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Marty
Marty, ASE Certified Technician
Category: BMW
Satisfied Customers: 53152
Experience:  ASE & Bosch Certified Master Tech. Over 30 years experience.
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328i conv: I have a 1998 BMW 328 I convertible that is throwing

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I have a 1998 BMW 328 I convertible that is throwing lean codes and I have found the small one way black and white check valve of the SAP vacuum system only connected to the electric solenoid switch; the other end had no tubing attached. Ie it was hanging free. I understand there is a vacuum port on the underside of the intake manifold . How hard is it to connect this back up? Does the intake manifold have to be removed? Also. Is there a vacuum reservoir or does the manifold alone provide the vacuum?

eurotec :

Hi, and welcome. My name isXXXXX secondary air injection valve should connect to the switchover valve under the front of the manifold towards the front. It's accessible without pulling the manifold. I've attached a vacuum schematic of the system below.

eurotec :

Full Size Image

eurotec :

The diagram also shows the vacuum reservoir.

eurotec :

Please let me know if you have any questions.

Marty and other BMW Specialists are ready to help you
Customer: replied 3 years ago.
Hi Marty
I am actually referring to one way black and white plastic check valve. One end is connected to the electric switch near the front by a short piece of tubing. the other end that is suppose to attach to a vacuum source has no tube attached, ie hanging free by tubing. I have researched this and it seems it is supposed to connect to a vacuum port on the rear underside of the manifold or to a plastic y piece that also supplies vacuum to the exhaust flap. How do I access that port on the manifold underside?
Thanks, Randy
Customer: replied 3 years ago.
Hi Marty
I am actually referring to one way black and white plastic check valve. One end is connected to the electric switch near the front by a short piece of tubing. the other end that is suppose to attach to a vacuum source has no tube attached, ie hanging free by tubing. I have researched this and it seems it is supposed to connect to a vacuum port on the rear underside of the manifold or to a plastic y piece that also supplies vacuum to the exhaust flap. How do I access that port on the manifold underside?
Thanks, Randy
Customer: replied 3 years ago.
Relist: Other.
Trying to get answer sooner
Hi Randy, sorry for the wait I am in and out today. The check valve is also shown in the diagram connecting to the center of the underside of the manifold. I've attached a picture of the bottom of the intake below. The nipple should be approximately behind the throttle body. I'll be away until later this evening. Let me know if you need more help with this and I will reply when I return.

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Customer: replied 3 years ago.
Thanks Marty but the picture you sent doesn't look like the underside of my intake manifold in that I can see straight through between the intake arches from above. In your picture it looks like a cover of some kind is obscuring the view upward between the arches. I guess I'll have to get e mirror under there to see if I can find the nipple and missing rubber tube? Should there be a plastic Y that also feeds other vacuum related functions or would it only connect to the nipple you describe ?
Hi Randy, sorry for the delay. The vacuum nipple should be in the same general area as in the picture. I've attached another diagram below. The vacuum tap is where the vacuum hose should connect. Also, click here for another image showing the vacuum nipples. Let me know if you need more help with this.

Marty

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Customer: replied 3 years ago.
Thanks Marty ,
The last picture link was the clearest. Am I right in assuming the manifold will need to be removed or can I access that nipple in any other way in your opinion? Thanks for your patience. Your information was the clearest of anywhere I have been able to find after searching for days on the Internet
Hi Randy, I'm glad I could help. There isn't a lot of room under the manifold but you might be able to refit the hose from below. Otherwise I would remove the throttle body and you should be able to access the vacuum nipples. I don't think you need to remove the manifold for this.
Customer: replied 3 years ago.
Thanks Marty!