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beech round cap never opened. this valve cover bought from 50's kid he gets them cleaned in a parts washer first. i have some vacuum in the valve cover so i assume the m56 ccv is working. i have a catch can between valve cover and intake holds about 10 ounces maybe. takes like 50,000 miles to fill it up so i think everything's working fine. so the vacuum line i'm taking about is m52tu engine vacuum on top of fuel rail its a metal thin hose with rubber hoses at both ends. one goes to fuel pressure regulator in 3/2 way valve and other side connects to oil separator. with m56 vc separator is disconnected so i had no vacuum to fuel pressure regulator. I routed that hose to top of intake manifold small hose that runs along top of intake connects at front and back. now i have vacuum at pressure regulator still getting codes p1250, 11188,89, 0170,73. i ordered a replacement pressure regulator. the 3/2 valve i have was used too maybe its bad.
 

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I'm not familiar with those US 2/3 way valve fuel delivery systems. So can't give any input on proper operation of that valve. Thought only US 328i had those while US 323i had fuel pressure regulator located at the end of the fuel rail the same way Euro M52TU engines have. Guess I was wrong.

But doesn't matter whether you have that valve and location of the fuel pressure regulator all E46 6 cylinder engines are supposed to run on contstant fuel pressure.

There should be barely any vacuum at that CCV nipple. If you connected the hose that's supposed to be on the CCV nipple to the intake manifold vacuum you introduced vacuum to a fuel pressure regulator that's not supposed to be vacuum regulated. Connecting it to manifold vacuum probably made your fuel pressure drop.

M54 engines run on constant fuel pressure too. And AFAIK there's also a "vacuum" hose that runs from fuel pressure regulator but instead of CCV nipple it's connected to an F shaped connector in the intake boot next to the brake booster hose. So if you don't have CCV available anymore to connect that FPR hose I guess most proper way might be to connect it the way M54 engines have it.

The hose is broken in this picture but should give an idea of what I'm talking about.

 

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loty excellent info thanks. Ok lets look at it like this. the fuel pressure regulator is supplied with constant vacuum with a small vacuum hose i'd say maybe 1/4" od? about 6 feet long from pressure regulator to the oil separator. Now this is m52tu oil separator under intake manifold that drains oil back to pan and vapors get sucked back to intake. i just looked at separator on ecstuning.com best place to buy parts IMHO. Great place to look up parts for your car even if you dont buy from them very well organized. Sorry side tracking. so i hooked the fuel pressure regulator up to top ccv hose that sits under the vapor return rail if i may call it that i'm sure thats not the right name. When i feel the vacuum on the hose at fuel pressure regulator its not too strong. I know thats subjective if anyone knows what the proper vacuum pressure should be at that regulator at the 3/2 valve i would love to know it thanks.
 

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Normal vacuum on the hose that connects to the CCV nipple is so low you shouldn't feel any suction if you plug it with your thumb. I don't know the exact number as I don't have proper gauge to measure that low vacuum but on some other forums 0.5 inhg was measured IIRC.
 

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thecos:
Has the round plastic cap on top been opened? What is the condition of the diaphragm/spring mechanism and chamber?
I opened it. Broke the original cap. Original diaphragm was intact, good condition except for some gunk on it. However, I replaced it with a new one from e46sulev, along with his 3d printed cap.
 

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2003 330cic, 2003 325iT
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It is fixed, but was in the P030x phase. Didn't leave it broken long enough to get to P0171/4.

But wow did it idle like crap! Fine at speed, and the membrane stayed in place.
 

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2003 330cic, 2003 325iT
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Did a swap on a 2002 325ci (different car) from M54 to M56 to deal with warped cover. Pics on this:

 

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I stumbled upon an idea for finishing off this swap with a custom beauty cover application.

The factory M56 plastic beauty trim looks bulky and frankly undesireable (not mine, don't judge the dirt)


But it also isn't really pretty to look at the exposed coils&wiring etc


On a trip to the PickNPull I noticed a newer model 3 series (e90 I think but now I can't remember) that had a slim cover going down one side and it seemed like it might fit on the side of the M56 cover, so I pulled it



I had to get creative about mounting it because the push-on design would need grommets in the right place, but I ended up having success with a dab of high temp RTV in just the right places (it has stayed put after a number of spirited drives)



I like the look because it shows off the unique M56 setup but also gives a nice 'finished' aesthetic
 

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good job.That looks clean, may i ask where you put the pre cat O2 sensors and how you routed the VCG outlet to the M54 near intake port, it looks like it goes down and under then back up?
 

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It looks like the N52 is the motor that has the thin strip beauty cover that I used to cover the coils.


My o2 sensor wires are in their factory position and the original M54 plastic cover is what is covering them.


I'm happy to elaborate on my vacuum line setup.


If the M56 hose #10 was able to connect to the M54 intake manifold I would have bought it and connected the VC that way, but my understanding is that it has a different sized connection at the intake so it would need to be modified anyway.




So I figured that if I was going to be cutting hoses, I would just do it my way.

I haven't seen an explanation of why the M54 intake manifold has 2 inlets and the M56 only has 1. But instead of capping off the rear inlet, I decided to keep the M54 intake manifold fittings and tee connection in place.

I ran a rubber fuel hose down from the factory fitting, and then it curves up and around the oil filter to meet another line coming off the Valve Cover.





Because of the different sizes of the fittings, the hoses are different also. So I have a step-down fitting that bridges the two lines.





This would have been almost as difficult as replacing the factory CCV valve if I wasn't in the middle of an engine swap, but with my unfettered access I was happy with the results.
 

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2003 330cic, 2003 325iT
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That is exactly what I was about to do! I asked about this tactic in my M54/6 cover swap thread.

Did you consider using the head end from the M56 hose#10 to rubber hose to the M54 y-fitting?
 

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2003 330cic, 2003 325iT
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BTW, I have a ton of split loom if you ever want to repair the corrugated loom at your thermostat. Will send it free if you PM your mailing address.
 

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Cheers, I appreciate your offer but I have already sorted out the sheathing on those wires.

Also I am in Canada so shipping might be more troublesome than the stuff is worth.
 
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