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roman.lysiak

Vacuum bib on the lower right side of throttle body.

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I’m hoping this bib not being capped is the solution to my rough and lean engine.

 

Anyone ever see this vacuum

Bib located on lower right side of the throttle body. I have a 73tii us spec and I know these were using mechanical advance on the dizzy. When did they start using vacuum advance on the dizzy advance? Or what is this for. I’ve capped it now. Can’t wait for the morning to try it out. Like opening Christmas presents. Time for bed.

 

 

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(edited)

You don't want to cap that off, it connects the throttle body to the breather hose between the motor and the brake booster.

If disconnected, you'll have all sorts of rough running devilry (ask me how I know).

 

image.thumb.png.8f091cf459d7d69d2445e5f5f1bc1b02.png

 

Somebody more expert than me could comment, but note that this bib sits behind the butterfly, so vacuum from there is likely helping to pull fuel in during cold start among other things, and it will cause a vacuum leak if left open on both the bib and the hose. 

IMG_2568.thumb.JPG.f6b3fb818dc9c8859b62542d848c61e8.JPG

 

The breather hose also has a plastic nipple inserted into it. 

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https://www.wallothnesch.com/en/motorteile-kuehlung/bmw-1502-2002-turbo/katalogbild-11-24.html

https://www.wallothnesch.com/en/breather-hose-for-2002-tii-11-24-02.html

Perhaps your hose to the TB is missing, so this connection does not appear obvious.  It's hard to see with the runners in place.  A looong pair of hemostats is helpful for making this hose connection.  And make the hose connection long enough to put some positive pressure between the two, as it can pop off unnoticed (again, ask me how I know!).

Edited by Swiss 2002Tii
additional info

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If you are waiting for parts to arrive, you can tune the air/fuel mixture with a plug in that inlet.  Later, when you connect it properly (as per @Swiss 2002Tii) you will adjust your mixture again to compensate for the extra air being sucked in from the breather hose.

 

Trick:  Remove runner #3 for easy access to that hose connection.  4 nuts (and washers).

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(edited)

No.  That inlet is for the line from the catch can in the trunk.  Should be connected or you might experience fumes in the trunk.

Edited by PaulTWinterton
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AFAIK the reason for the hose is emissions related.  Easiest to plug the inlet until you can connect it correctly. 

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Yes I do have fuel smells in the trunk. Another topic to go into later. That little outlet on air intake is really close to where the hose btw the valve cover and the air. Would it affect anything if I just attached the small hose from TB bib to this point?


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6 hours ago, roman.lysiak said:

Would it affect anything if I just attached the small hose from TB bib to this point? 


It will affect the tuning.  That is a direct draw from outside air.  Not what you want.  It is meant to draw oily air from the valve cover only.

 

Block it or connect to the breather hose.  Find and attach the hose from the trunk back onto the air cleaner.  Then you're golden. 

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(edited)

Paul, was that line from the catch can to air intake a later mod for emissions? I don't have that on my EU '72 Tii, just a line from the filler neck to the trunk floor.  The PO for mine also ordered the FSO (Fuel Smell Option).  

Working on that in a separate thread! ?

Edited by Swiss 2002Tii
spelling

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(edited)
3 hours ago, Swiss 2002Tii said:

Paul, was that line from the catch can to air intake a later mod for emissions?

 

Not that I know of.  Don't you have the inlet port on your aircleaner?  4mm O.D. I think.

AirCleanerReturnHOse.jpg.bccd66f991f1a661a3501afad152baef.jpg

I will look, but I don't think I have the hole in the trunk floor, either.

Edited by PaulTWinterton

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Sorry Roman, not to hijack your thread, but you raise a good question on different configurations!

Nope, no inlet port on my air intake, just the breather hose!

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and here you can see the line from filler to floor outlet.

image.thumb.png.fd53b0cbbb185c12207173c463a115e5.png

 

 

 

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