[mjleamy]

I just changed my plugs after 99,810 miles. The DIY is great for getting this done, and it isn't even difficult. As much as BMW gets kicked around on these forums, I have to admit I am impressed with how these look after 100k (see pictures below). All 6 came out of the head looking about the same with no signs of burning oil or a poor mixture. I did crack the insulator on the first one, which is a lesson learned. They do not want to come out of the head after 100k without a little fight, and I should have been more careful on that first one. The cracked insulator left a bunch of ceramic particles in the spark plug hole, which I promptly sucked up with a vacuum cleaner. Since I had it out, I vacuumed every hole afterwards. It isn't a bad practice when you think about it as crap falls down there over time. Besides preventing debris in the cylinder, vacuuming gives a nice, clean surface for the plug to mate and seal with.

When you look at the old plugs, you can see the electrodes are badly worn. I checked the gap on one of them and it was 0.035 inches. When new these NGK plugs were 0.044 inches according to the DIY. The new Bosch plugs were pre-gapped to 0.04 inches (yes, this is supposed to be different from the original NGK). I checked each one and they were dead on.

So you probably are wondering if my 330xi is running any better after the plug change? To be honest, it ran flawlessly before the change, so I can't say there is much difference. Maybe it feels a little stronger and a tiny bit smoother, but it ran so smooth to begin with it is really impossible to tell.

Pictures (sorry, they are not the best):

All six, in order, with the cracked one coming from the front of the engine


first close-up


second close-up

[GoRomeo]

Thanks for sharing your experience about your plugs. I did this job about 2 yrs ago. Mine looked the same as yours. Are you replacing the coils too? I haven't but I am tempted to do it soon. I am at 117k miles.

[PichaDis11]

Thanks for sharing as well. I am about to do this around this weekend to get rid of a misfire I've been getting every now and then.

Could you share on exactly what happened why the plug cracked?

[chazzz]

BMW Maintenance schedule shows that you need to change the plugs every 100k. I have to disagree with that. It's better to change the plugs every 40k to 50k. That'll keep your engine happy. Spark plugs aren't that expensive if you do-it-yourself.

I usually change the plugs in my Jeep every 25k or so, they're so cheap (Champion copper plugs, about $10 for a set of six plugs).

Platinum tipped spark plugs (in BMW) aren't designed to go for 100k.

[Rg21044]

If you don't mind me asking, how much were the replacement plugs. Thanks.

[BMRSEB]

Mine looked about the same.. I changed mine at about 95K, not sure when they were changed so wanted to at least have a record of my own. Good thing is no oil residue, VCG in good shape.

[Blackhawk36]

They look like the center electrode is slightly shortened from erosion but not bad at all. The top one looks like there it is running rich (it has a black powdery coating appearance) or the combustion isn't complete. New plugs might fix that.

[mjleamy]

Originally Posted by PichaDis11

Could you share on exactly what happened why the plug cracked?

I think it cracked because when I was torquing on it, I got sloppy and didn't keep the wrench centered on the plug. So I basically put bending stress on the insulator. Brittle materials like ceramics do not like to be put in tension

As for Blackhawk36's response about the one plug being a little more black, I agree that that plug shows the cylinder is running a little rich. I guess that could be a number of things, to include an injector not metering fuel quite right.

Rg21044 --- I just looked back on my Amazon order. I bought them directly from Amazon (not one of their other merchants) and the total for 6 was $55.80. I have Prime, so shipping was free. For comparison, Pelican has them for $11.75 per plug. Amazon is a lot better.

Last comment - IMHO, I wouldn't change these before 100k miles on an N52. There is no need as evidenced by looking at my old plugs and those from others. Exposing the cylinder to the outside world, yanking on the coils (and you do have to yank and crank on those suckers a little bit), and stressing underhood wiring and such more than necessary just isn't worth it. Besides, it takes some time to do that I would rather spend otherwise

[ctuna]

Do you notice any difference in running?
Smoother or better response?
Where they pre gapped?

Mike Miller mentions that taking them out early is as much about
getting them out before they seize and looking for oil leaks around the
plugs is it is about replacing bad plugs early.

[Saintor]

Last comment - IMHO, I wouldn't change these before 100k miles on an N52

My Bosch barely passed 65K and I had 2x misfires issues, then changed all of them. So yes, I would say change them at 60K miles (at last if they are Bosch ). I replaced my Bosch with NGK. I don't trust Bosch.

[mjleamy]

Originally Posted by ctuna

Do you notice any difference in running?
Smoother or better response?
Where they pre gapped?

Mike Miller mentions that taking them out early is as much about
getting them out before they seize and looking for oil leaks around the
plugs is it is about replacing bad plugs early.

Really cannot tell the difference in running, but it ran fine before the change. Yes, they were pregapped, but I checked each one. As I wrote above, they were dead on.

[pspressart]

Originally Posted by chazzz

BMW Maintenance schedule shows that you need to change the plugs every 100k. I have to disagree with that. It's better to change the plugs every 40k to 50k. That'll keep your engine happy. Spark plugs aren't that expensive if you do-it-yourself.

I usually change the plugs in my Jeep every 25k or so, they're so cheap (Champion copper plugs, about $10 for a set of six plugs).

Platinum tipped spark plugs (in BMW) aren't designed to go for 100k.

When my car was at the dealer for the VANOS recall work, they also changed the spark plugs because I supposedly requested it (My SA really takes care of me). This was with 55k on the odometer. I have noticed a difference in the performance after the change.

[mjleamy]

Originally Posted by pspressart

When my car was at the dealer for the VANOS recall work, they also changed the spark plugs because I supposedly requested it (My SA really takes care of me). This was with 55k on the odometer. I have noticed a difference in the performance after the change.

Note that 335i has an interval change of 45k from what I have read.

[FL335]

20-25k intervals w/ any tune on an n54. I could;t imagine not doing this basic stuff at reasonable intervals. OP, your car must hate you.

[Antetokounmpo]

Originally Posted by FL335

20-25k intervals w/ any tune on an n54. I could;t imagine not doing this basic stuff at reasonable intervals. OP, your car must hate you.

The 325/328/330 recommends every 100k. NA engines spark plugs last way longer than turbo, especially with a tune.

On a side note to everyone, I'm assuming oil reside and smell from spark plugs mean the VCG needs to be replaced?

[FL335]

Originally Posted by bk335

The 325/328/330 recommends every 100k. NA engines spark plugs last way longer than turbo, especially with a tune.

On a side note to everyone, I'm assuming oil reside and smell from spark plugs mean the VCG needs to be replaced?

Yeah BMW also recommends 15k for oil changes on he n54….GL w/ that. I had always found if you do the basics, cars last. Some of BMW's service intervals are "off"….

[Antetokounmpo]

Originally Posted by FL335

Yeah BMW also recommends 15k for oil changes on he n54….GL w/ that. I had always found if you do the basics, cars last. Some of BMW's service intervals are "off"….

For a stock N54, I would do what they recommend if I was under warranty since maintenance is free. BMW isn't going to tell customers to do it not frequent enough, they don't want their engines going bad too soon. Personally, I do mine every 5k or so but that's overkill, todays synthetic oils are so much better, some even recommend to change it as little as every 20k miles.