[n55david]

Originally Posted by thejeremyman9

Impossible for the secondary O2? It doesn't directly control fuel trims (that's the job of the wideband, primary O2), but it supposedly is used to prevent drift of primary O2 since secondary O2 is a narrowband and is much more accurate within that small AFR window.

yeah but the secondary numbers would be useless.. here's why

first off the numbers would change as the cat heats up and over time as the cat loses efficiency the numbers would change. second, the numbers would dramatically change with a dp swap. you would need custom calibrations for offsets with different dps etc. plus the narrowband window is so small it's literally only there to make sure there is a specific offset/difference from the primary 02 to know if the cat is working or not.

there just isn't a place for this in the tunes, if there was and this was a thing it would be a nightmare for tuning.

[thejeremyman9]

Originally Posted by Phantom10R

yeah but the secondary numbers would be useless.. here's why

first off the numbers would change as the cat heats up and over time as the cat loses efficiency the numbers would change. second, the numbers would dramatically change with a dp swap. you would need custom calibrations for offsets with different dps etc. plus the narrowband window is so small it's literally only there to make sure there is a specific offset/difference from the primary 02 to know if the cat is working or not.

there just isn't a place for this in the tunes, if there was and this was a thing it would be a nightmare for tuning.

I understand conceptually that the cat is going to affect the readings of the secondary O2 just by nature of the way it operates, and that there are differences due to temp on a given cat, and obviously differences between cats and catted vs catless. Yes the NB window is very small around lambda =1, but that's the point of it being NB lol. I wouldn't say there isn't a place for it in the tunes though...

We don't need to debate about it anymore because absent any "official" documentation for the N55 its just back and forth. I said my 2c based on everything i have seen and my recommendation against running one long term for OP (why this came up in the first place). I found the last thread i posted a few references in so ill drop that link here. Yes, its not N55 F3x, but there's no reason for me to believe something that is applicable on N54 and other modern platforms doesnt apply here... plus there are numerous reputable sources stating exactly what i have. Take it FWIW lol. No hard feelings if you dont believe me /shrug.

https://f30.bimmerpost.com/forums/sh...8&postcount=17

[thejeremyman9]

FYI, i just emailed MHD and this was their response. Vague as it is, they said not to run them... But hey, ya'll can continue to believe whatever you want.

[winther1]

Originally Posted by thejeremyman9

I am confused, when is there ever a danger in running catless and why would there be no danger "on BM3 even on stage 2"? BM3 stage 2 specifically calls for a high-flow (catted or catless DP), so yeah, that is the map that is actually designed to be ran with a non-OEM DP.... Also, it has absolutely nothing to do with being boost-based or load-based. All MHD maps are load based and 2/2+ are designed to be ran with upgraded DP. Your final sentence makes absolutely no sense - the BM3 stage 2 map is specifically designed to be ran with a DP, so it is even more "tuned" for the DP than the stock tune, which will rely on closed loop fueling (and other adaptations) to account for the DP. Not trying to be mean, but lets not spread misinformation.

Do not run an O2 spacer. They are not made to be ran long term and all the information indicates the secondary O2 is used for fuel trim control / primary O2 drift in addition to monitoring cat efficiency. Just tune out the CEL if you dont want it to show up.

Who sold you the wagner?

I'm not too bothered about the CEL light. I just want to make sure the car can pass MOT.
As I understand, coding out CEL will not sort the reason the light is on, and emissions will fail the car

[thejeremyman9]

Originally Posted by winther1

I'm not too bothered about the CEL light. I just want to make sure the car can pass MOT.
As I understand, coding out CEL will not sort the reason the light is on, and emissions will fail the car

Right - the catalyst monitor will not be ready even if you code out the CEL. Whether or not you fail because of that depends on local laws.

[BMWILUVU]

Originally Posted by thejeremyman9

You don't need to explain anything really. Frankly most of your post made no sense at all.

I know you keep arguing in other threads as well that the secondary O2 isnt used for fuel trim control, despite the fact that MHD specifically said so (for our platform/engine) in response to a an email question about using a spacer on the secondary O2 (its buried in the MHD thread), and that it is well documented for the N54 and numerous other car platforms. I never said i am 100% sure based on XYZ from BMW for the F3x N55 that the secondary O2 is used for fuel trims (see my post - "all the information indicates"). I was very careful with my word choice so as to not imply a level of certainty above what i have. Nonetheless, it makes no sense at all to run one long term and take an unnecessary risk based on all the information we have when you can just code out the CEL. I am providing OP with information and he can make his own decision.

You are being a rear-hole. Not sure what your problem is really to say these things so you must have been slighted in some way in some other thread. I post to help fellow owners on the forum not to have some kind of ego sprint with you.
"Supposedly preventing drift" BMW's ISTA explicitly says the secondary O2 is only used for catalyst monitoring. I am not sure how much clearer it has to be.
So are we supposed to believe you and your one e-series youtube video from some misc guy and a one-liner from MHD over BMW ISTA used at dealership repair centers all over the globe?
So you say all information you have indicates but yet when I ask you, you really don't have much beyond this and yet are giving recommendations on your "indications". I think its you who should stop spreading misinformation.

[thejeremyman9]

Originally Posted by BMWILUVU

You are being a rear-hole. Not sure what your problem is really to say these things so you must have been slighted in some way in some other thread. I post to help fellow owners on the forum not to have some kind of ego sprint with you.
"Supposedly preventing drift" BMW's ISTA explicitly says the secondary O2 is only used for catalyst monitoring. I am not sure how much clearer it has to be.
So are we supposed to believe you and your one e-series youtube video from some misc guy and a one-liner from MHD over BMW ISTA used at dealership repair centers all over the globe?
So you say all information you have indicates but yet when I ask you, you really don't have much beyond this and yet are giving recommendations on your "indications". I think its you who should stop spreading misinformation.

Lol, the same thing happens every time this is brought up. You try to spin it like i am the bad guy for contradicting your position that the secondary O2 is only used for catalyst monitoring. It's hilarious that you claim i am posting based on ego rather than helping people on the forums when anyone who reads around the forums knows that i post potentially more than anyone [in the N55 section at least] helping people. Personal attacks don't help your case...

Anyways, I merely recommended the safer/more conservative approach, which was to not run any kind of spacer or anything on the secondary O2 long term. I'm happy to take a look at ISTA information on the secondary O2, specifically if it says it is only used for catalyst monitoring and nothing else (i.e., not that it mentions catalyst monitoring and not fuel trims wherever you are looking). I posted more than just the youtube video... there are numerous threads discussing it, MHD says not to run them, and people report adverse effects from doing so long term... Like i said everyone is free to consider the information presented to them and make their own conclusion as to what they are used for and if they want to run anything on the secondary O2s.

I only posted so that OP was aware of potential issues since he mentioned using a spacer. The last thing i would want is him to use a spacer and inadvertently affect his car thinking it was totally fine to do so. Again - trying to be helping, has nothing to do with ego as you falsely claim.

Someone can go ahead and experiment on their car by running a spacer/minicat and see what happens, or hell just delete the secondary O2 if you are catless since it's not doing anything anyways except telling you your cat is missing

[BMWILUVU]

Originally Posted by thejeremyman9

Lol, the same thing happens every time this is brought up. You try to spin it like i am the bad guy for contradicting your position that the secondary O2 is only used for catalyst monitoring. It's hilarious that you claim i am posting based on ego rather than helping people on the forums when anyone who reads around the forums knows that i post potentially more than anyone [in the N55 section at least] helping people. Personal attacks don't help your case...

Anyways, I merely recommended the safer/more conservative approach, which was to not run any kind of spacer or anything on the secondary O2 long term. I'm happy to take a look at ISTA information on the secondary O2, specifically if it says it is only used for catalyst monitoring and nothing else (i.e., not that it mentions catalyst monitoring and not fuel trims wherever you are looking). I posted more than just the youtube video... there are numerous threads discussing it, MHD says not to run them, and people report adverse effects from doing so long term... Like i said everyone is free to consider the information presented to them and make their own conclusion as to what they are used for and if they want to run anything on the secondary O2s.

I only posted so that OP was aware of potential issues since he mentioned using a spacer. The last thing i would want is him to use a spacer and inadvertently affect his car thinking it was totally fine to do so. Again - trying to be helping, has nothing to do with ego as you falsely claim.

Someone can go ahead and experiment on their car by running a spacer/minicat and see what happens, or hell just delete the secondary O2 if you are catless since it's not doing anything anyways except telling you your cat is missing

No you stated it as fact when its really just your belief. Honestly why should anyone take your advice if you don't even have the judgement to refer to BMW's own technical database. Sounds pretty foolish and illogical to me. So obviously you don't know what you are talking about and then you come online and have an attitude about it. Pretty pathetic. I deal in facts not beliefs. Try it sometime.

[thejeremyman9]

Originally Posted by BMWILUVU

No you stated it as fact when its really just your belief. Honestly why should anyone take your advice if you don't even have the judgement to refer to BMW's own technical database. Sounds pretty foolish and illogical to me. So obviously you don't know what you are talking about and then you come online and have an attitude about it. Pretty pathetic. I deal in facts not beliefs. Try it sometime.

So aggressive and insulting for no reason lol... Classic example of ad hominem fallacy...

Let's have a quick recap - first, i did not "state as fact", i have, over the course of may last several posts, presented information and very explicitly stated my reasoning and that it is not a statement of fact:

Originally Posted by thejeremyman9

Do not run an O2 spacer. They are not made to be ran long term and all the information indicates the secondary O2 is used for fuel trim control / primary O2 drift in addition to monitoring cat efficiency. Just tune out the CEL if you dont want it to show up.

Originally Posted by thejeremyman9

...I never said i am 100% sure based on XYZ from BMW for the F3x N55 that the secondary O2 is used for fuel trims (see my post - "all the information indicates"). I was very careful with my word choice so as to not imply a level of certainty above what i have. Nonetheless, it makes no sense at all to run one long term and take an unnecessary risk based on all the information we have when you can just code out the CEL. I am providing OP with information and he can make his own decision...

Is is actually you that states it as fact... I am happy to learn more (that's why i'm on the forums), so please share the tech docs from BMW for all of our benefit

Let's also have a quick recap of the other things you said (numbers added):

Originally Posted by BMWILUVU

I would be very surprised if a 200 cell DP could avoid a CEL without spacers so getting a CEL witht he Wagner 200 is normal. (1) I would not say there is no danger in running catless on BM3 even on stage 2 since it is boost based. (2) If you are worried, I suggest having an experienced custom tuner adjust your tune.(3) I would feel better running catless on stock than on BM3 but I wouldn't say there is no danger there either.

1 - When/why is there ever a danger in running catless and why would there be no danger "on BM3 even on stage 2"? BM3 stage 2 specifically calls for a high-flow (catted or catless DP), so yeah, that is the map that is actually designed to be ran with a non-OEM DP.... Also, it has absolutely nothing to do with being boost-based or load-based. All MHD maps are load based and 2/2+ are designed to be ran with upgraded DP. The two different tuning strategies have nothing to do with the DP.

2 - Custom tune is not needed for a DP when the OTS maps are specifically designed to be ran with or without DP depending on the "stage"...

3 - Not sure i follow this either... the BM3 stage 2 map is specifically designed to be ran with a DP, so it is even more "tuned" for the DP than the stock tune, which will rely on closed loop fueling (and other adaptations) to account for the DP (since it expects OEM cat in place). Please explain why running catless on stock tune is better than running on a tune made for having a DP? And why there would be a danger in either case?

No personal attacks here, just responding to information. Happy to be informed if you have anything to the contrary.

[BMWILUVU]

Right so BM3 OTS is tuned for every configuration of high flow and catless downpipe right?
Also, what of this drift you keep talking about? Do you have any data and information as to why there would be drift in fuel trims because of the secondary O2?
You make a whole lot of non-sense and dare to come online and start posting your beliefs and insulting people when your ego was bruised because you might be wrong. I've already told you what BMW ISTA said. Take the matter up with BMW. You obviously have no idea what you are talking about.

[thejeremyman9]

Originally Posted by BMWILUVU

(1) Right so BM3 OTS is tuned for every configuration of high flow and catless downpipe right?
(2) Also, what of this drift you keep talking about? Do you have any data and information as to why there would be drift in fuel trims because of the secondary O2?
(3) You make a whole lot of non-sense and dare to come online and start posting your beliefs and insulting people when your ego was bruised because you might be wrong. I've already told you what BMW ISTA said. Take the matter up with BMW. You obviously have no idea what you are talking about.

(1) Yup, that's really the point of the OTS maps that are designed around specific hardware prerequisites. Hell, some people even choose to run certain maps without the hardware (IC/DP/etc) and although not recommended, they still work because the DME is capable of adapting to deviations from what is expected. It's a custom tune that would be optimized for your specific hardware configuration.

(2) Plenty of articles on O2 drift over time. Also its not drift because of the secondary O2. Its using the NB secondary O2 to prevent drift from a primary wideband O2. Suggest googling O2 sensor drift and you will get plenty of informative articles and how the NBO2s are used across numerous platforms to prevent drift from primary O2s.

(3) I really dont understand why you keep saying these things, seeing as how you are the one continuously being aggressive and insulting while i am doing none of that and merely presenting information. Yeah i know what you said and i asked for some references/screenshots/point me to where i can find it so i can see for myself. I have nothing to take up with BMW. You're just throwing insults and being extremely defensive because i am challenging your position

[BMWILUVU]

Originally Posted by thejeremyman9

(1) Yup, that's really the point of the OTS maps that are designed around specific hardware prerequisites. Hell, some people even choose to run certain maps without the hardware (IC/DP/etc) and although not recommended, they still work because the DME is capable of adapting to deviations from what is expected. It's a custom tune that would be optimized for your specific hardware configuration.

(2) Plenty of articles on O2 drift over time. Also its not drift because of the secondary O2. Its using the NB secondary O2 to prevent drift from a primary wideband O2. Suggest googling O2 sensor drift and you will get plenty of informative articles and how the NBO2s are used across numerous platforms to prevent drift from primary O2s.

(3) I really dont understand why you keep saying these things, seeing as how you are the one continuously being aggressive and insulting while i am doing none of that and merely presenting information. Yeah i know what you said and i asked for some references/screenshots/point me to where i can find it so i can see for myself. I have nothing to take up with BMW. You're just throwing insults and being extremely defensive because i am challenging your position

OTS maps were never meant to cover all the configurations people have. Glad you finally realized that.
The only drift is from aging of the primary wideband which is going to happen overtime anyway. This is nothing to do with the spacer on a secondary O2. This type of degradation happens over time in any normal car.
Stop trying to turn this around. I courteously warned you off with several posts when you were being an unreasonable insulting rear-hole now we get to check on all of your BS you've been posting.

[thejeremyman9]

Originally Posted by BMWILUVU

OTS maps were never meant to cover all the configurations people have. Glad you finally realized that.

They cover variations within the bounds of the required/recommended hardware for each stage. So if the tune calls for an IC upgrade, it is designed to work with anything from a 5'' stepped to a full race for example. Same exact concept for DPs, from a higher cell aftermarket to a catless. That's just the way the OTS maps have to be designed to retain this level of flexibility. Of course, they also work with other configurations outside of those, as numerous people have inlets, intakes, TIC, and other mods that are not specifically called for as prerequisites to the tune, but the tunes work great with them nonetheless. I don't know why you think i just realized something? It is your statement about it being better to run catless on stock tune than stage 2 tune that was incorrect. I have been saying the same thing all along lol.

Originally Posted by BMWILUVU

The only drift is from aging of the primary wideband which is going to happen overtime anyway. This is nothing to do with the spacer on a secondary O2. This type of degradation happens over time in any normal car.

Correct, it does happen over time naturally. This is exactly where the secondary O2 sensors come in! Again i suggest you do some google searches to read up on it a bit more. I'll post two more general links here (i.e., not N55 specific, just on this topic since this talks generally about the DME on N20, N54, etc).

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

https://blog.fcpeuro.com/faulty-oxyg...toms-diagnosis
"The signal from the second bank of oxygen sensors is used primarily to detect any problems with the vehicle's catalyst and to tune the fuel trim."

bmw.s*p*o*o*l*s*t*r*e*e*t.com/threads/secondary-o2-sensors-tuned-still-needed.4877/#post-73369
(delete the *'s in the web address)

Originally Posted by BMWILUVU

Stop trying to turn this around. I courteously warned you off with several posts when you were being an unreasonable insulting rear-hole now we get to check on all of your BS you've been posting.

I'm not turning anything around. I keep presenting additional information for everyone's benefit, whereas i don't really see you contributing anything here? Please do point out more of this "BS" i have been posting, happy to be fact-checked and read any additional information you or others may provide on this topic or any other .

[BMWILUVU]

Love how you try to misrepresent everything going on to defend yourself and your crappy attitude. I also emailed FCPEURO about their comments and received no reply. I am well aware of what some of the other manufacturers do and that does not mean BMW does that and it does not mean the latest generation. And I told you in other threads your one holier than thou by some random person youtube video was on on e-series. Your article mentions the N54 engine itself. Do you drive an N54?
Meanwhile, you have created an urban legend around this.

[thejeremyman9]

Originally Posted by BMWILUVU

Love how you try to misrepresent everything going on to defend yourself and your crappy attitude. I also emailed FCPEURO about their comments and received no reply. I am well aware of what some of the other manufacturers do and that does not mean BMW does that and it does not mean the latest generation. And I told you in other threads your one holier than thou by some random person youtube video was on on e-series. Your article mentions the N54 engine itself. Do you drive an N54?
Meanwhile, you have created an urban legend around this.

Originally Posted by BMWILUVU

Love how you try to misrepresent everything going on to defend yourself and your crappy attitude. I also emailed FCPEURO about their comments and received no reply. I am well aware of what some of the other manufacturers do and that does not mean BMW does that and it does not mean the latest generation. And I told you in other threads your one holier than thou by some random person youtube video was on on e-series. Your article mentions the N54 engine itself. Do you drive an N54?
Meanwhile, you have created an urban legend around this.

As I noted above i only posted the non-N55 links to provide general information about the drive/cal discussion. Not intended to be "proof" this is the case on the N55 and noted as such. You keep going back to the YouTube video but that again was just one example with such general information and not intended to discuss the N55 specifically. I didn't create anything, i just presented information and everyone can make their own decision as to what they want to do given the information before them. As i said a couple of posts ago, I would be happy to look at someone's logs before/after they run a spacer on the secondary O2 or even what happens if they unplug/delete them. Based on what you are saying, none of that would matter, right?

Appreciate you finally posting ISTA so we can read it in context. The sentence you underlined says its not used for mixture preparation/control - we know the secondary O2 doesn't do anything for mixture control. As discussed in the paragraphs above in ISTA that's the job of the primary (wideband O2). It's too bad it doesn't say it only serves catalytic converter diagnosis since that would have been your "smoking gun".

I don't have ISTA installed but I'd like to also read what's above and below that screenshot; I'll see what i can find online. Would also love for someone to do this experiment themselves to see what really happens, which should be nothing negative if what you are saying is true Everyone with catless DPs (or most catted) should just be running spacers and minicats to pass emissions lol

[Logicoeur]

Nothing happens by running a high flow catted downpipe on an OE tune. I did it for two months. No issues.


There is nothing to tune for with catted/catless. DME tunes ask for one of the two past stage one just because of the higher EGTs we see from the increased load on the engine. With the OE dp the EGTs would likely end up catastrophic after some time. Remember what the cat is there for. It is simply there to burn off fuel in the exhaust gases. Nothing else. Nothing about that account of excess fuel is necessary for anything in the tune.

[thejeremyman9]

Originally Posted by Logicoeur

Nothing happens by running a high flow catted downpipe on an OE tune. I did it for two months. No issues.


There is nothing to tune for with catted/catless. DME tunes ask for one of the two past stage one just because of the higher EGTs we see from the increased load on the engine. With the OE dp the EGTs would likely end up catastrophic after some time. Remember what the cat is there for. It is simply there to burn off fuel in the exhaust gases. Nothing else. Nothing about that account of excess fuel is necessary for anything in the tune.

Yup, that's why the different stages that "require" certain hardware mods are really just recommendations. Some people run the tunes without the hardware (i.e., no DP or no IC), but they they just don't reap the full benefits of the tune and/or suffer the side effects (like higher EGTs are you mentioned, higher WGDC with no DP is another major factor, or high IATs and poor timing with no IC, etc).

On the flip side there are also people that run bolt ons without any tune, or with a lower stage tune that they technically could run. In that case you are essentially running more hardware than what your tune calls for, essentially the opposite as the other scenario. But again no real concern on this platform given closed loop fueling and load-based engine control. It's really on other cars that don't have the same level of DME control that run into issues with doing boltons with no tune (similar to what OP was being told earlier on in the thread about the DP). But that just doesnt apply here.

[BMWILUVU]

Originally Posted by thejeremyman9

As I noted above i only posted the non-N55 links to provide general information about the drive/cal discussion. Not intended to be "proof" this is the case on the N55 and noted as such. You keep going back to the YouTube video but that again was just one example with such general information and not intended to discuss the N55 specifically. I didn't create anything, i just presented information and everyone can make their own decision as to what they want to do given the information before them. As i said a couple of posts ago, I would be happy to look at someone's logs before/after they run a spacer on the secondary O2 or even what happens if they unplug/delete them. Based on what you are saying, none of that would matter, right?

Appreciate you finally posting ISTA so we can read it in context. The sentence you underlined says its not used for mixture preparation/control - we know the secondary O2 doesn't do anything for mixture control. As discussed in the paragraphs above in ISTA that's the job of the primary (wideband O2). It's too bad it doesn't say it only serves catalytic converter diagnosis since that would have been your "smoking gun".

I don't have ISTA installed but I'd like to also read what's above and below that screenshot; I'll see what i can find online. Would also love for someone to do this experiment themselves to see what really happens, which should be nothing negative if what you are saying is true Everyone with catless DPs (or most catted) should just be running spacers and minicats to pass emissions lol

When something is right in your face and still over your head, its hopeless since you can't seem to get over your own ego reaching for things that just aren't there just so you can be right when BMW says no.

[thejeremyman9]

Originally Posted by BMWILUVU

When something is right in your face and still over your head, its hopeless since you can't seem to get over your own ego reaching for things that just aren't there just so you can be right when BMW says no.

Nothing is hopeless, no ego, and not reaching for anything . Not sure why you keep repeating those things.

The absence of information on any type of calibration/drift control/etc in your screenshot doesn't mean it doesn't exist - you showed just one part of one page in ISTA. How do we know there isnt another page that talks about fuel trims or calibration tables that doesn't say anything else? That one screenshot doesn't erase all the other evidence to the contrary from user-reported effects, tuners advice, etc. Everyone is free to consider the weight of evidence when making the decision as to whether or not they should run anything on the secondary O2. And if anyone does, or decides to delete them entirely, i am happy to look at before/after datalog and whatnot to see what happens. I appreciate you posting the ISTA screenshot for everyone's benefit, we don't need to go in circles anymore unless you find something else to share, and i will do the same if i come across anything