NefMoto

I don't know if my mine is playing tricks on me or not, but I remember when Snow Trooper was tuning this single turbo there was some issue with having both primary O2's in the same downpipe because the ECU is looking for differences between the banks since the ECU is configured for stereo lambda.

Of course on a single turbo car this is an issue, so I believe back then Snow Trooper got around this by feeding one bank a slightly modified signal from his WB narrowband output to one of the banks O2 sensor inputs.

But for some reason I want to say that I've stumbled upon someone else running a single setup on here that has this problem resolved and running mono lambda? 

The search on this forum kinda blows and haven't been able to come up with anything other then Snow Troopers original fix (here: http://nefariousmotorsports.com/forum/index.php/topic,722.msg6469.html#msg6469 )

Any thoughts on this would be appreciated!

The ECU never looks at any difference between banks.

Yes it does, if they are the same it tries to separate them by trimming one more lean and the other more rich until its happy.  With both sensors in one pipe or a split signal from one it will trim until one is -25% and the other is +25%

Phila_dot created a hack to feed trims from one sensor that works perfect, but if your fuel rail doesn't get evenly fed from both banks it can be iffy because the second bank fed will be lean.

My professional suggestion for the safest setup is to run both factory sensors pre turbo so trims stay accurate.

That is not what Snow Trooper found... did you read that thread (specifically the OP)?

Either way it seems like phila_dot has come up with a working solution that ignores the 2nd O2 sensor completely now.

More info here: http://nefariousmotorsports.com/forum/index.php?topic=2112.180

My buddy who's car I am doing this on thought about doing this, I was just cautious about O2 life considering the high EGT's pre-turbine.

pic of the setup in an 03 A6 avant, went back to the stock IM for now since the TB was too far forward with the custom SMIM:

(https://lh4.googleusercontent.com/-fah4newOHaw/URpvATAkzfI/AAAAAAAAInU/x9yvnJscnK4/s960/20130212_011609.jpg)

No it does not. This is not why this happens.
It never compares the banks, it never compares the trims to the banks and it never tries to separate anything.

The thread where the hack was developed contains information on why this happens. Perhaps you should re-read it.

The life of the sensor will be shortened depending on what kind of egts you see.  A bit of a trade off but in the end the sensors aren't that expensive.  So far nothing else works as reliable or safe.

The only thing he found is the symptom (banks going 25% in opposite direction). His explanation is wrong.
Repeating it won't make it true.

Perhaps you should stfu, I'm not in the mood for your snarky bullshit today.  Post up factual evidence or stop talking.  I have read the thread.  I understand what happens.  Fact is they trim away from each other if they get the same signal or one that is basically the same.

How many single turbo or single downpipe path me7.1 2.7t cars have you seen let alone touched?

I will continue calling you on stuff that you pass on for fact, which you are wrong about.
I did post why this happens. If you do not have the mental capability to understand it, I am sorry for you.

If you take any two feedback loops which go through an amplitude and expect a separate feedback signal for each loop, then merge the signals together and feed it back to both adjusters, then eventually one will max out at + and the other will max out at -.
You don't need ME7, you don't need an engine or lambdas to understand this. It is the basics of how feedback loops work.

You keep saying the ECU compares the banks. At no point does it ever do this, which is why the FR does not state that it does either, and why you can not support what you say with the FR.

^^ Interesting... although I am not in any way familiar with feedback loops, etc...

Do you have a solution for this?

What are the thoughts about running the O2's pre-turbine in the up-pipes in regards to EGT's effecting longevity of the sensors?

I would also really appreciate if you and Snow Trooper could refrain from getting at each others throats, that helps nothing.  I know it's hard sometimes when not all of the angles have been covered and not everything is easily explained.

I agree. the sniping isn't productive.

I'm not a computer wizard like you obviously are so feel awesome.  I have always stated I barely am capable of what I do in a computer sense.  I do however understand engines on a better level than many, or so I have been told.  My theories, hypothesized instructions based of testing facts are only posted as facts when that's how I understand them after REAL WORLD results.  Only share what I know.

You and I have the same end conclusion and answer, they trim away and are different.  Thanks for being a pita.

The solution is already posted by phila_dot.

The fix is to force bank 1 trims on bank 2 and copy over the lambda voltages from bank 1 to bank 2.
That way it won't try to use a separate trim for bank 2.

Basically you can't trim both banks separately when you only have 1 signal which is both banks merged together.
So you have to trim them both by the same amount.

Look at sy_stervk and sy_stersy in the FR to see how it is handled from factory.
In particular, on our cars sy_stersy is false, but you want to set it to true. Of course it is a compile time constant so code has to be modified.

Unlike you, if I am not sure about something I don't open my mouth. There is a distinct line between remarking observations and making up explanations, trying to pass them off as fact and then trying to pull "authority" when they are questioned. The former is helpful, the latter not so much, and you seem to cross this line without hesitation.

Please tell me what I have posted that is false in regards to the single bank issue.

Thanks, I've been reading the dialing in the single thread and it seems that there is a solution that phila_dot made for the S4, but I still do have some concerns about the fueling issue between the banks that Snow Trooper has brought up later in the thread.

At this point, is the "hack" a better solution or is it just worth it to leave the ECU as it was designed/compiled and go with pre-turbine O2's in their specified banks?

Thanks for yet another edit PRJ.

I apologize for my explanations that are so over simplified to you.

I cannot look at assembly info, or rather I do not know how.

In the future to avoid your shit attitude towards me I will not speak of my factual real world results that I obtain from testing variables on my shop car and will not give my opinions on what and why things happen.  I hope others do the same for fear of offending your superior access to information.

Tell you what, start writing up a document with all this amazing info you have and know so we too can have at it and not bore you with our pathetic, cave man level issues and resolutions.

The hack simplifies the setup since now you are able to run one sensor post turbo.  I begged and begged for the hack mostly because I didnt want to add in the two sensors pre-turbo due to the shortened life span.  I think either way will work just fine. 

Even with a slight voltage offset, my trims went crazy.  That was with the LC-1 feeding both banks inputs.

Either you run both sensors pre turbo, or one post turbo with the hack.  One sensor post turbo without the hack, and your trims will be retarded.  Your overall AFR can be spot on, but the ECU will almost always trim the two banks opposite directions, usually ending up in really shitty part throttle/cruise.  Like stated before, the trims eventually will go +25, -25.  At WOT I dont really know.  I was under the impression that at WOT the trims were ignored, but later it was said that they are also used at WOT.  Not sure, but even more reason for the hack for me. 


I can only speak on my car, and what has worked for me thus far.  The hack has helped me a ton, and I can never thank the guys that put in the work for me enough.  I have been running the hack for a while now, and it has been nothing short of amazing for me.

I think that pre-turbo the lambdas will fail all the time as they are not made to tolerate those temps.
The hack that phila_dot made basically alters the way the ECU works in some points as if sy_stersy was set to true.

I don't see anything wrong with it, you just have 1 lambda for 6 cylinders as opposed to 1 lambda per 3 cylinders...
You have to take care and make sure that you don't have fueling issues between the banks and so on, but it's better to do that off of knock feedback.

Advance timing so you have timing pull and compare timing pull between two banks, then richen up the bank that knocks more.

WAIT!  How do you change the fueling on just one bank?

Thanks for the insight, that sounds like a plan to me.  And I agree about the lambda probes pre-turbo which is why I didn't want to do that in the first place.


I assume by adjusting the tables that the hack addresses.

You can adjust per-cylinder using FZN0...5 and FZNWN0...5, but this is based solely on nmot.
Alternatively you can adjust per bank using KFBS, which is based on nmot and rl.

It should be said that KFBS offsets the banks from each other, so whatever is added to one bank is subracted from the other. This might actually be good in this case to offset the combined fuel trim.

I agree, it is indeed very good for a single lambda system.

I was wondering if someone could confirm the locations in a 4Z7907551R (me 7.1.1) box for this hack? 

Not sure if anyone is working on it.  Or even if there is another 7.1.1 image that I would be able to use that someone has been working on and knows the locations I would be willing to move my work over to that I suppose.

Cheers!