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The primary issue with the SAP is caused by two things:
- the check valve in the vacuum system needs to be replaced occasionally
- the solenoid that controls the air flow to the SAP valve needs to be removed, and cleaned with electronic parts cleaner
These two items are the source of the issue in most cases. The solenoid actuates the valve to open it. When it deactivates, the vacuum in the line needs to bleed off rapidly, to close the valve. The check valve in the vacuum line to the solenoid is what causes the vacuum to bleed off. If the SAP valve does not close immediately, because the vacuum is not bleeding off, the valve stays open, and exhaust gasses blow through the valve, and into the pump. This will kill the pump eventually.
This Seafoam procedure does not address the root cause. It simply cleans out the valve, and the cycle starts again. If you pull off the hose from the pump to the valve, look inside the hole, and see soot from engine exhaust blowing past the valve, then you need to replace the check valve, and clean the solenoid. Replace the rubber hoses as well. If the system is working normally, you should see a nice, clean valve when you look inside there. Anything else is a sign of a larger problem that will eventually kill your SAP.
Another sign of a failure of the vacuum actuation is if your hose from the SAP to the valve is degrading. It should be firm, and hard to compress. Check the large vacuum line from your brake booster for reference. They should feel the same. If it is degrading, it is because of exhaust gasses blowing by a SAP valve that is not closing in time to prevent exhaust gasses from back flowing into the pump. I have seen many people advise replacement of the hose, but a degraded hose is a symptom of another problem.
The fix is fairly cheap, but a bit labor intensive, due to the location of the solenoid and the check valve. If you want to save your $400 SAP pump, I would advise dealing with the problem, rather than treating a symptom (dirty SAP valve).
Also, it is much easier to just remove the valve, and clean it with brake cleaner, rather than pouring Seafoam in your engine. You can also access the port in the head with the valve off, and clean it as well. BUT, you need to deal with the root cause of the problem, in addition to cleaning the valve.
Hi, thread revival time!

I am trying to figure this out because I was having the cold start knocking issue as well among other things like my car shutting off randomly with no codes thrown(I think I narrowed this issue down to the cam shaft sensor).

Anyway getting back to the subject at hand. I am trying to understand what this user said because i did the seafoam and it worked, BUT!
I also looked at my hose and it has cracks within it which this user indicates is because of other problems. So in order to understand what he is say I have attached an image with the parts I believe he is referring to and I have a couple of questions.

1. When he says "the check valve in the vacuum system needs to be replaced occasionally", does he mean part #1 or part #6?

2. When he says "the solenoid that controls the air flow to the SAP valve needs to be removed, and cleaned with electronic parts cleaner", does he mean part #5?

Thanks
 

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1. When he says "the check valve in the vacuum system needs to be replaced occasionally", does he mean part #1 or part #6?

2. When he says "the solenoid that controls the air flow to the SAP valve needs to be removed, and cleaned with electronic parts cleaner", does he mean part #5?
For question #1, I believe item #1 is the answer, but before this is changed, it should be tested.

For question #2, the answer is #5, however, I would not worry about removing the item to clean it.

If you have a SAP problem, suggest you check out these threads for some light reading:

http://forum.e46fanatics.com/showthread.php?t=1041726

http://forum.e46fanatics.com/showthread.php?t=1023149

http://forum.e46fanatics.com/showthread.php?t=965526

http://forum.e46fanatics.com/showthread.php?t=1052605

http://forum.e46fanatics.com/showthread.php?t=1074847

http://forum.e46fanatics.com/showthread.php?t=1074573

http://forum.e46fanatics.com/showthread.php?t=106959

http://forum.e46fanatics.com/showthread.php?t=1074847

http://forum.e46fanatics.com/showthread.php?t=106959

http://forum.e46fanatics.com/showthread.php?t=1078986

http://forum.e46fanatics.com/showthread.php?t=1096889

http://forum.e46fanatics.com/showthread.php?t=1100895

http://forum.e46fanatics.com/showpost.php?p=17091432&postcount=28

http://forum.e46fanatics.com/showpost.php?p=17091517&postcount=29
 

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i don't have the newsletter but most of the bavauto stuff is still online in youtube and at https://blog.bavauto.com/.

and this thread has the missing photobucket images as well. so frustrating.
Yea, really harms the value of all of this work when linked images/files stop working. It's like a library burning down or something.

Best I coudl find was this. Is this the same as the linked PDF?
https://blog.bavauto.com/12072/bmw-secondary-air-system-fault-code-diagnosing-how-to-diy-obd-ii/
 

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//Binary is in my DNA
2002 BMW 325i
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i don't have the newsletter but most of the bavauto stuff is still online in youtube and at https://blog.bavauto.com/.

and this thread has the missing photobucket images as well. so frustrating.
Curious what browser you are using? There's no missing photos on this thread for me using Chrome and Photobucket Hot Link fix.

 

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//Binary is in my DNA
2002 BMW 325i
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Yes, the pictures I show are from post #2. Only 3 pictures though but no broken links. Photobucket Hotlink fix looks like a plug in for Chrome and Firefox. Nothing on Safari if you are using Mac :dunno:
 

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Advice on vacuum hose needed

Hi all,

Recently I replaced my VCG and inadvertently broke the vacuum hose running from the SAP check valve back to the electric valve on the intake. Patched it with some heat shrink for a few weeks which worked as a temporary fix since I didn't get any codes popping up. I just got around to replacing the hose this last weekend. I couldn't find any 3.5mm ID vacuum tubing in town so went with a 1/8" ID silicone hose (3.175mm). It fit snugly (not too snug) and completely onto the respective nipples and thought I had it fixed.
Immediately after first start the SES light came on, with codes 0491 & 0492 which has never happened once in the last 3 years I've had the car, even when it was heat-shrink-patched.
So my question is, could that small of a difference in I.D. in the hose cause it to read as insufficient flow? Or is it possible that just the act of switching the hose and it getting proper flow has let the computer be able to read a pre-existing problem?
I did notice on quickly poking around that the hose between SAP unit and check valve is getting old and showing some signs of dry rot near the bottom. I took off the SAP end and it was pretty clean inside, with a very light dust coating inside.
Edit: Also, I've been hearing more noise from the SAP unit the last few months on cold start, it's pretty whiny now but I'm not sure if that's a sign of it wearing out or a clogged outlet somewhere that it may be working against.
I really don't want to go down a rabbit hole with this this weekend as I'm planning on overhauling the CCV system already.
Thanks in advance Guys and Gals
 

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Hard to say but that kind of air flow restriction could easily throw a code. As I came to appreciate with the SAP system, it's non-critical and not worth spending time on it. It's very finicky to the point that codes come and go depending on many factors, including weather.

Hi all,

Recently I replaced my VCG and inadvertently broke the vacuum hose running from the SAP check valve back to the electric valve on the intake. Patched it with some heat shrink for a few weeks which worked as a temporary fix since I didn't get any codes popping up. I just got around to replacing the hose this last weekend. I couldn't find any 3.5mm ID vacuum tubing in town so went with a 1/8" ID silicone hose (3.175mm). It fit snugly (not too snug) and completely onto the respective nipples and thought I had it fixed.
Immediately after first start the SES light came on, with codes 0491 & 0492 which has never happened once in the last 3 years I've had the car, even when it was heat-shrink-patched.
So my question is, could that small of a difference in I.D. in the hose cause it to read as insufficient flow? Or is it possible that just the act of switching the hose and it getting proper flow has let the computer be able to read a pre-existing problem?
I did notice on quickly poking around that the hose between SAP unit and check valve is getting old and showing some signs of dry rot near the bottom. I took off the SAP end and it was pretty clean inside, with a very light dust coating inside.
Edit: Also, I've been hearing more noise from the SAP unit the last few months on cold start, it's pretty whiny now but I'm not sure if that's a sign of it wearing out or a clogged outlet somewhere that it may be working against.
I really don't want to go down a rabbit hole with this this weekend as I'm planning on overhauling the CCV system already.
Thanks in advance Guys and Gals
 

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Hard to say but that kind of air flow restriction could easily throw a code. As I came to appreciate with the SAP system, it's non-critical and not worth spending time on it. It's very finicky to the point that codes come and go depending on many factors, including weather.
Thanks for the input. Makes me want to look into deleting the whole system as I don't have to worry about passing emissions in my state!
 
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