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What is that vacuum device?
Posted: Sun Dec 28, 2025 12:45 am
by tlake
What exactly is that item attached to the left side of the intake manifold in the pic below. Is it vacuum related to keep the revs up when the a/c is on
530iEnginePic
Re: What is that vacuum device?
Posted: Sun Jan 11, 2026 11:04 pm
by 528i-1981
I think it's the vacuum limiter for the EGR. From what I've read, this prevented the EGR valve from opening too aggressively an cause excessive exhaust recirculation disrupting the mixture and affecting performance, especially at idle. This is just based on research, my 81 528i does not have this device.
Re: What is that vacuum device?
Posted: Mon Jan 12, 2026 1:42 pm
by Mike W.
That's the gulp valve. It prevents backfiring on deacceleration. I suspect 530's didn't have coasting fuel cut off which 528i's did. 528i's cut fuel off above ~1300 RPM with the throttle closed.
Re: What is that vacuum device?
Posted: Thu Jan 15, 2026 10:00 pm
by tlake
Thanks 528i-1981 and Mike W. I think it might be on all L-jet Euro cars too pre 1981, that didn't have the fuel cut off system. Might have to look at some Euro/US articles on the early 528i.
Yeah, from article pics it seems the 1979 US / Euro cars have the gulp valve too.
