'01 4.4 M62 misfire
 

Frustration, a word we all know I'm starting to learn. Bought the X5 used and here's the story...
Since having her the gear changes would go into "sport" mode 10 to 20 minutes after start. The moment operating temp is reached she would only change gear at 3500 to 4000 rpm instead of normally. Also there is a misfire when you push the accelerator down from idle. Smooth pushing of the pedal gives less "bogging down" and at high rpms the misfire is almost gone. Saw the MAF was unplugged, plugged it in and the problem is worse (struggles to start, misfire, etc.) Got new MAF and put in new spark plugs. Still the same. Had diag done at local dealer, showed VANOS bank 1 & 2 problems, Lean mixture too. Took her to local indy, he opened Vanos and said he found a "bent plate" which he straightened, but errors were still there. Then suggested we replace Vanos solenoid valves, so I did. Got GT1 meanwhile so after changing the valves I diagnosed her myself. Vanos bank 1 error is gone, but 2 still showed, as well as some Map Thermostat error. So I opened the Cylinder covers to have a look. Couldn't find anything seemingly wrong on bank 1, bank 2's pulse wheel generator had 1 bent piece. So I straightened that. There was also a LOT of oil in the spark plug recesses, so drained that and replaced the gasket seals under the cylinder covers. Also replaced the OSV and found the oil return pipe was hanging loose on the old OSV. So I maneuvered it onto the oil return that goes to the bottom sump. Put everything back together and started her up. Still the same. I haven't done a diag again but had another look at the vacuum pipes (it seems to be a common thing on the forums) and saw that the oil return pipe from underneath the intake manifold to the OSV was missing. So I took off the intake manifold and this is where I am now....(maybe worth mentioning, when I released the fuel line going to the fuel rail some fuel trickled out and it seemed not to be under pressure at all, I'm thinking it should be under pressure right?)...(see attached pics for oil in sparkplugs, intake manifold etc.) Any ideas guys? By the way at no stage did I get SES, CEL or TRANS lights or warnings.

WOW! thats one neglected x before you owned her. maybe a faulty fuel pump if the pressure isnt there or a clogged fuel filter. your also missing the valley pan cover. since you have all that off you might as well change the water pump and valley pangasket as they fail around 70-100k(preventative maintenance). since that reeturn hose was not installed that is probably where a lot of the oil came from and when the valve cover gaskets blew. where did you buy the X5? freezing temps will often lead to frozen oil seperator, I would change yours to the newer insulated one. good luck with everything. clean those intake ports too, that a lot of oil residue that shouldnt be there.

Tell me about it! I did get her at a bargain price on auction BUT had I known about all the issues I wouldn't have taken her. Yet here we are and I need to sort her out.
Thanks for the advice, I'm going to get a new fuel filter tomorrow, its on my list.
1. Whats the best way tot clean the intake areas?
2. Could the missing oil return be the culprit for the misfires etc.?
3. I'm in sunny South Africa, so I guess they don't bother with the insulated OSV.

Its probably worth mentioning as well that the oil filler cap gets sucked so tight I have to use 2 hands to twist it open...

the suction on the oil filler cap will be due to the diaphragm part of the oil separator , the part at rear on centre of intake manifold .
I agree with jst2878 on changing the valley pan and water pump .
not sure about fuel pressure but it does have a relief valve , so maybe no pressure after switching off , just a guess .
looks like the diaphragm has been burst for a while because of the crud in the intakes . this is because oil gets sucked through the burst diaphragm .

What exactly does the valley pan do and how does it work? When I removed the intake the valley pan had no cover (like the attached photo).
And while were at it, could the missing oil return pipe be the reason for the vacuum in the engine?

that missing hose comes from the oil seperator which in the last photo is that black thing in the far left of the pic. that could be causing a vacuum leak or maybe one of the black with yellow or black with blue hoses is cracked somewhere. thats the hoses that sit right above the intake manifold. check all of this and try and locate that missing hose off the seperator. that oil probably came when the gaskets blew so hopefully once you clean it all up your x will run good.

If the missing hose is the for the oil separator then it would strongly suggest the that's causing the misfire. My 2001 X5 4.4 had tears in the oil separator hoses which resulted in three engine misfire codes. After replacement the misfires stopped. Given the condition of that engine I wouldn't be surprised to learn there are other issues. But not having an oil separator hose is definitely an issue.

Thanks guys. Hopefully I'm in the right direction (I've got a new OSV, you could probably tell from the photo) and I ordered new hoses from BMW so will have those tomorrow. As well as new gaskets for the intake manifold (the 8 inlets at the bottom, the two on the sides between the covers and the one between the cover and the throttle body) and a valley pan cover. I had the injectors tested yesterday and all are fine which is a relief. Got some new o-rings for them anyway. Are the yellow and blue hoses different in size/type or just colour coded not to put them on wrong? And what on earth is the valley pan for?

Might as well do the water pump if it has over 60k, u also need water pump gasket and the four orings for the two coolant pipes that go into the waterpump. To do the valleypan u have to take the waterpump off. Clean and lubricate your pulleys since you have to take the belts off.

Well I replaced the missing hose to the oil seperator and replaced the intake gaskets as well as the gaskets at the back cover and front of the intake manifold. Cleaned everything up nicely while I was there. I checked the valley pan and there were no leaks so didn't deem it necessary to replace.
So put it all together and started her up. Still the same misfire though. I took a long drive (133km) and found that whenever I push semi hard on the gas she bucks and momentarily loses power. Today I did an oil change (plus filter) and with the engine idling the MIL came on. I then did a diagnostic (GT1). It came up with a mixture adaptation on bank1 and bank2 that was incorrect and adaptation, map cooling as well. (plus a few other faults but I'm aware of the steering angle sensor thats faulty etc.) So I cleared the fault memory and started her up again. No lights, all good.(smooth running test confirmed all cylinders idling fine). So switched off and disconnected GT1. But when I switched her on again she idled VERY rough at about 1200rpm and engine failsafe prog displayed. I could depress the accelerator as far as I like but nothing, no change. So reconnected GT1 and checked again, it had same codes plus a learning module, lower somethign faulty. I reset again and started, all fine. Switched off, started again, engine failsafe prog plus rough idle and no response from accelerator. Reconnected GT1, cleared again, started up with no problem. Disconnected GT1, went for a drive (didn't switch off the engine) and she drove nicely. Got back, switched off, switched on again, failsafe prog plus rough idle and no throttle response. I'm stumped...
I did note that when I usually put the ignition in pos 2 there is a high-pitched whine from the front left of the engine. Each time I got the failsafe prog and put the ignition in pos 2 the whine was gone until I cleared the fault, upon which the whine would start right up and I would be able to start the engine with no problem. Any ideas gents?