[Art_Vandelay]

I just changed the sparkplugs on my '09 335xi, which has 35,000 miles, and am hoping for some input on the condition of the old plugs and one of the coils that looked a little suspect. I've included a couple of pictures of the old plugs, and of one of the coils.

Although I'm not very experienced at reading plugs, the firing end of the plugs looked about like I expected, and don't notice anything concerning there (although I welcome any opinions on that). But there are two things that looked a little out of the ordinary. First, as can be seen in the photo, the ignition coil for cylinder 3 (the third from the front of the engine) has a white deposit on the end (no jokes . Additionally, the plug for that cylinder also has similar deposits on the bolt portion.

Is there anything to read in to this? All the other coils looked pristine, and none of the other plugs have similar deposits.

For a little context, I'm not receiving any primary codes, either before or after changing the plugs -- I have an INPA cable being delivered this week, so I'll be able to check for shadow codes soon. However, my gas mileage is quite poor, at around 12-14mpg city even with very conservative driving. Highway mileage is around 25, so ok there. I've only had the car for a couple of months, so I can't really say whether that is worse that usual for this particular specimen. Power seems pretty good when I get on it, but does seem like maybe a little is missing at half to three-quarters throttle, relative to other 335's I've driven. So, nothing seems dramatically off, but just a few things that seem slightly off.

[Art_Vandelay]

Bump... Any input would be appreciated.

[Phil325i]

TBH I don't think you've got anything to worry about. All looks very normal. The White deposit was probably a bit of condensation/dampness that dried. Wipe the coil clean and enjoy!

[Art_Vandelay]

Thanks, Phil325i, I appreciate the input

[Meeni]

Your plugs look normal. 25mpg hwy is poor (well hwy like interstate or like twisties with the hammer down?). 14 mpg city is normal.

The white substance is probably dried up electrical grease. Wipe and regrease. Done.

[Ghiurau27]

yeah your highway mpg sucks. I get 29 highway with aggressive driving.

[SLOWER]

I bought my 335 with 32k miles on it. The best MPG I've ever gotten was the run home from NY to MA where it was like 20.5. It stays somewhere between 18-20 now. Thats about 75% hwy driving.