one bad park plug.....
 

I guess I have a bad cylander .its the first on the passger side......it's just black and caky compared to the others........I have a picture on the FB page ....any thoughts?

I had a bad plug. That was the cause of the gunky cylinder. Change it and take a look after 100miles.

The plugs were single electrode I went back to OEM NGK four electrode.


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Thanks , I changed mine at least 3 times and it seems that that front passenger side plug always has shoot on it ......the 4.8is is standard with the single electrode.....NGK lazer iridimi ...

A compression test would help a lot in the diagnosis.

Good to hear you've already changed plugs, are sticking to the specified plugs, and the problem still comes back. That rules out a lot of the easy fixes.

All six of wife's single electrode looked covered in grease after 30,000 miles even less (and causing misfires bad enough for faiksafe). My 4-electrode were dusty and dry after 50-70,000 changed as preventative measures I'm sticking with 4-electrode. We do have the 3.0 so the 8s may do better with the singles.

"What he said" wrt the compression test. If one cylinder acting different. Compression test is the go-to move. Also swap a plug and coil pack from a different cylinder to see if the problem relocates.

Black and dry is a sure sign of poor combustion. Wet and dark is an oil control related issue. Since I assume you do not have access to a lab scope, I would recommend replacing the coil on that cyl or at the least swap it for another location to see if the "issue" moves with the coil.
Issues Questions - Cyl misfires under load? Hard starting on hot soak? Idle stable or "hunting"?
Ignition Issues - Coil or plug (Or both) Don't forget about connection failures
Fuel delivery - Injector leaking, stays open (drips or incomplete spray pattern), clean system with injector cleaner. Better? Y/N, No move to injector removal and ultrasonic cleaning and new seals.

Quick tests
With a digital volt meter read the resistance of each plug (one higher than the others?)
Connect a scanner to the OBDll port, display live readings. Before starting check the stored codes and see if there is any indication of engine cyl issues.
Disconnect the problem cyl coil for 15 secs and record RPM drop, then do the others on the same bank. 10% greater difference from any location? Note O2 Sensor readings during tests. Any wide variations between cyls when coil is killed?
You can alway do the same test with each injector.
Clear codes when complete as the module will record cyl misfires.

The single file wire plugs will provide a better ignition burn than any given multiple prong plug in our applications 6/8. Those reporting otherwise have ign issues, fuel issues, or oil control problems, all of which can be typical symptoms of aging systems. Time to clean combustion chambers, injectors, replace coils, etc. Lab scope, 4 gas meter, and proper diagnostics will prove out everytime.

Helpful?

Thanks a lot , I replaced the coils last year .....with delta from BMW........the engine is running good, It's the cylinder right next to oil fill cap , it might be from oil spills.......the plug is dry and caky....black.

No error codes?

No none , I had a code with oil cap loses , 1353. no codes ,with the new spark plug and I ran the x5 for 500 miles and pulled the spark plug today, it looked sutty and black .. I cleaned it up and check the connection for the coil and the plug into the coil......feels a little better... I will check pluga agin soon.

congrats! Hopefully it is/was a loose connections. Real weird it did not pop a code as a misfire.