Just changed spark plugs and upstream O2 sensors. Observations and a question.
 

I just got this car and while the service history is pretty good, these were original (93k miles) and I don't really believe much in 100K miles BMW recommended replacement. Sure, car was running fine and there are probably cars here with originals over 100k miles but the new components can definitely help.

I got great deal on both. $52 for plugs and $98 for sensors. This is $150 well spent.
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The plugs look to be in decent shape but obviously tired and this one is in the worst shape, probably due to VC gasket leak that was fixed just before I bought the car. It's the one closest to firewall on passenger side and in my experience when the VC gasket fail, oil likes to pool in that spot and slowly works its way around it. The rest of the plugs look much better than this one.
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It's hard to tell the condition of O2 sensors as the lambda is hidden behind the shield but one of the sensors wasn't actualy original which is the proof they don't last forever.
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While changing passengers side o2 sensor, I discovered that wiring loom around the transmission electrical feed has completely disintegrated due to heat and I've rewraped it with 500F silicone tape.
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Now the question: Anybody knows where this line connects. I'm certain I didn't accidentally disconnect it as the car is running fine (actually slightly better). I can compare it to my 540 but it's non vanos and I figure somebody here should know. I'm suspecting that it may not go anywhere but I'd like to know for sure. Thanks.
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Vent tube for the front differential. Just do a search. Seems every NOOB ask the same questions.

It shouldn't be over there, there's a slot on the left valve cover where it should naturally lie in.

I'd do search but I though it might've been disconnected by whoever worked last on the car, therefore I didn't think search would yield anything or how to word the search.

I'd never though to be the breather tube for front diff as I'd expected it to be position much lover. But now it makes sense as the new valve covers were installed just before I bough it and it seems that they didn't put them back.

Thanks guys.

I thought that was a vent tube for transmission?

Ahhhhh...you're right, that's where I tucked mine while doing my valve covers on my 4.6. Just release it and it will naturally fall into the slot at the front end of the valve cover.

Will do. Thanks.

No ,upallnight is right front diff

How are those Lazer plugs working? I heard not to use them ,also the 4 prong , but maybe on a 4.6is.
I stand corrected 4 prong are the OEM and correct plug for the m62 engine.

Yes, the BKR6EQUP are OEM along with Bosch FGR7DQP that I pulled out. People prefer one or other but I never had an issue with these NGK's.

I did about 50 miles today and I believe truck is running slightly better but probably due to fresh plugs vs. tired ones.

I got 14 mpg with mix highway and city but I don't care. The beast rules the road. I'm use to my 540 holding its own on the road but the X5 is quickly becoming my favorite. I can't believe I'm saying this as I always prefer 6 speed and better handling.

Now the air and fuel filter along with PS reservoir hose (the parts are coming tomorrow) and she's up to date on maintenance and repairs.