Neeed help 2/2006 4.4L misfire, out of time

[SoonerBred1963]

OK, I really, really need help.

2005 BMW X5 4.4L engine.

I purchased it at 146K miles, now has about 163K miles. (Super clean inside, seemed well taken care of).

Prior history that I know was that prior owner hydroplaned and hit yellow barrels. I got super lucky and found and replaced for both doors and front fender (driver;s side) from salvage yard.

Drove it without any real problems for about 11 months. The only thing I ever noticed is that often when I would start it up, after about 2-3 minutes, the rpm would nose dive and it would die or almost die. Other than that, no knocks, or rough idling, or anything.

Week before thanksgiving, I pulled into the car wash, and I was leaking oil badly. I immediately checked the oil topped it off, drove it home and parked it. No stop engine low oil pressure light came on.

First guy replaces (1) Oil pan gasket, (2) alternator bracket gasket, (3) oil filter cap, (4) water pump, (5) thermostat (there was a small leak out of the weep hole, and the thermostat had thrown codes).

After waiting on the parts, it all got installed.

On the drive home, it ran OK at first, but then it started running rough. At some point, the stop engine low oil pressure light came on and I immediately pulled over. I checked the oil, but everything was sealed up, turned it back on, and no warnings came on. Subsequently, the low oil pressure light did not come on again, but it ran rough.

I checked the VANOS solenoids on the Bank 2, they were clean, cleaned them with MAF cleaner put them back in. No change.

Guy number 2 comes to work on it at the house. Very meticulous, checking everything. Bank 2 has all the misfires. He finds that the eccentric shaft sensor on bank 2 is broken. Wait on that part, then he also changes the valve cover gaskets. He also tests a lot of the parts they seem OK.

We fire it up this morning, still misfiring.

He checks the coills, and the one all the way at the back on Bank 2 (8?) shocks the heck out of him. He has an extra coil, he swaps it out, it no longer shocks him. But it still knocks, and backfires on what appears to be Bank 1.

This is kind of expensive to throw parts at, and actually parts are hard to come by.

But the present plan is to change out the coils on Bank 1, that is where the backfires are happening. I have suggested if this does not fix it, should our next step just be the cam sensor and/or crankshaft sensor?

I am really, really stuck. Been without this car for about 3 weeks now. If this helps, when he had the valve cover off, he looked at everything, and everything looked good up top. He had no indications that it had ever run dry, or was damaged in any way.

If you have any suggestions (burial is not a suggestion) please let me know. This is very frustrating and disheartening especially when you hang in there after a week or so, and crank it up and it is no better than when you started.

Thanks.

RTW