Ah ok, noted and good to know. I will update with consumption numbers after the ccv replacement.
I'd like to add my car to the list of (probably fixed) oil burning cars. 2005 530i 6spd, driven to the rev limiter and off throttle at high revs every day. It's burnt a quart every 500 miles or so, but I could never see smoke, but to the point that my bank2 cat converter got stopped up (!!!). I just did this mod, and after reading through a lot of this thread to understand why this works, the only logical explanation I can come up with is that the extra vacuum just keeps the diaphragm shut tightly and essentially disables the ccv from working. Considering the amount of vacuum when I try to open my oil canister, there's no way that wimpy little spring can push against the diaphragm. The small vacuum tube to the intake is so small that not much air volume can pass, and its just enough to burn crank case vapors without sucking oil. It's a great mod, and nice of BMW to include a vacuum port exactly where it happened to fix this issue.
No I don't think so. The extra vacuum in the CCV (intake pulls more gas via the additional hose) creates more vacuum in the crankcase, which helps to seal the pistons rings better, and so less blow-by gas into the crankcase, this means less gas and oil vapor cycled through the CCV. The only down side to this mod is a 5" HG or 65" water (10x of the spec) vacuum might crankshaft seals to leak air in, or the tremendous force pushing down on the plastic valve cover at 2.5psi (multiply 2.5 to the total VC surface area, i.e. 160 sq-in x 2.5psi = 400 pounds on the VC).
Yes, the high vacuum shut close the CCV diaphragm but the gas still being sucked into the engine via the hose from CCV to intake. Sure the gas must be flowing from CCV into the intake in order to create this vacuum, regardless the CCV diaphragm closed or opened.
Last edited by Sapote; 08-24-2022 at 02:58 AM.
It is possible that the increased vacuum in the crankcase caused more air leak through these parts: valve cover/gasket; crank oil seals; dipstick tube o-ring, just to name a few. Extra air will cause lean mixture and positive fuel trim. Obviously it depends on the condition of these parts.
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