[iqraceworks]

I have a leaky injector in my 07’ 335i. It’s not really causing any issues, but I’d rather just replace it before it starts to cause problems. I’m pretty sure the injectors that are currently in the car are index 7, but I think there are actually a couple index 4’s thrown in the mix also.

Is there any reason why I can’t just replace that one bad injector with a new index 12 injector instead of replacing all 3 in that bank? I’ve searched the forums, and I’ve found lots of conflicting information.

As long as I code the new injector in with the new power and flow numbers…..would I be ok just replacing one? I’m just wondering……if it’s going to cause issues, I will just replace all three.

[TheMidnightNarwhal]

I've also searched on this and while people claimed all three on one bank had to be the same I've never found any actual reputable sources or data or a BMW document saying so. Nothing in TIS/ISTA either on that.

I coded an injector index 12 of a member here who only put one but he didn't keep his car to long as he sold it after but didn't report any issues in the 2 weeks he had it with one different.

EDIT: Fell on my old post in here ha, basically I stand corrected here's the official documentation : https://static.nhtsa.gov/odi/tsbs/20...29104-4598.pdf

That said only a few months ago Jan 2022, I replaced only one injector to Index 12 while they are all 9s and also have no issues mixing like other members here.

[Salzamani]

Hello again!

Just to give you an update. I replaced only one leaky cylinder 1 injector over 2 months ago. It’s solved my rough idle issues and improved my fuel economy about 10%. My N54 fires up faster than ever not that it ever had an issue. The spark plug now looks dry and clean. I put in an index 12 and coded it using INPA. All of my other 5 injectors are index1’s. The car pulls normal and you would never know that I have mixed injectors because it runs absolutely perfect. Just do it!

[type-dRew]

If I understand it correctly. Each bank can have varying injectors but they either need to be 1->10 or 11->12.

If you have a bank of injectors that have a 7, only 1-10 are able to be used unless you replace all 3 with index 11/12s. This is just what i've read and not personal experience.

[iqraceworks]

Originally Posted by type-dRew

If I understand it correctly. Each bank can have varying injectors but they either need to be 1->10 or 11->12.

If you have a bank of injectors that have a 7, only 1-10 are able to be used unless you replace all 3 with index 11/12s. This is just what i've read and not personal experience.

This is what I've read also.....but it doesn't make sense to me. How does the DME know what index of injector(s) is in the motor? As long as you code it correctly....why would it matter??

And apparently (see posts above)....people have ran an index 12 injector in the same bank with older injectors (index 1-10) and had no issues.

Unfortunately.....like many things N54 related, there is a ton of conflicting info out on the forums.

[TheMidnightNarwhal]

Originally Posted by iqraceworks

This is what I've read also.....but it doesn't make sense to me. How does the DME know what index of injector(s) is in the motor? As long as you code it correctly....why would it matter??

And apparently (see posts above)....people have ran an index 12 injector in the same bank with older injectors (index 1-10) and had no issues.

Unfortunately.....like many things N54 related, there is a ton of conflicting info out on the forums.

I'd say send it with one and see what happens, if you are DIYing. That way don't have to pay labor twice.

[Silent9n54]

Originally Posted by Salzamani

Hello again!

Just to give you an update. I replaced only one leaky cylinder 1 injector over 2 months ago. It’s solved my rough idle issues and improved my fuel economy about 10%. My N54 fires up faster than ever not that it ever had an issue. The spark plug now looks dry and clean. I put in an index 12 and coded it using INPA. All of my other 5 injectors are index1’s. The car pulls normal and you would never know that I have mixed injectors because it runs absolutely perfect. Just do it!

are you tuned ??

[iqraceworks]

Originally Posted by TheMidnightNarwhal

I'd say send it with one and see what happens, if you are DIYing. That way don't have to pay labor twice.

Yep...that's the plan. I'm coding them in myself....so it's not a big deal if I have to order two more.

[Shoooter_j]

Originally Posted by Salzamani

Hello again!

Just to give you an update. I replaced only one leaky cylinder 1 injector over 2 months ago. It’s solved my rough idle issues and improved my fuel economy about 10%. My N54 fires up faster than ever not that it ever had an issue. The spark plug now looks dry and clean. I put in an index 12 and coded it using INPA. All of my other 5 injectors are index1’s. The car pulls normal and you would never know that I have mixed injectors because it runs absolutely perfect. Just do it!

I’m in the exact same boat. Replaced Cylinder 1 injector with index 12, with the rest index 1 - been running like a dream for 6k miles 👍 I’m FBO + Protune (no inlets)

[Salzamani]

Originally Posted by Silent11N54

are you tuned ??

No I’m not tuned and even if I was I would have still done it this way and if after doing it the car ran funny as a result of it then I would act accordingly. It’s not rocket science, if there is something wrong the car will run like shit...

I think all this stuff about not mixing injectors index 1-10 with 11 & 12’s in the same bank is a bunch of baloney. My mix is doing just fine and many others that have done it report the same. As a matter of fact I’ve never came across anyone that had a problem doing so. The only people that tell you not to do it are paranoid people that just take others words for it and have extra money to waist .Only the people that didn’t actually mix them and just trust what others say are feeding the fire of don’t mix...

My car never ran better, the fuel economy is better than ever and it pulls very strong. I’ve own 2 N54 cars so I have a grasp on what these cars should run like..

[Salzamani]

Originally Posted by Shoooter_j

I’m in the exact same boat. Replaced Cylinder 1 injector with index 12, with the rest index 1 - been running like a dream for 6k miles 👍 I’m FBO + Protune (no inlets)

Yeah I’m not surprised. I think it is just BMW’s ploy to sell more injectors to help recoop some of the cost of all of those warranty exchanges...

[iqraceworks]

Well, I just ordered one Index 12 injector from FCP Euro for $229........I'll let everyone know how mixing an index 12 in with two index 7's works.

I'm guessing that as long as I code it in, I'm not going to have any issues at all.



On a side note....has anyone tried the refurbished injectors FCP is selling for $159? They have the same lifetime warranty...I wonder if they are worth the money you save?

[IllSic_Design]

Originally Posted by iqraceworks

On a side note....has anyone tried the refurbished injectors FCP is selling for $159? They have the same lifetime warranty...I wonder if they are worth the money you save?

You have to send in an Index 12 injector for the core otherwise you get charged the core charge and it equals out or is more than buying a new one.

[iqraceworks]

Originally Posted by IllSic_Design

You have to send in an Index 12 injector for the core otherwise you get charged the core charge and it equals out or is more than buying a new one.

That's nuts.....sounds like it's really not that great of a deal then.

[Salzamani]

Originally Posted by iqraceworks

Well, I just ordered one Index 12 injector from FCP Euro for $229........I'll let everyone know how mixing an index 12 in with two index 7's works.

I'm guessing that as long as I code it in, I'm not going to have any issues at all.



On a side note....has anyone tried the refurbished injectors FCP is selling for $159? They have the same lifetime warranty...I wonder if they are worth the money you save?

As I mentioned before in other threads, this is the index12 injector that I installed in my N54. Yes it is a used remanufactured injector. I looked closely into this Ebay seller’s feedback results on this injector in particular and the seller is spotless. They are legit genuine Siemens index12 Injectors. I even spoke to him on the phone and he answered all of my question to make me feel comfortable. That injector is mixed with my 5 index 1’s and has been absolutely perfect. Having/owning this index 12 injector also opens me up to potentially using it as a core to purchase future remanufactured injectors from FCP. This Ebay seller does take offers as well. I got mine for $90. Here is the link

https://www.ebay.com/itm/OEM-FUEL-IN...-/262399013193


I figure like this. My original index 1 injectors have lasted me for 70k miles and 12 years and 5 of them are still going strong. There has been many updates to these injectors in an effort to improve them. Any index 12 injector, even used is likely to be in much better condition than my 12 year old injectors... why not just buy 1 yes used index12 injector to replace the one bad injector that I have and if it lasts me 2-5 years than that’s long enough for me to decide whether or not I’ll even keep this car that long. Just running out and replacing 6 injectors for $1400 that money will not be recovered if I ever sell the car. Gotta keep things sensible. The value of the car doesn’t support spending $1400 for a part and that beings a good decision. we may think we want to keep these cars for 10-15 years longer but statistics show that is very unlikely. That’s why FCP is successful.

[JM98]

Yes, it can be done without issue.

[iqraceworks]

I've heard that the calibration numbers printed on the reman injectors aren't accurate...because they have been rebuilt, and the flow rates changed. Any truth to that?

[georgelb]

Originally Posted by iqraceworks

Is there any reason why I can’t just replace that one bad injector with a new index 12 injector instead of replacing all 3 in that bank? I’ve searched the forums, and I’ve found lots of conflicting information.

Index 11 and over injectors are calibrated and constructed differently than 10 and under. Meaning, even when correctly coded, mixed injectors (mixing 10 and under and 11 and over) on the same bank will interpret the signals from the DME differently.

Here's the SIB: https://static.nhtsa.gov/odi/tsbs/20...29104-4598.pdf

[iqraceworks]

Originally Posted by georgelb

Index 11 and over injectors are calibrated and constructed differently than 10 and under. Meaning, even when correctly coded, mixed injectors (mixing 10 and under and 11 and over) on the same bank will interpret the signals from the DME differently.

Here's the SIB: https://static.nhtsa.gov/odi/tsbs/20...29104-4598.pdf

This doesn't make sense to me. When they develop the calibration numbers for each injector (power and flow)......don't they use the same base input signal for doing that? In other words....if the index 12 injector gives more or less fuel than the index 10 (or under) injector....wouldn't that be reflected in the calibration numbers....and coded into the DME?

So the end result would be two injectors that flow the same about of fuel given the same signal....because the different calibration numbers even everything out?

The SIB says that "Index 11 and higher injector have a different calibration number".......but don't they all have different calibration numbers? Isn't that the whole point of having "calibration numbers"?

I'm just trying to wrap my head around the logic......

[Salzamani]

Originally Posted by iqraceworks

I've heard that the calibration numbers printed on the reman injectors aren't accurate...because they have been rebuilt, and the flow rates changed. Any truth to that?

Yes there are counterfeit injectors that are mass produced with the same flow rate stamped on the injectors. I was very concerned when purchasing that injector that I gave the link to above. That is not what this Ebay seller is selling. I looked into his business and where he operated out of in New York and tracked down the phone number and spoke with him. He was also familiar with the counterfeit injectors that was being sold and assured me that that was not what he was selling. He assured me that his injectors all had different flow rates and told me where his source was to acquiring these injectors. Despite all of this I was scriptable until I received it, installed it and fired up the engine. Took her for a spin, came back and pulled the same spark plug on that cylinder 1 that had the fouled plug and to my shocking surprise after only a 10 min drive the plug was already 90% free of any fouling. At that point I knew the injector was legit. Over the course of the past 2 months I’ve been measuring my fuel economy and that too has improved about 10%. Incidentally I did use INPA to code the index12 injector. It took less than a minute to do that.

Here is a link to the post I made about my leaky idex1 injector. it includes pics of the foiled cylinder 1 spark plug.

https://www.e90post.com/forums/showthread.php?t=1648124

[georgelb]

Originally Posted by iqraceworks

This doesn't make sense to me. When they develop the calibration numbers for each injector (power and flow)......don't they use the same base input signal for doing that? In other words....if the index 12 injector gives more or less fuel than the index 10 (or under) injector....wouldn't that be reflected in the calibration numbers....and coded into the DME?

So the end result would be two injectors that flow the same about of fuel given the same signal....because the different calibration numbers even everything out?

The SIB says that "Index 11 and higher injector have a different calibration number".......but don't they all have different calibration numbers? Isn't that the whole point of having "calibration numbers"?

I'm just trying to wrap my head around the logic......

I'm not a BMW tech, but what I infer from that SIB, and the fact that up through index 10 mixing didn't matter, is that something fundamentally changed in the construction and calibration of index 11 injectors, and that this change could cause issues if mixed with prior revisions.

[Salzamani]

Originally Posted by georgelb

I'm not a BMW tech, but what I infer from that SIB, and the fact that up through index 10 mixing didn't matter, is that something fundamentally changed in the construction and calibration of index 11 injectors, and that this change could cause issues if mixed with prior revisions.

Maybe there are other factors such as HPFP or others in what may cause some vehicles to potentially need all 3 injectors replaced in that bank with index11 or higher. I think even BMW doesn’t know. In my case I had a rough idle, the engine would constantly miss. That spark plug was black and my fuel economy was around 20 mpg. All I did was throw in 1 index12 in cylinder 1 and all the rest remained index1’s. Upon first start the change was like night and day. It ran smooth as butter at idle. The test drive was flawless it pulled very strong. No engine codes. Fuel economy is up now about 22-23mpg despite the more spirited driving. No one can convince me that my car needs to have all index12’s the way it has been running for the past 2 months. Now if something changes or I’m wrong in any way I’m not the type to be too proud to admit it. I will report back.