technical bmw 335i n55 pwg running lean

[Liam H]

Hey everyone

So for a while my car has been having an obvious vaccuum leak and my pcv gave in (squeeling noise and car running lean), therefor i took the car to bmw and they replace my valve cover. Fast forward about 3 days after today and my car is still running lean on my data logs and the car starts quite rough on cold starts, the car also gets some terrible timing corrections, up to 8 degrees.

Has anyone has any issues like this on an N55? I'm taking the car Monday to have a smoke test done to see what's going on. Before the valve cover (pcv) was replace my car gave a "102001 - Air volume, plausibility: Air volume too high." code, which was obvious from unmeasured entering the engine, After the fix, I have not gotten the code again but still very high LTFT % figures, especially on idle.

The car has an upgraded aluminum charge pipe and catless downpipe. The car was running on just a Stage 1 MHD tune but i flashed the car back to stock power figures or "Stage 0" because the car is obviously not running right.

If anyone can help me point out some things to look out for to look at please let me know. I will be posting screenshots and a Datalog link for everyone to look at and to help me know that this is a vaccuum leak and that this would hopefully not destroy my bank account

TIA

2012 F30 335i N55 PWG

Data Logs Links

datazap.me | Liam Hansen | Lean idle

datazap.me

datazap.me | Liam Hansen | idle 2

datazap.me

datazap.me | Liam Hansen | wot w timing corr

datazap.me

datazap.me | Liam Hansen | cruising ltft

datazap.me

 

[Pisancho]

I respect the whole learning thing you are doing but I would just pick a trusted mechanic or shop and take it there.

Unless you want to become a tech, it is far cheaper and easier to just take it in. It’s an expensive exercise replacing things and hoping to get a problem fixed.

 

[Liam H]

I respect the whole learning thing you are doing but I would just pick a trusted mechanic or shop and take it there.

Unless you want to become a tech, it is far cheaper and easier to just take it in. It’s an expensive exercise replacing things and hoping to get a problem fixed.

Absolutely, I'm taking the car in tomorrow for a smoke test.

 

[Teezoh]

Oh dear...

If I can give you advice, stop it right now

The road of checking data logs, possibly this, possibly that, leads to a very dark cabin in the woods with no furniture or sunlight, just an old, uncomfortable, creaking chair in the corner, with the smell of wet wood and a few random crows that can be heard but never seen...

The short answer:

Listen to @Pisancho, take the car to a trusted mechanic, tell him what's wrong with it without mentioning ANYTHING you think you know. It should be a short, straightforward summary, try and act normal, I know it's hard.

The data log addict answer:

A vacuum leak is suspected. The fuel trim at idle and lean spikes at low load strongly indicate unmetered air. This can be anything from the charge pipe, diverter valve, intake manifold gaskets, valve‑cover (Yes, I know you just had this done, I've had a valve cover replaced that was never torqued to spec, and it caused problems), etc etc etc

Check cylinder 2 ignition and fuel. During the WOT pull, the ECU repeatedly pulled 2 to 6 degrees of timing in cylinder 2, indicating knock control intervention. While this could also be caused by the shit fuel we have, you should ALWAYS be mixing at least 10% eth at the bare minimum when running a tune on these motors to eliminate that as a possible cause. You can also replace spark plugs and swap the ignition coil from cylinder 2 to another cylinder to see if the knock migrates.

Always reset adaptations after repairs. Clear the fuel‑trim adaptations and perform a fresh learning cycle. This is a must and only takes you 10 seconds. I can't stress this enough, as I've sat with random fuel-trim gremlins that simply go away after resetting adaptations.

Why I'm saying you should stop now, the signs are there, I know, I've been there:

Fast forward about 3 days after today

Bro is data logging so hard that he unlocked time travel...

 

[Liam H]

Oh dear...

If I can give you advice, stop it right now

The road of checking data logs, possibly this, possibly that, leads to a very dark cabin in the woods with no furniture or sunlight, just an old, uncomfortable, creaking chair in the corner, with the smell of wet wood and a few random crows that can be heard but never seen...

The short answer:

Listen to @Pisancho, take the car to a trusted mechanic, tell him what's wrong with it without mentioning ANYTHING you think you know. It should be a short, straightforward summary, try and act normal, I know it's hard.

The data log addict answer:

A vacuum leak is suspected. The fuel trim at idle and lean spikes at low load strongly indicate unmetered air. This can be anything from the charge pipe, diverter valve, intake manifold gaskets, valve‑cover (Yes, I know you just had this done, I've had a valve cover replaced that was never torqued to spec, and it caused problems), etc etc etc

Check cylinder 2 ignition and fuel. During the WOT pull, the ECU repeatedly pulled 2 to 6 degrees of timing in cylinder 2, indicating knock control intervention. While this could also be caused by the shit fuel we have, you should ALWAYS be mixing at least 10% eth at the bare minimum when running a tune on these motors to eliminate that as a possible cause. You can also replace spark plugs and swap the ignition coil from cylinder 2 to another cylinder to see if the knock migrates.

Always reset adaptations after repairs. Clear the fuel‑trim adaptations and perform a fresh learning cycle. This is a must and only takes you 10 seconds. I can't stress this enough, as I've sat with random fuel-trim gremlins that simply go away after resetting adaptations.

Why I'm saying you should stop now, the signs are there, I know, I've been there:


Bro is data logging so hard that he unlocked time travel...

I went for the vacuum leak today, absolutely nothing, I am quite stunned and I know its not a pcv issue as i have a brand new valve cover fitted a week ago by bmw. I will talk to the guy you sent me the number of. I also talked to some guys on other forums and they can't see anything alarming about the logs. And also, car is giving no codes at all. Scanned with multiple diagnostic tools, nothing.

 

[Teezoh]

I went for the vacuum leak today, absolutely nothing, I am quite stunned and I know its not a pcv issue as i have a brand new valve cover fitted a week ago by bmw. I will talk to the guy you sent me the number of. I also talked to some guys on other forums and they can't see anything alarming about the logs. And also, car is giving no codes at all. Scanned with multiple diagnostic tools, nothing.

With that out the way your MAF sensor could be dirty or out‑of‑calibration or your oxygen sensors might have become lazy throwing your DME off a little, once again all just possibilities.

Did they check the brake‑booster hose, crankcase vent lines or around the throttle body gasket too? I'm guessing they did a smoke test?

You have access to MHD, try resetting the adaptations and let the trims re-learn, will take you a few seconds and just let it run for the day while you wait for your next steps.

 

[Liam H]

With that out the way your MAF sensor could be dirty or out‑of‑calibration or your oxygen sensors might have become lazy throwing your DME off a little, once again all just possibilities.

Did they check the brake‑booster hose, crankcase vent lines or around the throttle body gasket too? I'm guessing they did a smoke test?

You have access to MHD, try resetting the adaptations and let the trims re-learn, will take you a few seconds and just let it run for the day while you wait for your next steps.

They did a full smoke test, boost pipes, intake, chargepipes and pcv hoses, nothing