Help with OBD II codes, diaognostics ??

[HikinTech]

I just had a vehicle today that has mixture too lean faults. I smoked the intake and could not find any leaks. I believe that there is an internal leak inside the oil/vapor seperator. I have not performed the repairs yet (awaiting customer approval). Same engine as yours. This may be where your problem lies. Except your original faults you had a fault for the tank vent valve. If the leak is internal that there are really only two possible causes. The TVV or the oil/vapor seperator. If you do the oil/vapor seperator, I recommend that you get all 4 hoses for it also. At the very least the bottom hose going to the drain tube. You normally end up breaking the hoses when removing because they become brittle. I hope this helps.

[malibumlk]

Hikin,
YES! it sure does help.

I'll be vary interested to know if your Oil Separator leaks internally with no obvious external leakage or oil seepage. I appreciate to comment on the hoses too. I've fondeled every hose in there, none are brittle at all.....but it may still be worthwhile just to make a tough job easier.....and especially the line from the dip stick.

If you do see an internal leak inthe Oil Sepatrator, let me know if there would have been a trouble isolaton I could try (like block one hose for instance) because it's a b__ch to get that bugger out of there.

Please let me know what you ultimately find.

My plan at this point is to:
a) check the TVV based on the odd code (clue??) and because its so easy to check.
b) then smoke it
c) if nothing, and depending upon what you find.....do the Oil Separator. Either this or keep driving for a while and hope for a new code/clue.

Thanks again.
Mike

[HikinTech]

Customer did not buy the repair, so I will not know if it fixed it. Probably will get work done by cheaper place.

[malibumlk]

Hikin,
Thanks for the follow through.....much appreciated.

I checked the TVV this weekend....and as you suspected......it was closed tight as tight could be. Odd thing though, I had a re-occurance of code 276d....."tank Vent Valve".

I suppose it is possible that the TVV fails to open on occasion, thus triggering the code, unrelated to the lean mixture codes. I'll deal with that separately if that's the case.

All of the Laen/mixture Prep. codes were present as usual along with the TVV code.

Question: while continuing to search for an external vacc. leak, I had the engine at idle and pulled the dip stick......full vacuum in the crank case. Is this normal, or possible confirmation of internal leakage of the Oil Separator valve?

Next question (and after the Q? above): In review of the Vacc/ intake system, I don't see a possible external air flow path from an internal failure of the Oil Separtaor Valve.....where does the vacc. air flow originate if the system is sealed and the crankcase is at full vacc. pressure (negatve pressure) ??

Is any of this pointing to the conclusion you came too on your recent customer car.....i.e. internal leak of the Oil sep. Valve????


Thanks Hikin.........big disapointment on your customer car that we couldn't see it through.

Mike

[HikinTech]

Answer to first question. That's hard to say for sure. How we normally check the oil/vapor seperator is with a tool called a manometer. My shop is new and that is an old tool so we do not have one. We hook up the tool to the oil fill port and run the engine.
2nd question. There is a hose that runs across for intake manifold that eventually hooks to the intake manifold. So you would have unmeter air that way. I normally don't see internal leaks but it does happen.

Do you know if the TVV fault is stuch open or close. If stuck open replace the TVV, this may be your problem.

Sorry, I don't have too much more information for you. I hope you figure it out.

[malibumlk]

Answer to first question. That's hard to say for sure. How we normally check the oil/vapor seperator is with a tool called a manometer. My shop is new and that is an old tool so we do not have one. We hook up the tool to the oil fill port and run the engine.
2nd question. There is a hose that runs across for intake manifold that eventually hooks to the intake manifold. So you would have unmeter air that way. I normally don't see internal leaks but it does happen.

Do you know if the TVV fault is stuch open or close. If stuck open replace the TVV, this may be your problem.

Sorry, I don't have too much more information for you. I hope you figure it out.

Thanks Hikin, I realize we're about as far as we can go here;

As for Q1 on the Oil Separator: The use of a manometer implies a comparative vaccum measurement at a very low level measured in "inches of water" typically (full vaccum being 28 inches of H2O if I recall. One end to the oil fill, the other end to another location......where? Because if it's to atmosphere, mine will suck full intaker manifold vaccum based on my estimation comparing at various points in the intake.

As for the TVV: the code doesn't speak to open or closed, but the vale is closed tight out of the car, and in the car with the engine at idle or turned off. So I'm assuming that it is "normally closed" requiring a signal voltage to open. If this signal is intermittantly applied by the ECU under some set of conditions and the valve failed to open.....then it triggers a code. But that's a different issue. I'll pull it again and apply 12V to see if it operates and closes.....and I guess I could just replace it.......but it doesn't look like the issue.

Back to the Oil/Vapor: can you refer me to, or post the manometer test and the desired vaccum differential so I can check mine t6hat way? I've not seen this test in the BMW manual.....I'm suspicious of that item but trying to avoid the cost/effort of swapping that part and hoses unless it is confirmed.

Thanks again.

PS: pls PM me you business and contact info. My sister lives in Sacramento and has a whole fleet of BMW/Porsche that deserves good indy care.

Mike

[malibumlk]

HikinTech got me there with his suggestion that crankcase vacuum ressure should be in the range of a few inches of H2O vacuum; if not the air oil separator was shot/leaking internally.

I found that I had full intake vacuum in the crankcase......you had to pull pretty hard on the oil fill cap with the engine running to get the cap off.....and once off, it was a giant sucking like a vacuum cleaner ....until the crank case pressure equalized. Certainly not a few inches of H2O. I compared it using the palm of my hand as a vacuum gage/manometer.....to the X5 we also have and it was day and night.

Once removed and broken open, the old valve had a tear in the diaphram (to the atmospheric vent port) about 1/3 of the way around.

It's now apparent that the rough idle on start up was due to extreme lean condition as the entire crankcase was drawn to intake vacuum pressue level....once there, after about 1-2 seconds, the mixture returned to/near normal, and the idle smoothed out.

Thanks agian for your all of your great help and all the clues.

BTW: there's a great DYI on replacing the air/oil separator in Bimmerfest.

Mike