[Jet-Black]

Hi everybody, Grandpa driver here seeking your help. I’m seeking to locate a decent source for INDEX 9 (N54) injectors and also some advice for additional maintenance if you are kind enough to share with me.

I own a 2008 335xi, it has 182000 miles and no mods other than the dual Air Cone filters. I got the vehicle last year and it has been awesome. I neither abuse it nor intend to take it to a track or anything like that. I bought it because I have always liked the model, engineering, and having such a good torque at 1500 is just glorious. I shift in the range of 2800 – 3200 and the most I get the RPMs up-to is 4300k when needed to boost up a little to overtake a semi or something like that. I have replaced all oils/ spark plugs as new ownership maintenance (preventative) to have a decent/traceable starting point. Everything is great with this vehicle but it has developed Injector Leak on injector 5 which turns out to be an INDEX 6 injector (all other are INDEX 9).

I bought a “refurbished” injector INDEX 9 from Amazon but it turn out to be a dud. – Do you have any good sources to get a pair or so. I will really appreciate your advice.

Thank you,

[Wolf 335]

Unfortunately index 9 are just as bad.

If budget allows start with one bank and pop in 3 new index 12.

[Jet-Black]

Wolf335
Thank you for your reply. Is that possible? I thought upgrading to Index 12 was a mandatory all 6 injectors or nothing step.

[NoGuru]

Correct, you need to change all of them if you are jumping index. Fortunately I have some index 9's sitting on my self. Only upgraded to 12 for preventive so shoot me a PM and I will work out a deal with you.

[Wolf 335]

Originally Posted by Jet-Black

Wolf335
Thank you for your reply. Is that possible? I thought upgrading to Index 12 was a mandatory all 6 injectors or nothing step.

No, it is not mandatory. There are guys on here that ran a mix. Just keep them in the same bank.

Lots of discussion on this. If you have time search 'injectors' on the forum and you will have quite a bit of reading material.

[Jet-Black]

Thank you for sharing what you guys know. I truly, appreciate it.
I just took a look at the price for the Index 12 and even doing 3 of them is not possible for me at this time, because I have already invested all oils, plugs, break pads and such to prep for the upcoming winter. - NoGuru I sent you a PM. -

[TheMidnightNarwhal]

Originally Posted by Wolf 335

No, it is not mandatory. There are guys on here that ran a mix. Just keep them in the same bank.

Lots of discussion on this. If you have time search 'injectors' on the forum and you will have quite a bit of reading material.

Even then I think this whole thing came up as a myth/assumption from what I've concluded from my research.

Couldn't find any info in TIS about not mixing and know a guy locally who ran his car with 5 8s and one index 12.

[Jet-Black]

hmm! Interesting.
- Thinking about it from an electro-mechanical stand point, and the little I know about them, it seems to me that the Injectors do not "talk back" to the ECU, they "act /respond" to instructions. Hence, The ECU is commanding the mixtures via its own readings from different sensors and orders individual injectors to act accordingly. Under this basic analysis, it sounds that Bank Isolation is not unreasonable.

[Jet-Black]

I have resolved the injector sourcing issue I was having.
My immense gratitude to NoGuru for all his help getting me his INDEX9s so quickly (My stress level was about to make me pop), it was a wonderful experience connecting with you.

Also, thank you to Wolf335 and TheMidnightNarwhal who shimmed in with knowledge; and lastly thank you to the administrators of E90 forum for running and maintaining this platform of knowledge, discussions and help!

We got a great bunch here! 