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Snow Trooper
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« Reply #345 on: January 26, 2013, 12:42:51 PM »
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I'm with the confused and looking to learn party. So your post says that it is a new issue that crops up because of the 'single input' hack. I thought, by definition, that in open loop (WOT) there is no input. If this is the case, than the issue would be there independent of whether it's a big power single or twin turbo, no? Because the inputs at WOT would be the same, 0 inputs. Or does the stock ECU learn bank specific trims at closed loop operation that it extrapolates into WOT open loop, bank specific usage as well? It does seem that there is bank specific, fuel rail configuration specific calculation/compensation that the stock setup is utilizing, as this guy replaces the crossover with a bigger line and has bank specific issues because of it: http://www.audizine.com/forum/showthread.php/513394-PSA-Don-t-blow-your-motor-because-of-my-stupidity?highlight=fuel+railThe system still applies the LTFTs, even in stock form the s4 in particular will trim each bank a little different due to this issue and it is no big deal. When remove the ability for it to trim each bank independently this happens. Those of us who were using emulation never realized this because stuff was still floating around. We were still feeding different inputs and having the banks get different trim levels. In our quest to stop that floating around this is what we have gotten. |
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cartoons?
6A 61 72 65 64 40 76 6C 6D 73 70 65 63
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britishturbo
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« Reply #346 on: January 26, 2013, 01:36:30 PM »
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You mean the rails with threaded in AN flares that taper down to approx -6 size at the fitting that expand to -8 hose ID and then contract again at the next fitting? Yeah you will have the problem also, it isnt a theory.
You LTFT is based off an average of one rich and one lean bank at this point. Hardly optimal.
The line from the last fuel rail to the FPR is -6 AN anyway... As for the LTFT being an average... indeed it's an average... I could have one at -3% and the other at -1%... at idle and light load, hardly relevant when my WOT "average" from the wideband was used to dial everything in under WOT... I also tune a little richer than most on street tunes on purpose... to make sure there is a little extra fuel always in case of any variations that may occur. I think perhaps you should show some logs to back your claims... if you have your sensors setup as you say then it should be very easy to get logs to back up your claims right? "If" you are correct, then data to prove it would help everyone I think... But... when I put my built engine in, I'm planning on installing another LC-1 unit anyway so that I can run one in each back. I do want to do everything I can to make the built engine higher power setup as safe as possible. Perhaps I'll install some pressure transducers n each rail sometime and log them externally to prove it one way or another. |
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marcellus
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« Reply #347 on: January 26, 2013, 01:41:27 PM »
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I run -6 in to the rail, -8 crossover, and -6 after FPR. My rails IE rails are -8, and that's why I went with them over the -6 that 034 had. From what I was told IIRC by IE, was that my setup should be good for way more than what my motor can handle.
What are things that can be done to monitor the system outside of throwing the narrowbands back in the mix? The other V style motors I have dealt with only use those trims at idle and cruise, every since the newer motors started running sequential fuel injection. At WOT or above a certain RPM they all went batch fire.
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marcellus
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« Reply #348 on: January 26, 2013, 01:44:05 PM »
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The line from the last fuel rail to the FPR is -6 AN anyway...
As for the LTFT being an average... indeed it's an average... I could have one at -3% and the other at -1%... at idle and light load, hardly relevant when my WOT "average" from the wideband was used to dial everything in under WOT... I also tune a little richer than most on street tunes on purpose... to make sure there is a little extra fuel always in case of any variations that may occur.
I think perhaps you should show some logs to back your claims... if you have your sensors setup as you say then it should be very easy to get logs to back up your claims right?
"If" you are correct, then data to prove it would help everyone I think...
But... when I put my built engine in, I'm planning on installing another LC-1 unit anyway so that I can run one in each back. I do want to do everything I can to make the built engine higher power setup as safe as possible.
Perhaps I'll install some pressure transducers n each rail sometime and log them externally to prove it one way or another.
Drilling and tapping the rails for pressure sensors would be easy enough. |
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marcellus
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« Reply #349 on: January 26, 2013, 01:52:01 PM »
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The more I think about it, the more I feel the fuel rails are not the real issue. There are people running the stock fuel rails making tons of power and they are smaller than the upgraded stuff, have less capacity, and are pretty much built the same way as we have laid ours out. They feed from one rail, and have the regulator on the other. No matter what, with this hack, if the motor is using the trims all the way through WOT, we are screwed any way it goes.  Kind of a question.... add: I keep thinking about it, the hack makes them trim exactly the same. So I guess I can see why the hardware needs to be top notch. Imma stop now, because the more I rant the more I confuse myself. |
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« Last Edit: January 26, 2013, 01:56:07 PM by marcellus »
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Snow Trooper
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« Reply #350 on: January 26, 2013, 02:08:59 PM »
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Its not a pressure thing, its a volume thing. The regulator will keep both rails consistent in pressure but that is only part of the equation.
The fuel rails are not the issue by themselves, its the combination with the hack.
BT, dude i like you but you need to learn some respect, your quips towards me on this topic show a total arrogance on your part yet you are operating off your guesses. I am a shop and person that builds these things and spends countless hours refining them, I have been building them longer than anyone and I dont have to give advice on what I find through my own R&D that will in turn help everyone else and save other people (even shops that compete with me) trouble and time, but I do. I give it because I care about the cars and the advancement of them. Stop thinking you know a lot about the s4 in general because you dont, you have shown this to me numerous times.
I tried to help you on your MAP issue, remember when Jibby on AZ told you it was wrong? Yeah that was coming from me. Your response "this is how i always do it on my DSM" or whatever you said, yeah well guess what bud, this isnt your dsm.
I posted this as a warning, take it or dont. The fact that you dont understand what is happening here alarms me considering who you are supposed to be. Your thinking that the last line leading to the FPR matters alarms me. The fact that you want to just come out and disagree and then lead other impressionable people to agree with your lack of knowledge alarms me. Take a step back and use your brain on this one. I generally assume that other people are smarter than me, although right now I feel i am talking to a brick wall that doesnt want to accept something.
Tell you what guys, pull your AN fititngs off and look at your fittings going into the rail, what ID are they?
If you want logs on this, go install pre turbo sensors and log it, the issue is very clear. I 100% guarantee that you would see the first bank trimming negatively and the second trimming positively as it should and like yours IS NOT doing due to the hack.
end rant/
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« Last Edit: January 26, 2013, 02:10:34 PM by Snow Trooper »
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cartoons?
6A 61 72 65 64 40 76 6C 6D 73 70 65 63
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britishturbo
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« Reply #351 on: January 26, 2013, 02:16:25 PM »
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Its not a pressure thing, its a volume thing. The regulator will keep both rails consistent in pressure but that is only part of the equation.
The fuel rails are not the issue by themselves, its the combination with the hack.
BT, dude i like you but you need to learn some respect, your quips towards me on this topic show a total arrogance on your part yet you are operating off your guesses. I am a shop and person that builds these things and spends countless hours refining them, I have been building them longer than anyone and I dont have to give advice on what I find through my own R&D that will in turn help everyone else and save other people (even shops that compete with me) trouble and time, but I do. I give it because I care about the cars and the advancement of them. Stop thinking you know a lot about the s4 in general because you dont, you have shown this to me numerous times.
I tried to help you on your MAP issue, remember when Jibby on AZ told you it was wrong? Yeah that was coming from me. Your response "this is how i always do it on my DSM" or whatever you said, yeah well guess what bud, this isnt your dsm.
I posted this as a warning, take it or dont. The fact that you dont understand what is happening here alarms me considering who you are supposed to be. Your thinking that the last line leading to the FPR matters alarms me. The fact that you want to just come out and disagree and then lead other impressionable people to agree with your lack of knowledge alarms me. Take a step back and use your brain on this one. I generally assume that other people are smarter than me, although right now I feel i am talking to a brick wall that doesnt want to accept something.
Tell you what guys, pull your AN fititngs off and look at your fittings going into the rail, what ID are they?
If you want logs on this, go install pre turbo sensors and log it, the issue is very clear. I 100% guarantee that you would see the first bank trimming negatively and the second trimming positively as it should and like yours IS NOT doing due to the hack.
end rant/
I never once didn't respect your experience and if it came over that way I'm sorry. My point was simply that I (and others) must be missing something in what you are saying. The point about logs was also to help everyone understand what you are seeing... As for the map sensor yeah I was wrong on how me would react to that and I said that... I don't remember anyone saying about it until I asked about it on here. |
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jibberjive
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« Reply #352 on: January 26, 2013, 02:35:51 PM »
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Jared, any idea why the guy in the AZ link I posted was having issues with a bigger/different crossover tube (on a stock, twin O2 setup), and why the ECU wasn't just compensating with the trims as it should be with that?
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marcellus
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« Reply #353 on: January 26, 2013, 02:45:41 PM »
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Got it, I think. Although the pressure across the rails could be the same the volume could be different.
Eh, screw it. Still confused, don't care anymore. In my mind there is one setup that should work, and one setup that will work. I will feed both rails. DONE. I don't want to chance it over something so simple.
Thanks for the heads up.
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britishturbo
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« Reply #354 on: January 26, 2013, 02:47:07 PM »
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Jared, any idea why the guy in the AZ link I posted was having issues with a bigger/different crossover tube (on a stock, twin O2 setup), and why the ECU wasn't just compensating with the trims as it should be with that?
Rob (Rtl the guy in that post) went to 034 fuel rails and his problem went away... |
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Snow Trooper
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« Reply #355 on: January 26, 2013, 02:54:02 PM »
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He probably didnt give it enough time or sensors were not spot on. Or maybe he had enough pump that it was really magnified on his setup. I dont know his specifics.
There is almost to be an expected 3-5% difference if you are running a lot of fuel up to the rail (an its a crossover setup, especially stock) and the bi-turbo setups, regardless of fuel rail setup will trim that out easily.
We lose that ability with the hack and a single using a single sensor in the downpipe. You go on non the wiser because the readings at the wideband/narrowband look perfect. Ecu goes on non the wiser because its sensor input looks perfect.
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cartoons?
6A 61 72 65 64 40 76 6C 6D 73 70 65 63
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jibberjive
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« Reply #356 on: January 26, 2013, 05:38:44 PM »
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Rob (Rtl the guy in that post) went to 034 fuel rails and his problem went away...
I know, and the bank-specific-trimming ECU should trim that bad boy out, no? He probably didnt give it enough time or sensors were not spot on. Or maybe he had enough pump that it was really magnified on his setup. I dont know his specifics.
There is almost to be an expected 3-5% difference if you are running a lot of fuel up to the rail (an its a crossover setup, especially stock) and the bi-turbo setups, regardless of fuel rail setup will trim that out easily. Is there a limit to the percentage delta between the two banks? Is it just the same limit as all LTFT's? |
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phila_dot
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« Reply #357 on: January 26, 2013, 08:27:33 PM »
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In the case of open loop, only the the long term trims are active.. so the issue with mono vs stereo is only if having a hacked stereo is causing your trims to look identical when they should look drastically different? This makes no sense, since IIRC there is no load/rpm based long term trim (other than idle/part) If you are running out of fuel in one bank only at high rpm/load, and your part trims would be the same (if you had a proper stereo setup), how would having a stereo setup save you? Not criticizing, just confused  LTFT's are all calculated in different ml, rl, and nmot ranges. |
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phila_dot
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« Reply #358 on: January 26, 2013, 08:28:42 PM »
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I know, and the bank-specific-trimming ECU should trim that bad boy out, no?
Is there a limit to the percentage delta between the two banks? Is it just the same limit as all LTFT's?
Fuel trims are never compared between banks and there is no delta consideration. |
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britishturbo
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« Reply #359 on: January 26, 2013, 08:42:46 PM »
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Just got done doing my first test drive with the VMP HPX 5000 MAF sensor in blow through setup, replacing the stock MAF.
I dialed the boost down to about 15psi to be safe but provisionally it looks like I got everything pretty much spot on the first time :-)
The car did for sure run smoother with the HPX sensor compared to the Hitachi though, especially at idle where the Hitachi would have a random miss here and there.
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