[as473]

Hey all. First time post long time lurker. Posted this on Facebook however thought I'd ask the folks on here too. Having some scary lean conditions on my e92 335i running 98 Oct MHD stg 2+. I'm fairly new to the platform and am in desperate need of advice on this worrying issue. Car when I bought it has no issues hitting 18psi at WOT in any gear and felt super strong up till redline. Now when I begin to roll on the throttle from idle up to around 3k car feels ok then begins to violently shudder until I lift off. Car drives fine driving conservativly around town. Issue has been happening for a while now. No check engine light or codes have ever came up.
The shuddering is very easy to replicate. I am confused as the rail pressure and lpfp psi looks to be within spec with minimal timing corrections, however like I said I'm new to this platform so any advice is appreciated. Log is attached below however I cant go full WOT as once the shuddering begins the car will not increase in rpm.

Car has the following

-mhd as mentioned
-1.75" vrsf silicone inlets
-vrsf dci
-tial BOV with vrsf charge pipe
-PR coils
-1 step colder NGK Iridium plugs gapped to 0.027"(less than 5000 KMs)
-vrsf 7.5" intercooler
-vrsf carless downpipes
-replaced three injectors with brand new index 9s, the rest are two older index 9s and one index 6.
Upgraded RB pcv
Walnut blast a few days ago.

https://datazap.me/u/angus54/lean-afr?log=0&data=3-21

Thanks legends 👍

[jzx_andy]

Got any previous WOT logs from ~2500rpm onwards?

How did you manage to pick up brand new index 9s? Those were discontinued about 9 years ago from memory and there's plenty of brand new fake n54 injectors for sale on ebay/aliexpress these days.

Your log shows its leaning out and short term fuel trims maxed out by about 3000rpm and under partial throttle. Obvious things first - don't boot on it till its sorted out.

You say you're running a 98 ron map but your log filename says its the mhd v9.0 95ron map. Have you tried it with 98ron fuel and a 98ron MHD stage 2+ OTS map?

Things i would do:

1: fill up with 98 and flash car to a 98ron map
2: inspect coil boots and plugs, replace if necessary and apply dielectric grease if you haven't done this before
3: gap current or new plugs down to 0.020"
4: ensure your injector values coding on your dme match those with each individual injector from cyl 1 - > 6
5: troubleshoot o2 sensor values in inpa

[as473]

Originally Posted by jzx_andy

Got any previous WOT logs from ~2500rpm onwards?

How did you manage to pick up brand new index 9s? Those were discontinued about 9 years ago from memory and there's plenty of brand new fake n54 injectors for sale on ebay/aliexpress these days.

Your log shows its leaning out and short term fuel trims maxed out by about 3000rpm and under partial throttle. Obvious things first - don't boot on it till its sorted out.

You say you're running a 98 ron map but your log filename says its the mhd v9.0 95ron map. Have you tried it with 98ron fuel and a 98ron MHD stage 2+ OTS map?

Things i would do:

1: fill up with 98 and flash car to a 98ron map
2: inspect coil boots and plugs, replace if necessary and apply dielectric grease if you haven't done this before
3: gap current or new plugs down to 0.020"
4: ensure your injector values coding on your dme match those with each individual injector from cyl 1 - > 6
5: troubleshoot o2 sensor values in inpa

Hey mate, thanks for the reply. The injectors were new to me. I purchased them from a guy who bought them years ago and never put them in. They seem legit as they came in factory packaging with the metal cap still installed over the Teflon seal. They also came with an invoice from bmw(again a few years old).

To answer your other questions. I do have another log from when I first purchased the car, at the time I was unsure of the whole logging process so it's not ideal as i don't go fully WOT however it still shows more boost without the lean condition I am experiencing now. Plugs at the time were bosh ones gapped to 0.026". I will post below. I was on a 98 oct map with plugs gapped to 0.022" however under hard accel the car threw come superknocking codes. I assumed the plug gap was too small for the PR coils voltage so I gapped up to 0.027" and the superknocking codes have not returned.

I have inspected the coils multiple times and the boot appears to be fine. I have recently put dielectric grease on the plugs too and this did not make any difference. Is it common for PR coils to fail with such little load on them?

I have checked the injector values previously however I will recheck them today. I had a quick look last night and I know that 1-3 is right however I couldn't read the values from 4-6 with the cowl on. I dont have INPA as I couldn't get my laptop to get the black dots on in showing a successful connection however i do have protool working on my phone. Is there any way to check the o2 sensors using protool? Is there anything I should be looking for specifically such as discrepancies between pre and post cat o2?
The afr values at idle on MHD live gauges look to be within spec of each other however like I said I'm new to n54 so not totally sure.

Thanks for the reply i appreciate it


https://datazap.me/u/angus54/log-162...og=0&data=3-22


EDIT: Forgot to mention just purchased a full set of new index 12's. Should be here within a week. Hopefully it will help?

[jzx_andy]

Originally Posted by as473

Hey mate, thanks for the reply. The injectors were new to me. I purchased them from a guy who bought them years ago and never put them in. They seem legit as they came in factory packaging with the metal cap still installed over the Teflon seal. They also came with an invoice from bmw(again a few years old).

To answer your other questions. I do have another log from when I first purchased the car, at the time I was unsure of the whole logging process so it's not ideal as i don't go fully WOT however it still shows more boost without the lean condition I am experiencing now. Plugs at the time were bosh ones gapped to 0.026". I will post below. I was on a 98 oct map with plugs gapped to 0.022" however under hard accel the car threw come superknocking codes. I assumed the plug gap was too small for the PR coils voltage so I gapped up to 0.027" and the superknocking codes have not returned.

I have inspected the coils multiple times and the boot appears to be fine. I have recently put dielectric grease on the plugs too and this did not make any difference. Is it common for PR coils to fail with such little load on them?

I have checked the injector values previously however I will recheck them today. I had a quick look last night and I know that 1-3 is right however I couldn't read the values from 4-6 with the cowl on. I dont have INPA as I couldn't get my laptop to get the black dots on in showing a successful connection however i do have protool working on my phone. Is there any way to check the o2 sensors using protool? Is there anything I should be looking for specifically such as discrepancies between pre and post cat o2?
The afr values at idle on MHD live gauges look to be within spec of each other however like I said I'm new to n54 so not totally sure.

Thanks for the reply i appreciate it


https://datazap.me/u/angus54/log-162...og=0&data=3-22


EDIT: Forgot to mention just purchased a full set of new index 12's. Should be here within a week. Hopefully it will help?

No worries man. So are you running a 98ron map now? If not, it might be worth switching back to it, just to rule out your tune as being a possible culprit.

New index 12s may hopefully sort it out, you can definitely code them in with Protool. Worth getting the cowl off and making sure the injectors coding is all right, just in case.

I'm not too sure about whether you can diagnose o2's with Protool though. From memory there are guides on youtube on diagnosing n54 primary o2 sensor issues with software, what to look out for both afr and voltage wise. In most cases you'll get a fault code when an o2 is on the way out though.

PR coils shouldn't be giving out so easily. Most people with NGK plugs run a spark plug gap closer to 0.020" on N54's. I'm not sure if you can even gap Bosch plugs that are meant for N54's, as they have a 3 prong design afaik. Have you ticked the checkbox for PR coils in MHD?

If you have oem coils laying around which were good, might be worth putting them back on and seeing what happens.

Do you have any other issues with the car? Any errors or faults on the dash cluster or idrive screen?

[as473]

Originally Posted by jzx_andy

No worries man. So are you running a 98ron map now? If not, it might be worth switching back to it, just to rule out your tune as being a possible culprit.

New index 12s may hopefully sort it out, you can definitely code them in with Protool. Worth getting the cowl off and making sure the injectors coding is all right, just in case.

I'm not too sure about whether you can diagnose o2's with Protool though. From memory there are guides on youtube on diagnosing n54 primary o2 sensor issues with software, what to look out for both afr and voltage wise. In most cases you'll get a fault code when an o2 is on the way out though.

PR coils shouldn't be giving out so easily. Most people with NGK plugs run a spark plug gap closer to 0.020" on N54's. I'm not sure if you can even gap Bosch plugs that are meant for N54's, as they have a 3 prong design afaik. Have you ticked the checkbox for PR coils in MHD?

If you have oem coils laying around which were good, might be worth putting them back on and seeing what happens.

Do you have any other issues with the car? Any errors or faults on the dash cluster or idrive screen?

Hey mate, thanks for the reply.

I was under the same impression regarding the 0.020" gap for the NGK plugs however I'm sure this is for stock coils. Not pr as the pr ones have higher voltage and thus can bridge a larger gap. I spoke to a very reputable shop in Sydney and he also suggested running a gap of 0.027" for pr coils on NGK plugs on stg2+. I have a spare set of plugs though that I will put in when the Injectors arrive just to rule them out.

Today I flashed back to stage 0 and the lean condition(afr between 18-21 at points under 90 percent throttle) still remains so I'm thinking it's not the tune. As soon as I start to floor it trims shoot to 34 on both banks and afr starts to lean out however rail pressure is never below 2200psi and lpfp stays above 65psi. Also minimal timing corrections.

The boshe plugs the car came with were not the three pronged ones your talking about so idk what or were the previous owner got them from. And yes I did make sure I ticked the pr coil box on MHD.

I don't have any stock coils unfortunately as I purchased the car with the pr coils installed already however the car was running perfectly when I first got it so I don't think all 6 coils have gone bad in less than 5000 KMs.

Other than that the car has no issues what so ever. No idrive faults, no check engine lights, no codes on MHD active or shadow. Which is why I'm so perplexed by this very frustrating issue. If it was a gap issue or coil issue or O2 sensor going bad wouldn't the car throw at least some kind of fault?

Honestly don't know what else it could be. Vacuum leak? Bad map sensor? Boost solenoids? Vanos?

Thanks for the continued input mate

[Hoper]

Originally Posted by as473

Hey mate, thanks for the reply.

I was under the same impression regarding the 0.020" gap for the NGK plugs however I'm sure this is for stock coils. Not pr as the pr ones have higher voltage and thus can bridge a larger gap. I spoke to a very reputable shop in Sydney and he also suggested running a gap of 0.027" for pr coils on NGK plugs on stg2+. I have a spare set of plugs though that I will put in when the Injectors arrive just to rule them out.

Today I flashed back to stage 0 and the lean condition(afr between 18-21 at points under 90 percent throttle) still remains so I'm thinking it's not the tune. As soon as I start to floor it trims shoot to 34 on both banks and afr starts to lean out however rail pressure is never below 2200psi and lpfp stays above 65psi. Also minimal timing corrections.

The boshe plugs the car came with were not the three pronged ones your talking about so idk what or were the previous owner got them from. And yes I did make sure I ticked the pr coil box on MHD.

I don't have any stock coils unfortunately as I purchased the car with the pr coils installed already however the car was running perfectly when I first got it so I don't think all 6 coils have gone bad in less than 5000 KMs.

Other than that the car has no issues what so ever. No idrive faults, no check engine lights, no codes on MHD active or shadow. Which is why I'm so perplexed by this very frustrating issue. If it was a gap issue or coil issue or O2 sensor going bad wouldn't the car throw at least some kind of fault?

Honestly don't know what else it could be. Vacuum leak? Bad map sensor? Boost solenoids? Vanos?

Thanks for the continued input mate

Careful with the 98 vs 95 Maps guys, my understanding is that the 98 fuel in Aus is 98 Octane but only 95RON so running premium 98 fuel in Aus we should be using 95 RON maps if they're the off the shelf MHD maps

I'd also be chasing the injectors first, if your rail pressure is above 2k and the car is leaning out it's either the tune as Andy says, or the injectors, bit I can't see how the off the shelf MHD tune can be that far out, plenty of people are running it

your thoughts on the O2 sensors are also valid, might also be an issue there as that's how the ECU is determining how rich/Lena the car is, does it smell of fuel? if the O2 sensors are bad and it only thinks it's lean it should smell a bit I would think

[Socket]

Originally Posted by Hoper

Careful with the 98 vs 95 Maps guys, my understanding is that the 98 fuel in Aus is 98 Octane but only 95RON so running premium 98 fuel in Aus we should be using 95 RON maps if they're the off the shelf MHD maps

I'd also be chasing the injectors first, if your rail pressure is above 2k and the car is leaning out it's either the tune as Andy says, or the injectors, bit I can't see how the off the shelf MHD tune can be that far out, plenty of people are running it

your thoughts on the O2 sensors are also valid, might also be an issue there as that's how the ECU is determining how rich/Lena the car is, does it smell of fuel? if the O2 sensors are bad and it only thinks it's lean it should smell a bit I would think

Hey Hops
I agree O2 sensors would be my bet

[as473]

Hey guys, thanks for the reply.

Put a full set of new index 12's in today and it made no difference what so ever. As you can see by the log still very concerning.

Do you guys think I should replace all 4 o2 sensors or just the pre cat ones? Would both o2's go bad like this at the same time? Could it be anything else?
Car does not smell of fuel, it is catless so always has a bit of a smell when stationary but not like fresh fuel, and not when moving.

Thanks for the help

https://datazap.me/u/angus54/post-in...og=0&data=3-21

[Hoper]

Originally Posted by as473

Hey guys, thanks for the reply.

Put a full set of new index 12's in today and it made no difference what so ever. As you can see by the log still very concerning.

Do you guys think I should replace all 4 o2 sensors or just the pre cat ones? Would both o2's go bad like this at the same time? Could it be anything else?
Car does not smell of fuel, it is catless so always has a bit of a smell when stationary but not like fresh fuel, and not when moving.

Thanks for the help

https://datazap.me/u/angus54/post-in...og=0&data=3-21

maybe Vince (aka VTL aka Yoda) can chime in here

Inexpect that the pre-cat O2 sensors do the bulk of the heavy lifting for working out mixture, but I don't actually know for sure

I'd definitely start with pre cat sensors, depends on your funds availability and time availability, if you have funds and the time matters more, just do the lot, if you don't have funds but have time to spare just do the pre cat

all of the above is subject to advice from someone who knows more about what the different sensors do of course, because I'm just using common sense at the moment and that doesn't always work out to be correct

EDIT 1
so I did some searching and reading and found this article, seems.to suggest that both pre and post cat sensors can adjust fuel trim and that the post cat sensors can in fact override the front sensors

https://us.autologic.com/news/fuel-t...-faults-part-2

based on that I reckon I'd change all 4, if this doesn't fix it I'd say you're looking at a DME issue, but weird it's not throwing codes if that's the case

EDIT 2
Thinking about it some more, have you chased vacuum leaks and also exhaust leaks yet? could be screwing with mixtures...

[Socket]

Originally Posted by Hoper

maybe Vince (aka VTL aka Yoda) can chime in here

Inexpect that the pre-cat O2 sensors do the bulk of the heavy lifting for working out mixture, but I don't actually know for sure

I'd definitely start with pre cat sensors, depends on your funds availability and time availability, if you have funds and the time matters more, just do the lot, if you don't have funds but have time to spare just do the pre cat

all of the above is subject to advice from someone who knows more about what the different sensors do of course, because I'm just using common sense at the moment and that doesn't always work out to be correct

EDIT 1
so I did some searching and reading and found this article, seems.to suggest that both pre and post cat sensors can adjust fuel trim and that the post cat sensors can in fact override the front sensors

https://us.autologic.com/news/fuel-t...-faults-part-2

based on that I reckon I'd change all 4, if this doesn't fix it I'd say you're looking at a DME issue, but weird it's not throwing codes if that's the case

EDIT 2
Thinking about it some more, have you chased vacuum leaks and also exhaust leaks yet? could be screwing with mixtures...

post cats basically provide a reference point and the precats do the fine measurement (or something along those lines) Try replacing the two precat 02 sensors first. They are the ones that go bad most of the time

[as473]

Thanks again for the reply guys. So after putting in new pre cat o2 sensors, new 3.5 ar n20 map sensor and double-checking with protools no other error codes were there outside of what mhd can pickup, the issues still remained(if not worse) with afr getting well above 23. At this point, I was honestly so over it all and was seriously considering trying to sell the car for a huge loss as it was doing my head in. Car was still shuddering, still throwing zero codes and was still feeling hesitant under throttle.

As I was sitting in my car contemplating the future of the bmer, I was sitting on the mhd adaptations page. I reset all of the adaptations that are available such as knock sense, lamba, vanos ect as a "it cant be any worse" kinda fix. After this, I locked the car and had some dinner. After this, I jumped in the car and went for a short drive to a servo to fillup. After the fillup I took a WOT log which to my utter bemusement, had afr between 13-14 under wot(stage 0 tune). Now actually screaming with happiness I pulled over and flashed the lowest octane stage 2+ tune, which yielded similar results. Since then the car has been pulling very strong and has no more shuddering, no more super lean conditions, and stangly way less wastegate rattle. I honestly cannot imagine or belive what caused this to happen, why the dme threw no error codes, and why the **** i didn't think to do this weeks ago before shelling out over 3k in parts to rectify this extremly concerning and frustrating issue.

I have attatched a log belong from yesterday with a higher octane stage 2+ flash. Logs obvs look better however is overboosting a bit and has a few timing corrections. Interested to see if you guys think the logs looks ok and if it shows the car has any damage done to it whilst running these extremly lean conditions. Again thankyou all for the input as this is what ultimatly kept me going with the car and has resulted in me fixing the issue and hopfully keeping the mightly n54 for years to come. I genuinly hope noone else has to go through this however if they do maybe this will help(not that i have ever heard or seen this issue before).

Thanks again guys, your bloody legends

https://datazap.me/u/angus54/after-r...=0&data=2-3-21

EDIT: Also noticed that throttle goes from 80 to 40 then back to 80, is this normal, if not could it be because of overboosting. I do have 1.75 inch vrsf inlets, could this cause the overboosting issues?

[jzx_andy]

This is great news. 20/20 hindsight on resetting adaptations lol.

Throttle closures look to be caused by boost momentarily exceeding boost targets in this log. This might also explain the timing corrections. Your log is a pretty short pull, so I wouldn't be too concerned about it.

In isolation, timing corrections may be caused by plugs are gapped just a tad too open. My experience with PR coils is that you actually can't gap the 2 step colder 97506 NGK's much more than 0.020". Your logs may improve with a smaller gap, but I'd take a better log now that things seem to be not so serious anymore.

Have you done much WOT driving on it outside of logging? How does the car feel/perform?

If you want to take a proper log, start in 3rd around 2500rpm, go WOT until you're at the top of 4th gear.

[eastsidaz]

Originally Posted by as473

Thanks again for the reply guys. So after putting in new pre cat o2 sensors, new 3.5 ar n20 map sensor and double-checking with protools no other error codes were there outside of what mhd can pickup, the issues still remained(if not worse) with afr getting well above 23. At this point, I was honestly so over it all and was seriously considering trying to sell the car for a huge loss as it was doing my head in. Car was still shuddering, still throwing zero codes and was still feeling hesitant under throttle.

As I was sitting in my car contemplating the future of the bmer, I was sitting on the mhd adaptations page. I reset all of the adaptations that are available such as knock sense, lamba, vanos ect as a "it cant be any worse" kinda fix. After this, I locked the car and had some dinner. After this, I jumped in the car and went for a short drive to a servo to fillup. After the fillup I took a WOT log which to my utter bemusement, had afr between 13-14 under wot(stage 0 tune). Now actually screaming with happiness I pulled over and flashed the lowest octane stage 2+ tune, which yielded similar results. Since then the car has been pulling very strong and has no more shuddering, no more super lean conditions, and stangly way less wastegate rattle. I honestly cannot imagine or belive what caused this to happen, why the dme threw no error codes, and why the **** i didn't think to do this weeks ago before shelling out over 3k in parts to rectify this extremly concerning and frustrating issue.

I have attatched a log belong from yesterday with a higher octane stage 2+ flash. Logs obvs look better however is overboosting a bit and has a few timing corrections. Interested to see if you guys think the logs looks ok and if it shows the car has any damage done to it whilst running these extremly lean conditions. Again thankyou all for the input as this is what ultimatly kept me going with the car and has resulted in me fixing the issue and hopfully keeping the mightly n54 for years to come. I genuinly hope noone else has to go through this however if they do maybe this will help(not that i have ever heard or seen this issue before).

Thanks again guys, your bloody legends

https://datazap.me/u/angus54/after-r...=0&data=2-3-21

EDIT: Also noticed that throttle goes from 80 to 40 then back to 80, is this normal, if not could it be because of overboosting. I do have 1.75 inch vrsf inlets, could this cause the overboosting issues?

Boost on v9 always seems to over shot target nothing unusual. Fuelling looks good, apart from those timing corrections as you said. Dial it back to the correct 93oct/98ron map. 102ron map is too aggressive.

And as jzx said when you can get a proper log in. All seems ok though

[Socket]

Car crapped itself when you said you might sell it.... hope it behaves itself now it is on notice lol

[as473]

I'll dial it back to 98ron and do a pull as you guys suggested. Car feels very strong in the pull now(holy **** I have missed it). I have only done a bit of hard driving since but seems to rev out very smoothly and with no hesitation. Only was trying the 102ron map as I have a couple of litres of e85 in the tank(Maybe not enough?). Glad to hear you guys think everything is ok. Was very worried all the running lean had caused anything from minor issues to melted pistons. Am going to do a comp test and have a look with my boroscope to double check. Also will do a pull as suggested above next time I get the chance.

I still cannot believe it was the adaptations all along. When I first got the car it had some strange plugs in it, bosche plugs but not the three pronged ones. Also filled up with 98 from 7/11 and had a super knocking code come up. Maybe the DME had some kind of strange knock adaptation causing the afr issue? Really don't know.

I have been very clear with the car that is to be on its best behaviour at all times and even the most minor bout of acting out will cause me to list it on car sales instantly with no remorse or regret. Hopfully it stays in line as we all know that's what n54s are good at :/

Thanks again for the advice guys I appreciate every post. Will update you all with a new log on the 98 map when I get the chance to do some driving in Mexico.

[Hoper]

Originally Posted by as473

I'll dial it back to 98ron and do a pull as you guys suggested. Car feels very strong in the pull now(holy **** I have missed it). I have only done a bit of hard driving since but seems to rev out very smoothly and with no hesitation. Only was trying the 102ron map as I have a couple of litres of e85 in the tank(Maybe not enough?). Glad to hear you guys think everything is ok. Was very worried all the running lean had caused anything from minor issues to melted pistons. Am going to do a comp test and have a look with my boroscope to double check. Also will do a pull as suggested above next time I get the chance.

I still cannot believe it was the adaptations all along. When I first got the car it had some strange plugs in it, bosche plugs but not the three pronged ones. Also filled up with 98 from 7/11 and had a super knocking code come up. Maybe the DME had some kind of strange knock adaptation causing the afr issue? Really don't know.

I have been very clear with the car that is to be on its best behaviour at all times and even the most minor bout of acting out will cause me to list it on car sales instantly with no remorse or regret. Hopfully it stays in line as we all know that's what n54s are good at :/

Thanks again for the advice guys I appreciate every post. Will update you all with a new log on the 98 map when I get the chance to do some driving in Mexico.

Nice one, didn't think of resetting adaptations, they usually won't idle or drive properly either