Vacum hose going to brake booster

[t_marat]

I have one nipple sucking in air, as shown in the picture. At first I blocked it off, idle become a little more smoother. I did it so because I saw Wingman's post before where there was a nipple like that and that was blocked. But the idle became completely unstable once the engine is fully warmed up (temperature gauge in the middle). It just stalls. Openned again that nipple, and it does not stall anymore.

Link to that post:
http://www.bimmer.info/forum/showthr...ghlight=vacuum

In those posts it was stated it is used to draw air over the temperature sensor. The same for me? Mine looks a little different.

[wingman]

mmmm interesting. The first time I got my car up to full operating temp after closing the hole up I got a couple of big misses when doing about 110kph (65mph). Since then the problem has gone and I'm happy with the performance. The idle is still smoother and no adverse effects. You may have another issue.

[genphreak]

I have one nipple sucking in air, as shown in the picture. At first I blocked it off, idle become a little more smoother. I did it so because I saw Wingman's post before where there was a nipple like that and that was blocked. But the idle became completely unstable once the engine is fully warmed up (temperature gauge in the middle). It just stalls. Openned again that nipple, and it does not stall anymore.

Link to that post:
http://www.bimmer.info/forum/showthr...ghlight=vacuum

In those posts it was stated it is used to draw air over the temperature sensor. The same for me? Mine looks a little different.

Definately it should be blocked off, unless it was used for running the cabin's ventilation flaps (you'd know the ventilation/demister etc would not be working properly). In which case find/repalce this pipe and reconnect.

Otherwise you should block it off and try a Shogun's reset procedure. (search is your friend) whereby the car's engine computer (ECU) is reset. Basically you disconnect power to the ECU for a short period and it forgets its learnt data, returning to factory defaults. ON reconnection and some driving it learns your engine anew.

If this doesn't work and it still stalls, someone has probably adjusted the Idle air bleed screw on the Air Flow Meter right up (thus making up for the air drawn in from that damn little pipe after the original bung came off). Or maybe your motor has other settings... maybe idle? Check the Bently for details on how-to do all this... Don't fret about it if so, if it is the case it shows your motor is has no OTHER vacuum losses (ie intake leaks). This is a good thing as many have had to battle hard to find leaks...tho more suspect them for other reasons...
Nick

[t_marat]

What that white thing is? Here is a diagram:
http://www.realoem.com/bmw/showparts...24&hg=11&fg=40
The only thing I can see is the temp sensor. But as visible in the diagram, it is at the middle of the throttle body. But that white thing is located a little higher than the throttle body.

[genphreak]

What that white thing is? Here is a diagram:
http://www.realoem.com/bmw/showparts...24&hg=11&fg=40
The only thing I can see is the temp sensor. But as visible in the diagram, it is at the middle of the throttle body. But that white thing is located a little higher than the throttle body.

Non return valve. Stops your engine copping the changes in pressure from the brake booster when you brake or if it fails. I replaced mine when I broke the pipe off, it cost a heck of a lot at the stealer over AU$50, man was I ripped. Every now and then they find a way to get me, it's just life.

[t_marat]

Sorry, but what does "copping" mean?

[joshua43214]

Sorry, but what does "copping" mean?

Copeing with means to deal with.

Also the description is a bit misleading. It is a check valve that maintains high vacuum in the power booster. You will notice the little arrow embosed on it, this points in the direction of air flow, which is from the booster to the engine. This valve allows you to have full power brakes in the event that the engine stalls or in low vacuum situations. If the power booster fails, the engine will draw air from it and you will have a large vacuum leak.

[t_marat]

If the power booster fails, the engine will draw air from it and you will have a large vacuum leak.

That is if the power booster fails or if the check valve (non-return) fails?

[joshua43214]

That is if the power booster fails or if the check valve (non-return) fails?

If the booster fails, you will have a large vaccum leak that will pull right through the check valve, since it seals vavuum into the booster.

If the valve fails, the booster will not hold vaccum and you will not have power brakes in low vaccum situations.

the valve also has a built in restriction that "smooth's" out the demand from the booster. If you removed the valve from the circuit and punched the brake pedal the engine speed would dip suddenly and possibly stall, from the sudden change in manifold pressure. The restriction is matched to the aplication, so you must use the proper replacement part rather than any kind of universal booster check valve.

[genphreak]

If the booster fails, you will have a large vaccum leak that will pull right through the check valve, since it seals vavuum into the booster.

If the valve fails, the booster will not hold vaccum and you will not have power brakes in low vaccum situations.

the valve also has a built in restriction that "smooth's" out the demand from the booster. If you removed the valve from the circuit and punched the brake pedal the engine speed would dip suddenly and possibly stall, from the sudden change in manifold pressure. The restriction is matched to the aplication, so you must use the proper replacement part rather than any kind of universal booster check valve.

Thanks Joshua for the details there, I was indeed more sepculating it did something interesting... your description is very informative. Now I feel better about spending $50 on it since it is so important... Nick

btw; by 'copping' I meant incurring, but we're all on the right track! My apologies also for using this Aussie slang word.