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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N55 Turbo Engine Tuning and Exhaust Modifications - 335i Tuning > N55 Lean Issues



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      02-11-2020, 02:15 PM   #1
Versauce
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N55 Lean Issues

Hey guys,

This is my first post, so hopefully I have this in the right place. My 2011 335i w/ 88k miles (MHD Stage 1+, 91 tune running 92 octane) seems to be running lean. I had shadow codes related to the HPFP back in December in which I replaced it with a remanufactured from ECS Tuning along with the rail pressure sensor. Recently I've been getting lean codes 2BC0, 2C42, accompanied with infrequent stalling at a stop, idle fluctuation/surging (not large increments). I ran a smoke test and only found smoke seeping from the air intake hose that connects to the turbo inlet. I've ordered a replacement gasket for that connection.

Spark plugs are under 5k being one-step colder. I dont know if coil packs or injectors were replaced before my ownership.

MHD data logs for a few pulls below.

https://datazap.me/u/versauce/log-1
https://datazap.me/u/versauce/log-2

Any help is greatly appreciated.
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      02-11-2020, 08:15 PM   #2
TunafishE93
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If you flash back to stock do your errors clear and stay cleared .. What I am getting at is the MHD might be the problem...

You do have a lot of correction on cylinder 2 I would look into.. Swapping coils and plug see if issue follows..

But your stalling and error from what I have seen points to MHD..
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      02-12-2020, 07:57 AM   #3
TheGoodTheBadTheUgly
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I noticed a couple of things when comparing to my Stage 1+ logs.

First off, your air to fuel ratio isn't really pointing towards a big lean state. I mean it is a bit on the high sides compared to the norms but it wouldn't be enough to tip us towards something.

The long term fuel trim is at an average of -7.5 which is acceptable since it's under -10%, but it is suggesting that the PCM is correcting by leaning out the system because it's thinking it's too rich.

This brings me to your MAF reading. On Stage 2+ and Stage 1+ for me, my MAF tappers around 285 g/s while yours stops at around 250 g/s. I don't know if this has a big or negligible impact on the fuel trims but it's just something I noted.

Just a couple of things I noted, but that don't mean much. I would start maybe by doing simple stuff like resetting adaptations.
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      02-12-2020, 08:54 AM   #4
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The lean conditions that I seen where not under load.. It was under normal running before the pull started.. The pull itself didn't look bad for air fuel mixture.. What I have read it a know problem with the MHD and n55 platform.. Easy to see just flash back to stock..
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      02-12-2020, 09:22 AM   #5
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Quote:
Originally Posted by TunafishE93 View Post
The lean conditions that I seen where not under load.. It was under normal running before the pull started.. The pull itself didn't look bad for air fuel mixture.. What I have read it a know problem with the MHD and n55 platform.. Easy to see just flash back to stock..
Idle lean codes usually point to a vacuum leak. Take a log at idle and note what your STFT are. IF they are way positive and AFR is leaning out then it's likely a vacuum leak (like the inlet pipe). Un-metered air is entering the system. Vacuum leak may also present as a boost leak under boost if it's a charge-pipe or something like that.
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      02-13-2020, 10:21 AM   #6
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So I tried flashing to stock, same issue persisted. I removed MHD completely, same thing. That then brought me to the MAF suggestion. I unplugged the MAF and drove the rest of the day with it disconnected. Off the bat I noticed the car ran much smoother. I did a log on my way home last night and it appears fuel trims look better? Along with less timing corrections.

I still have concerns about my boost but with the MAF off I was closer to where it should be. I still think I need a new boost solenoid. I did also install the turbo inlet gasket last night.

https://datazap.me/u/versauce/log-15...og=0&data=3-12
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      02-13-2020, 10:47 AM   #7
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MAF is a parity check against speed density (TMAP vs throttle position).

By disconnecting it, you told the DME to pound sand when it comes to checking metered air vs speed density lookup.

Additionally, you're maxing out STFT in your log (20%) - stop it. Listen to other people. Don't be a dummy.

Thanks for skimping out on the log parameters. Your starting fuel pressure is a bit higher than what it should be - ~2930psi vs ~2750psi. It then tapers off to what it should be at 5000rpm (2450psi).

You're still experiencing some pre-igniton, but it's not extreme, just stuff I would want to tune out. Cyl 5 is noisy, so its just -3 in a few places.

I can't give any insight on this. You're experiencing a lean condition - period. I doubt it is a "vacuum leak" since this is underboost; you would be seeing a rich condition if there was a boost leak (with MAF). Without MAF, you're just getting incorrect fueling, period.

What is your history on TMAP / MAF? any changes?

Quote:
Originally Posted by Versauce View Post
So I tried flashing to stock, same issue persisted. I removed MHD completely, same thing. That then brought me to the MAF suggestion. I unplugged the MAF and drove the rest of the day with it disconnected. Off the bat I noticed the car ran much smoother. I did a log on my way home last night and it appears fuel trims look better? Along with less timing corrections.

I still have concerns about my boost but with the MAF off I was closer to where it should be. I still think I need a new boost solenoid. I did also install the turbo inlet gasket last night.

https://datazap.me/u/versauce/log-15...og=0&data=3-12
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      02-14-2020, 03:17 PM   #8
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Quote:
Originally Posted by anjuna View Post
I can't give any insight on this. You're experiencing a lean condition - period. I doubt it is a "vacuum leak" since this is underboost; you would be seeing a rich condition if there was a boost leak (with MAF). Without MAF, you're just getting incorrect fueling, period.
He is not popping a lean code because of that log. Trims aren't maxed out just yet and AFR is in check. Not saying the log is good but clarifying that he is popping a lean code at idle under vacumm. He already said his intake plenum was loose during smoke testing and that very well could be an issue (unmetered air post MAF). Vacumm leak not meaning a vacumm line but rather umetered air entering the system... pcv valve in valve cover, oil fill cap, loose charge pipe, loose intake piping... all places air will be pulled in while coasting or at idle when the system is under vacumm. Loose charge-pipe being something that would then cause a boost leak under load.

OP, did you fix the intake piping? did you take a log at idle like requested?

Last edited by bbnks2; 02-14-2020 at 03:23 PM..
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      04-27-2020, 12:03 PM   #9
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Any Fix yet???
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      04-27-2020, 02:00 PM   #10
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Quote:
Originally Posted by Versauce View Post
So I tried flashing to stock, same issue persisted. I removed MHD completely, same thing. That then brought me to the MAF suggestion. I unplugged the MAF and drove the rest of the day with it disconnected. Off the bat I noticed the car ran much smoother. I did a log on my way home last night and it appears fuel trims look better? Along with less timing corrections.

I still have concerns about my boost but with the MAF off I was closer to where it should be. I still think I need a new boost solenoid. I did also install the turbo inlet gasket last night.

https://datazap.me/u/versauce/log-15...og=0&data=3-12

Replace the maf sensor ...
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      10-14-2023, 12:00 PM   #11
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Quote:
Originally Posted by Versauce View Post
So I tried flashing to stock, same issue persisted. I removed MHD completely, same thing. That then brought me to the MAF suggestion. I unplugged the MAF and drove the rest of the day with it disconnected. Off the bat I noticed the car ran much smoother. I did a log on my way home last night and it appears fuel trims look better? Along with less timing corrections.

I still have concerns about my boost but with the MAF off I was closer to where it should be. I still think I need a new boost solenoid. I did also install the turbo inlet gasket last night.

https://datazap.me/u/versauce/log-15...og=0&data=3-12

Any updates? Also what codes were you getting exactly?
Im getting these following codes-
2BCB
2D2F (Shadow)
And 2D34 after replacing upstream o2 sensor.

N55 with FBO, mhd stage 0 tune.
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      10-14-2023, 04:26 PM   #12
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Quote:
Originally Posted by EnzoKhan View Post
Any updates? Also what codes were you getting exactly?
Im getting these following codes-
2BCB
2D2F (Shadow)
And 2D34 after replacing upstream o2 sensor.

N55 with FBO, mhd stage 0 tune.
The shadow code is normal for the downpipe. I have them too and MHD suppresses them.
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      10-14-2023, 06:52 PM   #13
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Quote:
Originally Posted by MakoB96 View Post
The shadow code is normal for the downpipe. I have them too and MHD suppresses them.
That's definitely good to hear! How about the other codes? I was getting the 2D2F code, mixture control after catalytic too lean. So I replaced the upstream sensor, now it says the upstream sensor is fixed at rich (2d34 code), while the post o2 is still saying lean.

Here is a log: https://datazap.me/u/enayet/partial-...ta=11-14-15-19

Getting around 14.6 AFR at full throttle, and some timing corrections. Let me know your thoughts! Thanks!
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      10-17-2023, 01:16 PM   #14
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Quote:
Originally Posted by EnzoKhan View Post
That's definitely good to hear! How about the other codes? I was getting the 2D2F code, mixture control after catalytic too lean. So I replaced the upstream sensor, now it says the upstream sensor is fixed at rich (2d34 code), while the post o2 is still saying lean.

Here is a log: https://datazap.me/u/enayet/partial-...ta=11-14-15-19

Getting around 14.6 AFR at full throttle, and some timing corrections. Let me know your thoughts! Thanks!
I think to remedy the mixture control after cat code you would have to change the 02 sensor on your downpipe.
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      10-17-2023, 01:18 PM   #15
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Quote:
Originally Posted by EnzoKhan View Post
That's definitely good to hear! How about the other codes? I was getting the 2D2F code, mixture control after catalytic too lean. So I replaced the upstream sensor, now it says the upstream sensor is fixed at rich (2d34 code), while the post o2 is still saying lean.

Here is a log: https://datazap.me/u/enayet/partial-...ta=11-14-15-19

Getting around 14.6 AFR at full throttle, and some timing corrections. Let me know your thoughts! Thanks!
I would also advise to refrain from doing WOT pulls in 3rd gear from 2k RPM, 3k RPM minimum or you're overworking the turbos.
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      10-17-2023, 01:24 PM   #16
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Quote:
Originally Posted by EnzoKhan View Post
That's definitely good to hear! How about the other codes? I was getting the 2D2F code, mixture control after catalytic too lean. So I replaced the upstream sensor, now it says the upstream sensor is fixed at rich (2d34 code), while the post o2 is still saying lean.

Here is a log: https://datazap.me/u/enayet/partial-...ta=11-14-15-19

Getting around 14.6 AFR at full throttle, and some timing corrections. Let me know your thoughts! Thanks!
Also are you on stage 0???
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      10-17-2023, 01:26 PM   #17
SlowE92
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Quote:
Originally Posted by EnzoKhan View Post
That's definitely good to hear! How about the other codes? I was getting the 2D2F code, mixture control after catalytic too lean. So I replaced the upstream sensor, now it says the upstream sensor is fixed at rich (2d34 code), while the post o2 is still saying lean.

Here is a log: https://datazap.me/u/enayet/partial-...ta=11-14-15-19

Getting around 14.6 AFR at full throttle, and some timing corrections. Let me know your thoughts! Thanks!
What fuel are you running?
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      10-19-2023, 10:26 AM   #18
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Quote:
Originally Posted by MakoB96 View Post
What fuel are you running?
Yes I am on stage 0 and running 93 octane.
I bought the car with a stage 0 tune and full bolt-on.
-Catless downpipe
-cold air intake
-7.5 in intercooler

The previous owner had it in MHD stage 2+ tune but set it to stage 0 when selling.
I have driven about 10,000 miles since I bought it in stage 0. I recently purchased the MHD super license to monitor the car and tune it eventually.

What do you think could be the reason behind the turbo overworking?

I appreciate your response!
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      10-19-2023, 04:23 PM   #19
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Quote:
Originally Posted by EnzoKhan View Post
Yes I am on stage 0 and running 93 octane.
I bought the car with a stage 0 tune and full bolt-on.
-Catless downpipe
-cold air intake
-7.5 in intercooler

The previous owner had it in MHD stage 2+ tune but set it to stage 0 when selling.
I have driven about 10,000 miles since I bought it in stage 0. I recently purchased the MHD super license to monitor the car and tune it eventually.

What do you think could be the reason behind the turbo overworking?

I appreciate your response!
Well to my understanding is stage 0 works as the stock map. If the previous owner flashed stage 0, you would need to go in and do a reflash. Your DME is attempting to read your cats, and MHD isn't suppressing the codes. Flash one of the stages and see if that clears your code. It'll appear as a shadow code and not an active one.
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      10-19-2023, 04:44 PM   #20
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Quote:
Originally Posted by EnzoKhan View Post
Yes I am on stage 0 and running 93 octane.
I bought the car with a stage 0 tune and full bolt-on.
-Catless downpipe
-cold air intake
-7.5 in intercooler

The previous owner had it in MHD stage 2+ tune but set it to stage 0 when selling.
I have driven about 10,000 miles since I bought it in stage 0. I recently purchased the MHD super license to monitor the car and tune it eventually.

What do you think could be the reason behind the turbo overworking?

I appreciate your response!
Also scratch what I said about the 3rd gear pull I forgot 2k RPM 3rd gear for a log lol.
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