AEM F/IC Setup
Senior Member
SL Member
Joined: Nov 2008
Posts: 680
From: Phoenix, AZ
Im having trouble with my FIC. I had to buy a new one and everytime I go to start the car it wont start without me having to hold the gas down and it backfiring like crazy. I have hex file 104 flash in the fic and a tune my local shop tuned me with. the tune works well under throttle but everytime i come to a stop the rpms would bounce up and down till it finally rested at around 500 rpms then it would stall. only idle and starting the car up are my only problems. with the stock ecu pluged in the car starts right up. can anyone help me out?
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Scionetics
KAD
SL Member
Joined: Oct 2005
Posts: 11,936
From: Western NY
Alright so is it or is it not normal to not be seeing anything on the b1s1 b1s2 o2 readouts on the fic gauges screen it also doesnt datalog any volts its hooked up with a boomslang pnp
ok trims a re gettin there she runnin pretty good however it is a _____ to start takes for ever but when she does she idles great and trim is perfect. also im gettin a catalyst effeciency code is that just cause my trims arent perfect or am i gonna be stuck with that cause the fi does not control rear o2
Thread Starter
Joined: Feb 2008
Posts: 11,271
From: Houston, TX
p0420 is because you no longer have a cat. fix this cell with ye'ol anti-fouler trick (look it up, quit a few threads about it already). you are correct though, the fic does not control the secondary o2 sensor (you could configure the fic to do so but in the end its just easier to hook up an antifouler). hard start issue could be a few things, leaks, plugs, fuel map (cells where you start the car up in), and so forth.
Thread Starter
Joined: Feb 2008
Posts: 11,271
From: Houston, TX
yeppers...fic doesnt show ecu fuel trims...scangaugeII has been the best unit iv used for the price.
what he is seeing is the two boxes when you open up the gauge feature on the fic that is labeled o2, its like aem made the software so that you could view the o2 output voltage but never gave you any input/output leads. instead all you get are taps. if looking at the universal fic harness you only have two o2 leads (bank 1 and bank 2). I pray someday they will turn these leads into input/output with the ability to datalog both voltages. though they would have to add a couple more pins in order to keep it 6cyl friendly (duel primary).
what he is seeing is the two boxes when you open up the gauge feature on the fic that is labeled o2, its like aem made the software so that you could view the o2 output voltage but never gave you any input/output leads. instead all you get are taps. if looking at the universal fic harness you only have two o2 leads (bank 1 and bank 2). I pray someday they will turn these leads into input/output with the ability to datalog both voltages. though they would have to add a couple more pins in order to keep it 6cyl friendly (duel primary).
im used to the apr it lets my control rear o2 but anti fouler is cheap so screw it. Ive already eliminated the easy stuff ie leaks plugs etc but im gonna try richin up the fuel in the start section see what i get thanx for the response
Two questions:
1) Why isn't this thread stickied?
2) Why does almost everyone override their AFR sensor by using the voltage based O2 map? Correct me if I'm wrong but doesn't this negate the purpose of having closed loop AFR feedback and prevent the ECU from adjusting to small AFR changes caused by temp, altitude, etc.? When you place a 3.2 in a cell you're telling the FIC to skew the AFR sensor reading to 3.2v regradless of what the AFR sensor is actually reading. So if the AFR sensor reads 4.0v (17.4:1) the FIC is going to skew the reading so that the ECU sees 3.2v (14.7:1) and does nothing to richen the lean AFR.
Wouldn't it be better to use the percent mode and only modify the AFR sensor signal where needed and letting the ECU handle closed loop AFR tuning in low load? You can still skew the signal anywhere you want to add fuel while allowing the ECU to take care of idle and low rpm tuning. I suspect that overriding the AFR sensor has a lot to do with the idle problems and inability to adjust for temp and altitude changes that so many FIC users experience.
1) Why isn't this thread stickied?
2) Why does almost everyone override their AFR sensor by using the voltage based O2 map? Correct me if I'm wrong but doesn't this negate the purpose of having closed loop AFR feedback and prevent the ECU from adjusting to small AFR changes caused by temp, altitude, etc.? When you place a 3.2 in a cell you're telling the FIC to skew the AFR sensor reading to 3.2v regradless of what the AFR sensor is actually reading. So if the AFR sensor reads 4.0v (17.4:1) the FIC is going to skew the reading so that the ECU sees 3.2v (14.7:1) and does nothing to richen the lean AFR.
Wouldn't it be better to use the percent mode and only modify the AFR sensor signal where needed and letting the ECU handle closed loop AFR tuning in low load? You can still skew the signal anywhere you want to add fuel while allowing the ECU to take care of idle and low rpm tuning. I suspect that overriding the AFR sensor has a lot to do with the idle problems and inability to adjust for temp and altitude changes that so many FIC users experience.
Two questions:
1) Why isn't this thread stickied?
2) Why does almost everyone override their AFR sensor by using the voltage based O2 map? Correct me if I'm wrong but doesn't this negate the purpose of having closed loop AFR feedback and prevent the ECU from adjusting to small AFR changes caused by temp, altitude, etc.? When you place a 3.2 in a cell you're telling the FIC to skew the AFR sensor reading to 3.2v regradless of what the AFR sensor is actually reading. So if the AFR sensor reads 4.0v (17.4:1) the FIC is going to skew the reading so that the ECU sees 3.2v (14.7:1) and does nothing to richen the lean AFR.
Wouldn't it be better to use the percent mode and only modify the AFR sensor signal where needed and letting the ECU handle closed loop AFR tuning in low load? You can still skew the signal anywhere you want to add fuel while allowing the ECU to take care of idle and low rpm tuning. I suspect that overriding the AFR sensor has a lot to do with the idle problems and inability to adjust for temp and altitude changes that so many FIC users experience.
1) Why isn't this thread stickied?
2) Why does almost everyone override their AFR sensor by using the voltage based O2 map? Correct me if I'm wrong but doesn't this negate the purpose of having closed loop AFR feedback and prevent the ECU from adjusting to small AFR changes caused by temp, altitude, etc.? When you place a 3.2 in a cell you're telling the FIC to skew the AFR sensor reading to 3.2v regradless of what the AFR sensor is actually reading. So if the AFR sensor reads 4.0v (17.4:1) the FIC is going to skew the reading so that the ECU sees 3.2v (14.7:1) and does nothing to richen the lean AFR.
Wouldn't it be better to use the percent mode and only modify the AFR sensor signal where needed and letting the ECU handle closed loop AFR tuning in low load? You can still skew the signal anywhere you want to add fuel while allowing the ECU to take care of idle and low rpm tuning. I suspect that overriding the AFR sensor has a lot to do with the idle problems and inability to adjust for temp and altitude changes that so many FIC users experience.
well i see a few reasons, 1 most people think the car runs like poop when the stft and ltft arent near zero, this is not true the ecu will control fueling and car will still run 14.7 UNLESS which is another reason the injectors are too large for correction
Thread Starter
Joined: Feb 2008
Posts: 11,271
From: Houston, TX
1. It is sorta stickied, there were sooo many sticky threads that the mods thought it would be better to gather them up in one place. However peeps don't look there very often.
2. You are correct that when skewing the o2 sig you mis out on some fuel correction, however the o2 is not the only sensor that deals with fuel. In Weather changes the maf sensor will add or subtract fuel based on temp and flow, it does a good enough job of it that as far a weather changes are concerned the o2 isn't needed for that particular function. Remember the o2 has the last say in fuel, maf has the first say (so to speak). So it's a must that Toyota designed the maf to be somewhat accurate and within a specific range. To test that idea simply unplug the primary o2 sensor and start the car. The car will start and run fairly normal, next take a look at your afr, if maf is clean and in good working order afr will be within reason (all done on stock car of course). Mind you it will not be perfect but not extreme either.
The main point of skewing the o2 sig is part throttle boost. Try as you might to tune using only a fuel map or maf sig ultimately you get owned by the o2 sensor in closed loop operation. It sucks but it's true. The ecu will create it's fuel trims eventually and cut the fat.
As far as using the o2 map in percent mode its a bit sketchy. I can tell you right off that setting it to percent and having the map filled with zero's will screw your world up. Iv tried it twice, once stock and once boosted. Car ran fine for a day, next day I get half way to work and the car damn near beat me to death with all the jerking it was doing. So I don't play with the percent mod based on that experience.
Now back to part throttle boost (boosting in closed loop), is it ok to have a 14.7 afr for such slight boost as 1 to 3 psi? That's a question that can have sooo many answers to. Iv done it and so have many others, some get away with it simply cause their turbo does not flow alot of air or cause they are pulling a bit of timing, or the knock sensor is saving their butts. Knock requires the right conditions to be present and it's hard to say at what point exactly it will hit, so you do your best to keep your tuning strategy in a known safe area. Not to mention the fact that if you are pushing 3psi with an afr of 14.7 you know you are not making the most power possible for that boost level. Personally I can make 2 psi and be in closed loop. I really dont beleave it's that big of a deal to run an afr like that on such a small amount of boost for the turbo I have but I really don't want to tell people that cause they may take that idea a step further which could be a step too far. As you've said befor Fred our knock sensors do work and I'm sure it's saved my butt a time or two however our engines are not immune from knock or scattering themselves on the road or track. So it becomes a question of where do you draw the line to keep your engine safe. I feel closed loop tuning is more about keeping a safety margin.
Just to add I have a theory that if you have a large enough turbo that requires more throttle input to spool, enough to place the ecu in open loop, you can forget about ever having the need for closed loop control.
I'll add more in a min though, gotta run. Didn't want to loose my train of thought so I thought I'd start the answer
2. You are correct that when skewing the o2 sig you mis out on some fuel correction, however the o2 is not the only sensor that deals with fuel. In Weather changes the maf sensor will add or subtract fuel based on temp and flow, it does a good enough job of it that as far a weather changes are concerned the o2 isn't needed for that particular function. Remember the o2 has the last say in fuel, maf has the first say (so to speak). So it's a must that Toyota designed the maf to be somewhat accurate and within a specific range. To test that idea simply unplug the primary o2 sensor and start the car. The car will start and run fairly normal, next take a look at your afr, if maf is clean and in good working order afr will be within reason (all done on stock car of course). Mind you it will not be perfect but not extreme either.
The main point of skewing the o2 sig is part throttle boost. Try as you might to tune using only a fuel map or maf sig ultimately you get owned by the o2 sensor in closed loop operation. It sucks but it's true. The ecu will create it's fuel trims eventually and cut the fat.
As far as using the o2 map in percent mode its a bit sketchy. I can tell you right off that setting it to percent and having the map filled with zero's will screw your world up. Iv tried it twice, once stock and once boosted. Car ran fine for a day, next day I get half way to work and the car damn near beat me to death with all the jerking it was doing. So I don't play with the percent mod based on that experience.
Now back to part throttle boost (boosting in closed loop), is it ok to have a 14.7 afr for such slight boost as 1 to 3 psi? That's a question that can have sooo many answers to. Iv done it and so have many others, some get away with it simply cause their turbo does not flow alot of air or cause they are pulling a bit of timing, or the knock sensor is saving their butts. Knock requires the right conditions to be present and it's hard to say at what point exactly it will hit, so you do your best to keep your tuning strategy in a known safe area. Not to mention the fact that if you are pushing 3psi with an afr of 14.7 you know you are not making the most power possible for that boost level. Personally I can make 2 psi and be in closed loop. I really dont beleave it's that big of a deal to run an afr like that on such a small amount of boost for the turbo I have but I really don't want to tell people that cause they may take that idea a step further which could be a step too far. As you've said befor Fred our knock sensors do work and I'm sure it's saved my butt a time or two however our engines are not immune from knock or scattering themselves on the road or track. So it becomes a question of where do you draw the line to keep your engine safe. I feel closed loop tuning is more about keeping a safety margin.
Just to add I have a theory that if you have a large enough turbo that requires more throttle input to spool, enough to place the ecu in open loop, you can forget about ever having the need for closed loop control.
I'll add more in a min though, gotta run. Didn't want to loose my train of thought so I thought I'd start the answer
Last edited by crush02342002; Nov 16, 2011 at 01:45 AM.
Thanks, I guess I didn't look hard enough in the stickies.
2. You are correct that when skewing the o2 sig you mis out on some fuel correction, however the o2 is not the only sensor that deals with fuel. In Weather changes the maf sensor will add or subtract fuel based on temp and flow, it does a good enough job of it that as far a weather changes are concerned the o2 isn't needed for that particular function. Remember the o2 has the last say in fuel, maf has the first say (so to speak). So it's a must that Toyota designed the maf to be somewhat accurate and within a specific range. To test that idea simply unplug the primary o2 sensor and start the car. The car will start and run fairly normal, next take a look at your afr, if maf is clean and in good working order afr will be within reason (all done on stock car of course). Mind you it will not be perfect but not extreme either.
I agree that the MAS is very accurate however not as much when it's placed into a different size pipe and the IAT is measuring pre-turbo air rather than post-IC air. In my own case I've found that on very hot days I'll develop a lean AFR idle condition that goes away as soon as the measured IAT drops. It seems as though the actual IAT is lower post-IC than it was when measured at the air filter. If left to idle long enough the ECU eventually adjusts the LTFT based on O2 feedback but the trims are way off from where they normally are and should be.
The main point of skewing the o2 sig is part throttle boost. Try as you might to tune using only a fuel map or maf sig ultimately you get owned by the o2 sensor in closed loop operation. It sucks but it's true. The ecu will create it's fuel trims eventually and cut the fat.
As far as using the o2 map in percent mode its a bit sketchy. I can tell you right off that setting it to percent and having the map filled with zero's will screw your world up. Iv tried it twice, once stock and once boosted. Car ran fine for a day, next day I get half way to work and the car damn near beat me to death with all the jerking it was doing. So I don't play with the percent mod based on that experience.
That sucks. I had hoped that the FIC actually worked correctly using percentage mode. I know I tried it before but can't remember how well it worked. In theory a zero would result in no skew and -32% would result in 12.6:1. However if it doesn't work...
Now back to part throttle boost (boosting in closed loop), is it ok to have a 14.7 afr for such slight boost as 1 to 3 psi? That's a question that can have sooo many answers to. Iv done it and so have many others, some get away with it simply cause their turbo does not flow alot of air or cause they are pulling a bit of timing, or the knock sensor is saving their butts. Knock requires the right conditions to be present and it's hard to say at what point exactly it will hit, so you do your best to keep your tuning strategy in a known safe area. Not to mention the fact that if you are pushing 3psi with an afr of 14.7 you know you are not making the most power possible for that boost level. Personally I can make 2 psi and be in closed loop. I really dont beleave it's that big of a deal to run an afr like that on such a small amount of boost for the turbo I have but I really don't want to tell people that cause they may take that idea a step further which could be a step too far. As you've said befor Fred our knock sensors do work and I'm sure it's saved my butt a time or two however our engines are not immune from knock or scattering themselves on the road or track. So it becomes a question of where do you draw the line to keep your engine safe. I feel closed loop tuning is more about keeping a safety margin.
Just to add I have a theory that if you have a large enough turbo that requires more throttle input to spool, enough to place the ecu in open loop, you can forget about ever having the need for closed loop control.
Just to add I have a theory that if you have a large enough turbo that requires more throttle input to spool, enough to place the ecu in open loop, you can forget about ever having the need for closed loop control.
I'll add more in a min though, gotta run. Didn't want to loose my train of thought so I thought I'd start the answer
This may be another one of those instances where sound theory doesn't stand up to the reality of how the FIC actually works in the real world. I was really hoping that the damb thing worked in percentage mode since AEM didn't include any "no change" option in voltage mode.
Thread Starter
Joined: Feb 2008
Posts: 11,271
From: Houston, TX
the only reason I spelled things out was for those who may read this stuff and dont have a clue about tuning. I wasnt preaching at ya.
There are other options Fred to tune the o2 map, you have offset mode. btw way i dont think the voltage mode is fixed since there is a fixed mode available.
btw its been prolly 3 weeks and all my issues are gone now...woohoo. this is going to sound pretty stupid but the main problem was my primary o2 sensor connector wouldnt plug firmly in, the weather seal was bunching up in the connector so that the pins would just barely make contact. kinda made the sig seem like I had put a light resistor on it. the connector would clip togather but just barely and you had to press them togather harder than normal to get it to clip. Go figure it was something as simple as that. I found that i do have a loose connection or short in the pnp harness, I placed my fic in my glove box and the next thing I know the car will not idle down past 1500rpms. I drove the car for a few miles to see if it would clear up but every red light and stop sign the car still idled at 1500. I pulled the fic out of the glove box and all of a sudden things went back to normal. put the fic back in the glove box and im at 1500 again. Now i keep my fic in my floor board...lol
There are other options Fred to tune the o2 map, you have offset mode. btw way i dont think the voltage mode is fixed since there is a fixed mode available.
btw its been prolly 3 weeks and all my issues are gone now...woohoo. this is going to sound pretty stupid but the main problem was my primary o2 sensor connector wouldnt plug firmly in, the weather seal was bunching up in the connector so that the pins would just barely make contact. kinda made the sig seem like I had put a light resistor on it. the connector would clip togather but just barely and you had to press them togather harder than normal to get it to clip. Go figure it was something as simple as that. I found that i do have a loose connection or short in the pnp harness, I placed my fic in my glove box and the next thing I know the car will not idle down past 1500rpms. I drove the car for a few miles to see if it would clear up but every red light and stop sign the car still idled at 1500. I pulled the fic out of the glove box and all of a sudden things went back to normal. put the fic back in the glove box and im at 1500 again. Now i keep my fic in my floor board...lol
Okay, I thought you might have misunderstood what I wanted to do. I often do the same thing and get the same reaction when I add some info for everyone that the addressee already knows.
Anyway, I didn't remember how the FIC handled zeros in the O2 map when in voltage mode so I called AEM tech support yesterday to ask. I was told that a zero would tell the FIC to supply zero volts. Today I double-checked the FIC tuning guide to find this:
• "Voltage" mode - The F/IC outputs a voltage, which is determined by the corresponding cells in the "O2 Map". In the "Voltage" mode, for an "O2 Map" cell value of 2.5, the F/IC will output 2.5 volts. In "Voltage" mode, a cell value of 0 makes no change, NOT an output voltage of 0 volts.
Serves me right for listening to a AEM tech douche again... Now all I have to do is see who is right but so far it's always been the guy who wrote the tuning guide. My biggest problem is not having a FIC and trying to tune one for a guy who lives 3000 miles away.
Good catch on the AFR sensor plug! That's the sort of problem that can have you pulling your hair out for a long time. I'm glad to hear that you have it all sorted now. Too bad about the harness problem though, that could be a real PITA to fix.
Anyway, I didn't remember how the FIC handled zeros in the O2 map when in voltage mode so I called AEM tech support yesterday to ask. I was told that a zero would tell the FIC to supply zero volts. Today I double-checked the FIC tuning guide to find this:
• "Voltage" mode - The F/IC outputs a voltage, which is determined by the corresponding cells in the "O2 Map". In the "Voltage" mode, for an "O2 Map" cell value of 2.5, the F/IC will output 2.5 volts. In "Voltage" mode, a cell value of 0 makes no change, NOT an output voltage of 0 volts.
Serves me right for listening to a AEM tech douche again... Now all I have to do is see who is right but so far it's always been the guy who wrote the tuning guide. My biggest problem is not having a FIC and trying to tune one for a guy who lives 3000 miles away.
Good catch on the AFR sensor plug! That's the sort of problem that can have you pulling your hair out for a long time. I'm glad to hear that you have it all sorted now. Too bad about the harness problem though, that could be a real PITA to fix.
Thread Starter
Joined: Feb 2008
Posts: 11,271
From: Houston, TX
Okay, I thought you might have misunderstood what I wanted to do. I often do the same thing and get the same reaction when I add some info for everyone that the addressee already knows.
Anyway, I didn't remember how the FIC handled zeros in the O2 map when in voltage mode so I called AEM tech support yesterday to ask. I was told that a zero would tell the FIC to supply zero volts. Today I double-checked the FIC tuning guide to find this:
• "Voltage" mode - The F/IC outputs a voltage, which is determined by the corresponding cells in the "O2 Map". In the "Voltage" mode, for an "O2 Map" cell value of 2.5, the F/IC will output 2.5 volts. In "Voltage" mode, a cell value of 0 makes no change, NOT an output voltage of 0 volts.
Serves me right for listening to a AEM tech douche again... Now all I have to do is see who is right but so far it's always been the guy who wrote the tuning guide. My biggest problem is not having a FIC and trying to tune one for a guy who lives 3000 miles away.
Good catch on the AFR sensor plug! That's the sort of problem that can have you pulling your hair out for a long time. I'm glad to hear that you have it all sorted now. Too bad about the harness problem though, that could be a real PITA to fix.
Anyway, I didn't remember how the FIC handled zeros in the O2 map when in voltage mode so I called AEM tech support yesterday to ask. I was told that a zero would tell the FIC to supply zero volts. Today I double-checked the FIC tuning guide to find this:
• "Voltage" mode - The F/IC outputs a voltage, which is determined by the corresponding cells in the "O2 Map". In the "Voltage" mode, for an "O2 Map" cell value of 2.5, the F/IC will output 2.5 volts. In "Voltage" mode, a cell value of 0 makes no change, NOT an output voltage of 0 volts.
Serves me right for listening to a AEM tech douche again... Now all I have to do is see who is right but so far it's always been the guy who wrote the tuning guide. My biggest problem is not having a FIC and trying to tune one for a guy who lives 3000 miles away.
Good catch on the AFR sensor plug! That's the sort of problem that can have you pulling your hair out for a long time. I'm glad to hear that you have it all sorted now. Too bad about the harness problem though, that could be a real PITA to fix.
Banned
Scionetics
KAD
SL Member
Joined: Oct 2005
Posts: 11,936
From: Western NY
1. It is sorta stickied, there were sooo many sticky threads that the mods thought it would be better to gather them up in one place. However peeps don't look there very often.
2. You are correct that when skewing the o2 sig you mis out on some fuel correction, however the o2 is not the only sensor that deals with fuel. In Weather changes the maf sensor will add or subtract fuel based on temp and flow, it does a good enough job of it that as far a weather changes are concerned the o2 isn't needed for that particular function. Remember the o2 has the last say in fuel, maf has the first say (so to speak). So it's a must that Toyota designed the maf to be somewhat accurate and within a specific range. To test that idea simply unplug the primary o2 sensor and start the car. The car will start and run fairly normal, next take a look at your afr, if maf is clean and in good working order afr will be within reason (all done on stock car of course). Mind you it will not be perfect but not extreme either.
The main point of skewing the o2 sig is part throttle boost. Try as you might to tune using only a fuel map or maf sig ultimately you get owned by the o2 sensor in closed loop operation. It sucks but it's true. The ecu will create it's fuel trims eventually and cut the fat.
As far as using the o2 map in percent mode its a bit sketchy. I can tell you right off that setting it to percent and having the map filled with zero's will screw your world up. Iv tried it twice, once stock and once boosted. Car ran fine for a day, next day I get half way to work and the car damn near beat me to death with all the jerking it was doing. So I don't play with the percent mod based on that experience.
Now back to part throttle boost (boosting in closed loop), is it ok to have a 14.7 afr for such slight boost as 1 to 3 psi? That's a question that can have sooo many answers to. Iv done it and so have many others, some get away with it simply cause their turbo does not flow alot of air or cause they are pulling a bit of timing, or the knock sensor is saving their butts. Knock requires the right conditions to be present and it's hard to say at what point exactly it will hit, so you do your best to keep your tuning strategy in a known safe area. Not to mention the fact that if you are pushing 3psi with an afr of 14.7 you know you are not making the most power possible for that boost level. Personally I can make 2 psi and be in closed loop. I really dont beleave it's that big of a deal to run an afr like that on such a small amount of boost for the turbo I have but I really don't want to tell people that cause they may take that idea a step further which could be a step too far. As you've said befor Fred our knock sensors do work and I'm sure it's saved my butt a time or two however our engines are not immune from knock or scattering themselves on the road or track. So it becomes a question of where do you draw the line to keep your engine safe. I feel closed loop tuning is more about keeping a safety margin.
Just to add I have a theory that if you have a large enough turbo that requires more throttle input to spool, enough to place the ecu in open loop, you can forget about ever having the need for closed loop control.
I'll add more in a min though, gotta run. Didn't want to loose my train of thought so I thought I'd start the answer
2. You are correct that when skewing the o2 sig you mis out on some fuel correction, however the o2 is not the only sensor that deals with fuel. In Weather changes the maf sensor will add or subtract fuel based on temp and flow, it does a good enough job of it that as far a weather changes are concerned the o2 isn't needed for that particular function. Remember the o2 has the last say in fuel, maf has the first say (so to speak). So it's a must that Toyota designed the maf to be somewhat accurate and within a specific range. To test that idea simply unplug the primary o2 sensor and start the car. The car will start and run fairly normal, next take a look at your afr, if maf is clean and in good working order afr will be within reason (all done on stock car of course). Mind you it will not be perfect but not extreme either.
The main point of skewing the o2 sig is part throttle boost. Try as you might to tune using only a fuel map or maf sig ultimately you get owned by the o2 sensor in closed loop operation. It sucks but it's true. The ecu will create it's fuel trims eventually and cut the fat.
As far as using the o2 map in percent mode its a bit sketchy. I can tell you right off that setting it to percent and having the map filled with zero's will screw your world up. Iv tried it twice, once stock and once boosted. Car ran fine for a day, next day I get half way to work and the car damn near beat me to death with all the jerking it was doing. So I don't play with the percent mod based on that experience.
Now back to part throttle boost (boosting in closed loop), is it ok to have a 14.7 afr for such slight boost as 1 to 3 psi? That's a question that can have sooo many answers to. Iv done it and so have many others, some get away with it simply cause their turbo does not flow alot of air or cause they are pulling a bit of timing, or the knock sensor is saving their butts. Knock requires the right conditions to be present and it's hard to say at what point exactly it will hit, so you do your best to keep your tuning strategy in a known safe area. Not to mention the fact that if you are pushing 3psi with an afr of 14.7 you know you are not making the most power possible for that boost level. Personally I can make 2 psi and be in closed loop. I really dont beleave it's that big of a deal to run an afr like that on such a small amount of boost for the turbo I have but I really don't want to tell people that cause they may take that idea a step further which could be a step too far. As you've said befor Fred our knock sensors do work and I'm sure it's saved my butt a time or two however our engines are not immune from knock or scattering themselves on the road or track. So it becomes a question of where do you draw the line to keep your engine safe. I feel closed loop tuning is more about keeping a safety margin.
Just to add I have a theory that if you have a large enough turbo that requires more throttle input to spool, enough to place the ecu in open loop, you can forget about ever having the need for closed loop control.
I'll add more in a min though, gotta run. Didn't want to loose my train of thought so I thought I'd start the answer
The knock logic on the stock ECU is very aggressive. Toyota is always searching for the max timing to push to knock threshold. It will ramp in timing, find some trace knock, then back off a degree or two...then do it all over again. This constant flux of ignition timing makes for very inconsistent AFRs, when coupled with temp changes, IC heat soaking and baro changes....it's a very different animal. Changing just timing anywhere from -4 to +4 from a certain load point will dynamically change the fueling delivered to the engine. If you want to experiment, you can see this real time with a scan tool, a wideband and the FIC. It's even more pronounced with a standalone EMS.