[wokenick]

I had a misfire with my 07 335i, so i was replacing the spark plugs and when i pulled out the plug farthest back (cylinder 1 i believe) the plug had more carbon on it than the others and had a slight gas smell, figured ok i have a leaking fuel injector.

I could use some help pointing me towards how to figure out which fuel injectors are needing replaced and what to replace them with

All 6 fuel injectors are index 2 (each one ends with 02, and what i’ve read that indicates the index) from what i’ve read it seems people have a mix of index2,9,and 11 so i’m just kinda lost on what i should replace them with, i’ve already read i should upgrade the index i’m just lost on what index i should upgrade to

i’d appreciate any feedback or advice, if you need any other info to help me out i’ll give it and i’ll include pictures

[Phil325i]

Pretty sure on the 335i they're up to index 12. Best to source them from a BMW dealer and tell them you want the latest iteration. You should not replace just one. You must replace all in the same bank (cylinders 1-3 or 4-6). TBH if yours are index 02, I would say it's time to replace them all...

[Chapperss]

I did the research on replacing single injectors - not a single person I can find who has had an issue replacing just one. That includes mismatching lower indexes with the new 12`s (general advice is not to mix indexes above 10 with the lower ones and replace in banks).

I did this research because I thought I might need to replace an injector but it turned out to be the coil.

[Emilime75]

For years it was believed that you can't mix and match within a bank, and if you had to replace 1 with a newer index, then you had to replace all 3, at the minimum. It's recently, like in the last year or two, been reported that mixing them has no I'll effect. The latter makes sense since the injectors have to be coded to the DME, anyway. Regardless, there's 2 points of view on matters like this. The "it's not broke, don't fix it" crowd, and the "while you're in there, you might as well" types. I'm of the while I'm in there type, so I'd replace them all.

As for what to all to replace with them - start by buying them from a reputable source, not ebay, not amazon, not some random dude on a forum. Reason being is that there are counterfeits out there. Also avoid "refurbished" claims. Buy them new from a place like FCPEuro. Add decoupler rings for how ever many injectors you decide to buy/replace. That's all you need, injectors and decoupler rings. The new injectors will already have new seals on them, and caps that keep them compressed until you're ready to install them - don't remove those caps until the moment you're ready to drop 1 in, i.e. remove 1 old injector, pull the cap from the new injector and install right away. Pay close attention to how the clamping plate is installed, it has a bend to it which is critical. You want the high side of the bend to face up, so when the bolt is tightened down the plate acts as a spring which holds the injector in place and allows some shock absorption every time that cylinder fires.

[Phil325i]

This is the advice I was referring to (feel free to ignore it of course):

Injector advice.pdf

[Emilime75]

...which is dated 2013.

[Steve Sas]

Check and see if you are entitled to injector upgrades from that BMW recall.
I remember they extended it. Worth a try.