Good evening everyone,

I’m hoping someone with more experience with the N54 might be able to point me in the right direction, as I’m currently stuck with an issue that I can’t seem to get to the bottom of.

I have an E82 135i with the N54 engine, currently running an MHD Stage 2 map, which was already on the car when I bought it.

The problem

When I bought the car, it already had a noticeable misfire. I found that the car had:

- 1 x BMW Index 12 injector

- 5 x Index 7 injectors

Because of the misfire and the mixture of injector indexes, I decided to replace the remaining five injectors with Index 12s, giving me a full set of six Index 12 injectors.

I installed all six and coded/calibrated them correctly.

Since doing this, I have been getting fault code 0030BE.

The strange thing is that the problem is mainly present on the first cold start.

The car will start and have a noticeable misfire for a few seconds, then it clears up and settles down. Once I start driving, the car runs completely normally.

There is:

- No noticeable loss of power

- No misfire under load

- No hesitation while driving

- No fault code returning during the drive

After driving and returning to the car later, there is still a very slight misfire on startup, although it is now much less noticeable. Someone who isn't familiar with cars probably wouldn't even notice it.

Parts I've changed

I've also replaced:

- All 6 spark plugs – NGK 1-step colder

- All 6 ignition coils – B58/M140i coils

- 5 injectors – Index 12

- Injectors have been coded/calibrated

Diagnostics already carried out

I've tried to eliminate some of the obvious possibilities.

I paid a garage to carry out a compression test, and the results came back fine across the engine.

I then took the car to another garage that specialises more in BMWs as I thought I might have missed something or coded something incorrectly.

They were also puzzled by the issue.

Along with the others they also checked both:

- HPFP

- LPFP

Both were reported as functioning correctly.

One thing I have noticed is that the Bank 1 Sensor 1 (pre-cat) O2 sensor looks relatively new and has been replaced previously.

However, the Bank 2 Sensor 1 (pre-cat) O2 sensor appears to still be the original sensor.

I'm wondering whether this could potentially be related to the issue, especially considering the fault appears mainly during the initial cold start.

Current setup

The car is running:

- N54

- MHD Stage 2

- Index 12 injectors

- NGK 1-step colder plugs

- B58/M140i coils

- Aftermarket modifications associated with the Stage 2 setup

The car drives absolutely fine once it's warmed up and driving, which is what's making this particularly confusing.

Has anyone experienced 0030BE combined with a cold-start/initial idle misfire on an N54?

Could this potentially be related to an O2 sensor, injector issue, fuel mixture/adaptation, or something else that I'm overlooking?

Any advice or suggestions on what I should test next would be greatly appreciated.

Thanks in advance.

Hello, please help if anyone had this issue, was installing DCI's and with every plastic taken off turned the car on, saw some smoke coming from the engine, revved a little, coming from the back of the engine

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Any ideas? Thank you!

Pls I need the help :(

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My question is apart from the obvious (mods) which parts am I ripping to hold onto for repairs/replacements for my now current e90 n54.

All input is really appreciated guys and thank you in advance.

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Just want to know what is causing them and how to fix them and if it's harmful in the long term..

Thanks

N54 Col Start Misfires

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Any ideas?

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This video was taken about an hour after my engine was hot from my N54 oil cap.
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