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Author Topic: Single turbo 2.7T running on 7.1.1 (R ECU) question about mono lambda situation  (Read 15621 times)
Snow Trooper
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Please tell me what I have posted that is false in regards to the single bank issue.
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NOTORIOUS VR
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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.

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?
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Snow Trooper
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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.
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marcellus
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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?

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.
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prj
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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?
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.
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marcellus
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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?
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NOTORIOUS VR
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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.

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.

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

I assume by adjusting the tables that the hack addresses.
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prj
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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.
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phila_dot
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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.
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prj
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I agree, it is indeed very good for a single lambda system.
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NOTORIOUS VR
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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!
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