the vacuum is not passing through.

That valve is in a difficult place to reach. IIRC, it's mounted with a clip on a bracket. I think you push the tab toward the firewall to remove it, but I'm not sure about that.
It may be easier to remove the bolts that hold the plate to the manifold. I've attached a couple of pictures.

http://www.bimmerfest.com/forums/att...1&d=1359418882

http://www.bimmerfest.com/forums/att...1&d=1359418882

Richey 01-28-2013 04:57 PM

That's it.
 
At least from what I could see looking upside down in a mirror.

I didn't know if those two torx bolts were the only thing holding that bracket and if the valve was the only thing on that bracket or not. I didn't want to take something apart that I shouldn't.

Steve530 01-28-2013 05:17 PM

Quote:

Originally Posted by Richey (Post 7344318)
At least from what I could see looking upside down in a mirror.

I didn't know if those two torx bolts were the only thing holding that bracket and if the valve was the only thing on that bracket or not. I didn't want to take something apart that I shouldn't.

Check this link.

Richey 02-08-2013 10:17 AM

Just thought I'd come back in and update the solution to my problem.

Even thought the air pump was replaced and I confirmed it was running (at least the one time I checked and listened for it), the issue was the connection to the air pump. The end of the electrical connector was ok and not noticeable deteriorated, but the ground wire was "rotten" up from the connector and the pump wasn't getting a good connection and therefore not running all the time.

Replaced the connection and all is good now. Just another thing to check...especially for intermittent problems.

Part numbers 61138352390 & 61130007569

I'm still glad I took the time to replace the back vacuum hoses. They would have caused issues before too long.

BentValve 02-08-2013 10:53 AM

There's a salmon colored relay in the DME that has been known to fail. This is cheap compared to the other components of the SAP.

Fudman 02-08-2013 11:16 AM

Quote:

Originally Posted by Richey (Post 7368360)
Just thought I'd come back in and update the solution to my problem.

Even thought the air pump was replaced and I confirmed it was running (at least the one time I checked and listened for it), the issue was the connection to the air pump. The end of the electrical connector was ok and not noticeable deteriorated, but the ground wire was "rotten" up from the connector and the pump wasn't getting a good connection and therefore not running all the time.

Replaced the connection and all is good now. Just another thing to check...especially for intermittent problems.

Part numbers 61138352390 & 61130007569

I'm still glad I took the time to replace the back vacuum hoses. They would have caused issues before too long.

Thanx for posting the resolution. It seems that the cause of many electrical failures is a loose connection to ground or power or looseness of a battery connection. Good to see you get it fixed.

diggyd357 02-08-2013 03:08 PM

+1 I love happy endings !!!!

LalaRay 02-08-2013 11:40 PM

This is to many problems it could be for these codes

540iman 02-09-2013 08:59 AM

Hopefully, you have saved your old pump and valve. Likely the mechanic that changed your old pump tossed it, but maybe not. FYI, these pumps are re-buildable and easy to take apart and inspect for moisture in them. If they are dry, I usually just lubricate, clean the foam filter, and back on the car. The valve can be soaked in the stuff Autozone sells in a 1 gallon can sold as carb cleaner (have a gallon of it in garage, but forget who makes it). If you go to Autozone and ask for the 1 gallon can of carb cleaner with the built-in basket, they will know. Costs $25. Just soak valve overnight. This stuff has been proven to remove carbon build-up and I can attest that it really works! Will not damage your valves inner parts, but will remove any carbon that can keep the valve from closing fully which is the cause (usually) of the Piersburg pump failing from water rot or water freezes inside pump causing it to lock-up. Just some random info on the SAP system.
Pump is actually being used in an "over-speed" condition to push as much air as it does (as the O2 sensors need to see). If the pump were to run for longer than about 5 minutes, it will burn-up and be toast. This is also why the entire pump electrical is fused at 50 amps
thru fuse 107 which is a bitch to get at under passenger seat rug. 50 amps to salmon-colored relay in ECU box under pass. side cabin air filter. ECU sends 12v to relay for a "normal" ~90 second cycle on cold start-ups. Relay handling about 34 amp draw of motor often gets contacts "welded" closed causing motor to run "forever" which in reality is about 5 minutes and then it is shot and may take the 50 amp fuse with it if the motor encounters "rotor lock" before the windings gets so hot they short.

Water gets to the motor NOT from moisture in the exhaust going past a partially-stuck-open check valve, but because of the heat in the exhaust stream getting past a check valve that is not fully closed and the motor shuts off after the 90 seconds. Now, there is no air flow from the pump to "push the exhaust gases back" and the gases are now free to flow with no pump air flow to stop them back into pump which is cold and simply forms condensation inside the pump. Over time, this small amount of water becomes a small pool of water in the pump. Left outside overnight in a cold climate and now you have a frozen pump waiting for you to get in and start car. 90 seconds of current flow to a frozen pump causes pump failure, possible relay welding due to excess current draw or fuse 107 blowing.

When replacing pump, always replace valve as well or you are really taking chances.

Last common problem which happened to me on my personal car was like this. Replaced my frozen pump, relay, replaced fuse 107, valve, and hose from pump to valve. Entire system new and working properly, but still getting low air flow bank one and two errors. New pump out of the box had ever-so-slightly less power than old pump when it was working. Lines from valve to heads and heads had CBU (carbon build-up). There was enough carbon in the air path to no longer satisfy the O2 sensors which must see the exhaust stream go lean (enough) while pump is adding air ahead of convertors to exhaust stream. Two fixes-there are no "simulators" or "sims" to fool this system. $8000 repair where BMW gun drills your heads and replaces lines to get better air flow to exhaust. $300 fix (for me) which was purchase of Powerchips modified ECU which is generally bought for a supposed HP gain or performance gain, but they also can change your USA software to Euro software that does not need to see as much air flow at the O2 sensors to be satisfied. On a Euro car, if SAP system fails partially, they get no SES! Just sets a code that will only show during a scan. If you opt for the Euro software for SAP when purchasing a Powerchip, you will no longer see SES as long as all the components are installed properly and some amount of air is flowing. It basically opens up the parameters of air flow necessary to satisfy the O2s and ECU and our local emmissions people! Sorry to be so wordy, but in case there are others wanting to understand or are having similar issues.


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