[lukavergille]

Hello, i had my car with engine mechanic for checking and when he took the fuel injectors off he didn’t put them back in the same place where they were initially (1st injector was put in place of 3rd and so on). I have read somewhere that fuel injectors need reprogramming after replacement and will it be necessary in my case? I didn’t replace them they were just put back in by different order. Might be a stupid question but want to make sure everything is fine..

[Surly73]

Yes it matters. There is a unique flow rate compensation value printed on each injector which must be coded into the ECU.

[lukavergille]

Originally Posted by Surly73

Yes it matters. There is a unique flow rate compensation value printed on each injector which must be coded into the ECU.

Will ISTA tell me the original order of the injectors so i can just replace them back to original order or should i code a new order?

[Hoa]

It does tell you what is currently programmed for which cylinder. If you already installed them back in, you can easily update it so you don’t have to pull them back out.

[lukavergille]

Originally Posted by Hoa

It does tell you what is currently programmed for which cylinder. If you already installed them back in, you can easily update it so you don’t have to pull them back out.

Thanks for help! I was able to look at the codes on first 4 fuel injectors. Based on what ISTA shows Looks like 1st and 2nd are in correct place but 3rd and 4th are swapped. I can’t look at 5th and 6th injectors because they are covered by intake or something. Is there any way i can check if those 5th and 6th injectors are correctly put with ISTA or will i need to take of covers to actually see the codes on those injectors?
Also shouldn’t I be getting errors becuase of misplaced 3rd and 4th injectors?

[lukavergille]

I did misfire test on ISTA and it showed that there was misfire on Cylinder 3 and 5 when starting the engine. Would that mean that Injectors 5-6 are swapped too as 3-4 are?

[Trian]

1 + 1 = 2 ?

Or in other words, don't overthink things

[Hoa]

I don’t think it would throw any error code. It just wouldn’t spray efficiently

[lukavergille]

Just confirmed that 5-6 are correct by mechanic. So i will just calibrate 3rd and 4th injectors. Should i reset adaptions after calibration?

[Surly73]

As others said - you can recode the values into the DME (should have stated that in my post). You just wouldn't have to if they were inserted back in the correct spot. If they are mis-coded it will affect smooth idling etc...

Now - if your mechanic didn't know to put them back in the same place, do they know about the single-use parts and specific insertion tools/technique for the injectors? That would be my question.

[lukavergille]

Originally Posted by Surly73

As others said - you can recode the values into the DME (should have stated that in my post). You just wouldn't have to if they were inserted back in the correct spot. If they are mis-coded it will affect smooth idling etc...

Now - if your mechanic didn't know to put them back in the same place, do they know about the single-use parts and specific insertion tools/technique for the injectors? That would be my question.

Unfortunately he didn’t know any of that…
I just found out about special insertion tools and technique.
Th single-use parts - are you refering to decouplers and injection seals? He definitely hasn’t replaced them or anything else. Just took the injectors out for few minutes to check something and put them back in. So these single-use parts should be replaced even if injector was just taken out and put back in?

[Surly73]

Originally Posted by lukavergille

Unfortunately he didn’t know any of that…
I just found out about special insertion tools and technique.
Th single-use parts - are you refering to decouplers and injection seals? He definitely hasn’t replaced them or anything else. Just took the injectors out for few minutes to check something and put them back in. So these single-use parts should be replaced even if injector was just taken out and put back in?

Yep - if you want to do the job by the book... Also need to pay attention to the injector removal tool and the maximum torque/pull on the injectors before they are considered ruined and need to be discarded. When you use the pulling tool you're supposed to use a torque wrench set for 5Nm (almost nothing) and if it clicks the injector is toast. And then other guys on Youtube just yank.

Some may say that the repair manual is too fussy and Mr. X has done Y and Z without doing any of the stuff in the manual, but these engines can be pretty picky.

Can't link you to real factory manuals any more but this seems to have a lot of the stuff:

https://bmwrepairguide.com/bmw-n55-f...r-replacement/

Note that the N55 has 3 styles of injectors: broadly they are EU5 or EU6, and within EU5 there is gen 1 and gen 2. Different puller tools, appearance and, obviously, parts required if you do the swap.