This time – a popular theme: what to do, if you have to replace the injector, but at the same bank, there are still some (or all others) injectors with another (obviously, older) release. Do the older injectors(s) should be replaced too? Or all injectors of the current bank should be replaced, not depending on the release?

In their materials, BMW (not indicating specifically regarding releases) says: if there is a problem with one cylinder (misfires, it gets turned off, etc.), the current cylinder’s injector should be replaced. If there are problems with at least 2 cylinders of the bank, all injectors of the corresponding bank should be replaced. 

Instead, on the Internet, I have seen the instructions regarding releases – replace all injectors, which are not of the actual release. 

I instead recommend replacing only the injector, which is performing poorly. And the injectors, who are older than the 4th release. Why so different opinions?

I have read several strange versions on the Internet, for example:

a. parameters of the injectors are significantly different – if all injectors are not of the same release, the engine will vibrate, shiver;

b. the “old” injectors will have additional load after installing some with a newer release, so they will get damaged and need to be replaced soon.

No, unfortunately – nothing like that. But, what is the truth?

The fundamental difference is, in a way, how works the BMW dealer, and how I work. What is this difference?

Dealer has huge expenses, which should be covered – office premises, secretaries, service recipients, managers, etc. The dealer has no time desire and even possibilities to “go into” each exact (sorry, used – in the dealer’s opinion – old) car nuances. Dealer has no possibilities (again – time, personal, extra diagnostics sets) to perform the test drives. 

And even more – the dealer has no access to a range of MEGA important information:

a. misfire counters data via OBD Mode 6;

b. injector adaptation data, which can be seen only in INPA. As we know, INPA is not allowed in the dealer centers.  

These are the arguments why it is recommended for dealers to replace all old injectors and all injectors of the same bank if it is harder to identify the problem. Time is money – so simple. In addition, it is ancient if the injector is not of the actual release (11th release for N43/N53series engines and 12th release for N54 series engines). Ancient – 10 years. If the customer has gone to the dealer center (not to the max cheap underground workshop), he obviously wants a perfect engine performance. If the injector data are not available, how can the dealer ensure the result? Only – replacing all injectors with a justified reason! Older release? Let’s replace! We can’t detect the cause of the problem? Let’s replace! And I don’t even condemn it too much because that is a business. The dealer earns money by selling new cars, and basically, on warranty maintenance. The dealer does not need 10 years old cars with mileage over 200.00 km that sometimes have “some vibration”.

In the old past, BMW organized the recall campaign till 4th release. It means the manufacturer replaced the injectors without charge. I have no objective information, were these old injectors really so bad, but I believe – if the injector is at least 12 .. 13 years old, then… Then it should be replaced when you perform the repair – you can not trust them anymore. And maybe the time has come to make some investments in the car, because for sure – the car was not maintained very well even in the warranty period (otherwise, if the car would be visiting the dealer center, the old releases of the injectors would be replaced a long time ago without charge). 

And finally, regarding previously mentioned versions.

a. parameters of the injectors are significantly different – if all injectors are not of the same release, the engine will vibrate, shiver;

No, it will not shiver. “Floating” of the injector parameters during their lifetime (and when the work condition, temperature, Rail pressure, etc., changes) changes much more significant than when releases change. The task of DME, instead, is – using the individual adaptations (their multidimensional adaptation maps), even the performance of the injectors in all performance modes.

b. the “old” injectors will have additional load after installing some with a newer release, so they will get damaged and need to be replaced.

It is hard to oppose this because the statement itself is technically idiotic. Needless to say, I haven’t got any more exact explanation from the authors of these ideas. The only one – “I replaced the injector, after a moment the engine vibrated again, I had to replace other injectors too”. My skeptical opinion – obviously, the initial defect was not indicated correctly. Or – already before the replacement, there were problems with other injectors too. Why? It is possible that low-quality fuel was used. 

In any case – for the injector replacement to give a positive result:

a. all injectors should be encoded correctly;

b. the readaptation of the injectors should be done correctly; 

c. DME should work in full functionality mode.

Note: DME works in full functionality mode only when/if all its systems work correctly (including NOx system for N43/N53 series engines; also as if completely unrelated systems, for example: thermal management, battery/IBS system, etc., also – the DME error message memory has no error messages).  

I had done lab work, which convincingly proves, that the performance of the injectors has no direct correlation with the possibility of damages. It means the injectors are not “aging”. The injector can perform well also for 200 … 300.000 km (all injector adaptations will be perfect; the engine will work perfectly), even more. At the same time – it can start to leak already after several tens of thousands after installation. And using poor quality fuel – even directly after installation.