After doing an 02 Pilot Mod on my BMW E46, the check engine light comes on saying that the engine is running too lean. It does seem to run better, and I haven't been able to drive it long enough to see if oil burning has stopped. Does anyone have any thoughts?
P.S. I'm highly aware BMW's are money pits, I just can't get rid of mine yet.
Although it may seem to be running better, I highly suggest fixing the lean issue before driving it. It is very dangerous to operate your engine when it is running lean (higher chance of preignition). Perhaps that mod you did (please explain to me what that is...I've never heard of it before) caused some sort of a vacuum leak somewhere to cause the lean code. Do you have access to a scan tool to take a look at your fuel trims as well as your O2 sensor voltages?
Here's the link for the mod:
And my scan tool isn't smart enough to check fuel trim unfortunately.
@n_estevez
So I watched the video, it was pretty interesting. So which setup did you use, the check valve setup at the beginning or the vacuum line setup at the end? I anticipated that there would be some messing around with vacuum lines for this mod. Lean codes are usually caused by loose vacuum lines or hoses that allow air into the intake PAST the MAF sensor (unmeasured air). Perhaps check the CCV connection and hose itself that connects the valve cover breather to the intake manifold. And check all those vacuum lines you added for this mod as well. It seems like the publisher of the video did not have any lean problems with that setup. Let me know what happens!
I did the vacuum line setup. I also replaced the CCV a year ago when I got the car. I can check vacuum lines again, but I think with this much headache, I'll just put it back how it was. Thanks for looking into it!
Put it back to the original and see if the code goes away. If not, then the issue is somewhere else probably and needs further investigating. Honestly, those engines naturally consume a whole bunch of oil due to how it was designed, but BMW hadn't addressed those issues until they corrected it with their newer B engines. The N engines, especially the N54/55 were well-known for oil consumption and resulting carbon build-up. Their oil separators were not designed very well. Good luck!
"Their oil separators were not designed very well" that's an understatement! The whole pcv system... well, it might be ok if they didn't use plastic to make all of it! I replaced mine with a system I designed myself.