It shouldn't cause a problem but you can try cleaning it off.

iridium or platinum
 

what is your opinion on whether to install iridium or platinum plugs?

I haven't used iridium before, only platinum. I don't imagine there will be a real difference unless you modify the motor heavily. And even in the case of a NA engine, it really isn't going to do anything unless you change cams/timing or something like that. If you had a turbo motor it would be a HUGE concern, but you don't have FI...so don't worry about it.


More ideas:

http://www.google.com/search?q=iridi...ient=firefox-a

How do you gap this?

I do not understand what 'gap' means. I just bought the new spark plugs, the bosch one just as same as shown in realoem.com, and replace the old one and tight them to 30nm. Everything is fine. Is there anything else I missed to do?

Gap or gapping refers to the distance between the center and the ground electrode prong (or prongs in your case) Different motors have different gap specifications which if set improperly can affect combustion and overall performance. When you buy plugs for your specific vehicle they are normally pre-gapped from the factory to the correct specification but this is not always the case. Its usually a good idea to check the gap with a measuring tool (you can pick one up for cheap from any auto parts store). Although with the multi-prong plugs Im not sure how traditional measuring tools would work.

has the OP checked tire pressure? and... driving habits? :p

Thanks for explanation! I bought the bosch plugs and the gap is not adjustable because it is specificaly fixed for e53 x5 engine, I believe.

Strange, I noticed the same thing after replacing the plugs, fuel filter, air filter and oil change.. I was averaging 17.1 with my 4.4 before the work and now it is around 16.4

going to install the iridium plugs
 

i might be going for a trip to the hamptons and i will install the iridium plugs before i go. 'll let you know.