Ok...I went racing last Friday...car ran good but still rich...my A/F table is set ...with the boost 24-26 PSI... around 11.2-11.3 at WOT 5500-6000 RPM's...the spark is 24 degrees...first run I saw that most of the run XFI was pulling fuel...O2 corrections were from -6.5 to -10.2 the entire run...the -10.2was closer to the end of run which kind of surprised me...I thought near the end of the run the car would require more fuel so the O2 correction would be less...??...so I adjusted the cells around the WOT area in the VE table by trimming the values -3%...after second run O2 correction had gone down near the beginning of the run but end of the run...still -10.2..??...now I'm confused...so I trim another -2%...same cells...third run...O2 correction numbers didn't seem to change at all...still -10.2 end of run...the strange thing is the Actual A/F was 11.2-11.3 but the O2 correction was -10.2...how can that be...why is it still pulling fuel if the A/F is right on???...what am I doing wrong here?...or is there something wrong with the car...
VE Table changes...totally confused
- Thread starter MSDGN
- Start date
callmeebryan
Member
- Joined
- Jun 24, 2007
You're obviously running alky right? Or race gas?
callmeebryan
Member
- Joined
- Jun 24, 2007
Here are a couple XFI logs from my first run and last run...only difference between the two is I trimmed the VE table in the WOT cells by -5% for the last run...to me it's still running very rich...or am I reading the log wrong?...the log name suffixed with "A" is the first run..."C" is last run...
callmeebryan
Member
- Joined
- Jun 24, 2007
Holy crap,in the first log 9 ticks of knock on launch. 
12.2 AFR at 18lbs is a little lean. By that time you want to be in the mid to low 11's..... I understand that you are keeping it a little lean to help build boost at the line, but once you get up above 12psi your car builts boost perfectly so you should probably richin it up a little bit in those VE tables.
Say you are using 20% methanol and 80% gasoline.
The combined A/F is simply %A/F 1 + %A/F 2
So for 20% methanol, .2(6.4) + .8(14.6)= 12.96
This still doesn't help you since your AFR meter is calibrated for a gasoline stoich ratio of 14.6. You can set your meter to read Lambda, then multiply by your combined A/F ratio to find your correct A/F.
Hope this helps.
12.2 AFR at 18lbs is a little lean. By that time you want to be in the mid to low 11's..... I understand that you are keeping it a little lean to help build boost at the line, but once you get up above 12psi your car builts boost perfectly so you should probably richin it up a little bit in those VE tables.
Say you are using 20% methanol and 80% gasoline.
The combined A/F is simply %A/F 1 + %A/F 2
So for 20% methanol, .2(6.4) + .8(14.6)= 12.96
This still doesn't help you since your AFR meter is calibrated for a gasoline stoich ratio of 14.6. You can set your meter to read Lambda, then multiply by your combined A/F ratio to find your correct A/F.
Hope this helps.
The knock on launch is false...I tried a new setting on the front shocks and the car was launching like crap...think it was bottoming out on something or hitting something...that's where the false knock came from...before I made the shock change I never had any knock at all...I don't run anything but pure C-16 race gas...not sure I agree with you that I should richen it up in the VE table...it's pulling a lot of fuel near the end of the run...shouldn't I try to lean it out a little...or are you saying I should richen it up a little in the VE table around the beginning of the run...right now I'm more concerned about it being so rich at the end of the run...seems like that would kill some MPH...
callmeebryan
Member
- Joined
- Jun 24, 2007
Holy crap,in the first log 9 ticks of knock on launch.
12.2 AFR at 18lbs is a little lean. By that time you want to be in the mid to low 11's..... I understand that you are keeping it a little lean to help build boost at the line, but once you get up above 12psi your car builts boost perfectly so you should probably richin it up a little bit in those VE tables.
Say you are using 20% methanol and 80% gasoline.
The combined A/F is simply %A/F 1 + %A/F 2
So for 20% methanol, .2(6.4) + .8(14.6)= 12.96
This still doesn't help you since your AFR meter is calibrated for a gasoline stoich ratio of 14.6. You can set your meter to read Lambda, then multiply by your combined A/F ratio to find your correct A/F.
Hope this helps.
I want to add to this...even though i now know you only run c-16, but just in case someone else reads this.....
What i was posting in this post was showing you what your ACTUAL AFR is, not what the FAST is showing you. The FAST o2 sensor reads the amount of oxygen particles in the exhaust. It does not care what kind of fuel you are using.
AFR meters display a calculation on a scale of Lambda. Most AFR meters measure in terms of gasoline stoich. So whether you are running 100% 93 octane pump gas, or 80% gasoline/20% methanol, you will tune for the SAME displayed AFR in the FAST, and then make minor adjustments for maximum power with no knock.
Yes, i meant richen it up a little bit in the low end where your car is building boost....and i said that because i saw the 9 degrees of knock. From 0-12 psi its great, then your turbo spools perfectly after that. Maybe add 1 VE to those areas and see how it works.
As far as your car pulling out lots of fuel.... you have a bit of power to be made after you bring that o2 correction within +/- 5%.
Load up your tune in the XFI program, display your VE map, then open up your log. Hide the dashboard on the VE table and it will display lines on your VE that correspond with the log. Scroll through the log and check out what the o2 correction is, and adjust to whatever that correction % is. So if its pulling out 10% fuel, pull out 8% and go from there. If its pulling out 5%, pull out 3-4 %. Etc.
Dont be afraid to pull some out. As long as your O2 correction is set for atleast -10, +15 you will be fine. It will make the necessary adjustments where need be.
Dusty Bradford
Well-Known Member
- Joined
- May 24, 2001
Holy crap,in the first log 9 ticks of knock on launch.
12.2 AFR at 18lbs is a little lean. By that time you want to be in the mid to low 11's..... I understand that you are keeping it a little lean to help build boost at the line, but once you get up above 12psi your car builts boost perfectly so you should probably richin it up a little bit in those VE tables.
Say you are using 20% methanol and 80% gasoline.
The combined A/F is simply %A/F 1 + %A/F 2
So for 20% methanol, .2(6.4) + .8(14.6)= 12.96
This still doesn't help you since your AFR meter is calibrated for a gasoline stoich ratio of 14.6. You can set your meter to read Lambda, then multiply by your combined A/F ratio to find your correct A/F.
Hope this helps.
I have to disagree. 12.2 at 18# with C-16 is not lean at all. Mid-low 11's is for 30+# of boost.
Take about 5% or so out up top where it's pulling 10% and go from there. It's pulling 10% out to meet the a/f target. Pull another 3-4% out and try again until the correction is in the -3% or so range.
I'll keep tweaking the VE table...another question and maybe this is why I didn't see any changes in O2 correction when I modified the VE table...normally when I make a change to the GCT file and the new file gets saved to the XFI box memory a small window pops up telling me that so many bytes have been updated...I made the VE changes after my first and second runs but never saw that window when I saved my changes...did the changes not get loaded into the box?...should I always see that bytes updated window?
callmeebryan
Member
- Joined
- Jun 24, 2007
Any changes that you make in the XFI automatically save to the FAST computer, but doesnt automatically overwrite your gct file. Such that if you make changes and then shut your car off, the FAST will save in its memory the tune you had just before the car shut down.
The only time you should see the "updating bytes" window is when your car is running and you load a new gct file that has different parameters than the current gct in the box memory.
Ok...just want to confirm I'm doing this right so my changes are taking effect...after a run I go back to the pits...shut the car down(key OFF)...PC not connected to XFI...make VE table changes...save GCT file...some time later I fire the car up again for next run...Click File - Read All Tables and select the GCT file I saved with the changes...when I connect the PC to XFI does it automatically load the new file/data?
callmeebryan
Member
- Joined
- Jun 24, 2007
Sort of...
In order for the tune to save to the box memory, the key has to be in the on position, or else you cant connect to the box. I like to do all my changes when the ignition is in the on position so i dont have to reload the map after i save it.
If you do choose to have the key out, say if you want to take the laptop out of the car to a bench or something with you, then yes.... save the map, when you go back in to the car, turn the key to ON (dont start it), load the gct file you just saved, then start the car after its done loading.
Another thing i recommend to everyone. When you make changes, dont keep saving to the same GCT file. I like to make a new GCT file for every change that i make, and make notes in the save box as to what i changed and why. For every GCT file, i put (Name).(Date).(Number of gct for that day...1,2,3,etc).gct. This way, you keep a sort of timeline of all your changes, and you can revert back to any previous gct if the changes you made didnt work out. I have about 45 different gct files in a folder, all organized by date since august 28th.
- Joined
- May 28, 2001
I have to agree with Brian on this. Save a copy of the gct file on your laptop so you know you have a good baseline to work with.
When you make changes to the FAST unit, do it with the ECM hooked up and the ingnition on. Make the changes in the VE table and it will save them right then.
Be careful with the correction tables using the WB sensor. You can set the correction tables to subtract no more than 5% and add no more than 20% to any cell in the VE table.
Dont be afraid with 12.2 AF ratio at 18 psi. Get the turbo spinning and then set the AF ratio to 11.5. You can always make changes just do it in small steps and watch what it does.
When you make changes to the FAST unit, do it with the ECM hooked up and the ingnition on. Make the changes in the VE table and it will save them right then.
Be careful with the correction tables using the WB sensor. You can set the correction tables to subtract no more than 5% and add no more than 20% to any cell in the VE table.
Dont be afraid with 12.2 AF ratio at 18 psi. Get the turbo spinning and then set the AF ratio to 11.5. You can always make changes just do it in small steps and watch what it does.
callmeebryan
Member
- Joined
- Jun 24, 2007
Whats the point? That doesnt make sense. The ECU will stay online if you cut the ignition or if the car dies (engine stalls or something), as long as the key is still in the on position. So there is no reason for the ECU to unload its tune like you mentioned.
When you cut power to the fast, you cut power from the fast to your laptop....
If you make changes, then shut the car off (without manually saving the GCT file), when you go to turn the car back on, the tune that was in the box right before power was cut (so, after you have made those changes) is already preloaded. Its saved into the box memory.
So lets say you theoretically get a new laptop and never saved your GCT files... no big deal. The last tune is "saved" into the FAST box memory regardless if you saved that particular file as a GCT or not. Plug in that laptop, open up the FAST software, turn the key to the ON position, CONNECT the laptop to the FAST, and it will automatically load the tune that is in the FAST memory, and your laptop will display that tune. You can then save it, tweak it, etc. If this wasnt the case, you would have to load up your tune EVERY time you have to start the car, and thats just impractical.
What you said makes it sound like you cant make changes in LIVE mode because it wont save your changes unless you manually save the GCT... and thats not the case.
yeh, i said that in previous posts.
Bottom line.... Save a new GCT after EVERY change you make.... its just that simple.
Craig Smith
That was easy!
- Joined
- May 25, 2001
Actually, I believe Buzzard is correct. Real time changes are made in a volatile section of the XFI's memory, and are written to EEPROM when you turn the key off. The changes you made will work in real-time (i.e. you bump up VE values and the car will immediately richen up) but they still are not truly saved inside the XFI as they were with the classic unit.
I believe part of the reasoning behind this is that EEPROM (the area of memory in the XFI's processor where the calibration data, among other things, is stored) has a limited number of write cycles. You can only change it a finite number of times. While this number is huge, working from flash and then dumping the calibration into EEPROM on power-down drastically improves the life expectancy (for lack of a better word) of the EEPROM in the XFI. It's not likely than anyone will ever "use up" an XFI due to this issue, and with this implementation it would be virtually impossible to exceed the maximum number of write cycles.
With the classic unit, every time you hit the page up/down key in a 3D table was a write cycle. Every time you hit the up or down arrow in a 2D table, there's another write cycle. As you may understand from this, they can add up quickly in this manner. IIRC, if you highlight 10 cells and hit the page up key once, there's 10 write cycles.
When you turn the key off, the ECU still stays on for a few seconds, even though the car shuts off. One of the things it does during this time is write the cal data to memory.
I believe part of the reasoning behind this is that EEPROM (the area of memory in the XFI's processor where the calibration data, among other things, is stored) has a limited number of write cycles. You can only change it a finite number of times. While this number is huge, working from flash and then dumping the calibration into EEPROM on power-down drastically improves the life expectancy (for lack of a better word) of the EEPROM in the XFI. It's not likely than anyone will ever "use up" an XFI due to this issue, and with this implementation it would be virtually impossible to exceed the maximum number of write cycles.
With the classic unit, every time you hit the page up/down key in a 3D table was a write cycle. Every time you hit the up or down arrow in a 2D table, there's another write cycle. As you may understand from this, they can add up quickly in this manner. IIRC, if you highlight 10 cells and hit the page up key once, there's 10 write cycles.
When you turn the key off, the ECU still stays on for a few seconds, even though the car shuts off. One of the things it does during this time is write the cal data to memory.
callmeebryan
Member
- Joined
- Jun 24, 2007
Hmmpf, i guess the XFI is a little different from the B2B in that sense.... learn something new every day
I stand corrected.That's OK I screwed up anyways somehow...I went to make some changes to the VE table...(I do usually save to a new file each time I make changes)...been a software engineer for 25 years so it's automatic for me...but when I looked at the VE table for the current GCT I noticed the re-scaling and VE changes I had done weren't there???...I must have opened an older GCT file and then overlaid the current one with the old one...I remember at the track I made changes to the VE table...key was off so XFI wasn't connected...I saved the changes to the current file...I know I should have saved to new file but I didn't...I then turned the key on...connected to XFI and clicked on "Read All Tables" and selected the GCT file I was just updating...I was expecting to see the "updating bytes" window that Buzzard mentioned but didn't so I tried a few more things...that must have been when I opened an older GCT and then overlaid the latest GCT...so who knows what GCT I was running with on my last 2 runs...I should be able to just connect to XFI with my laptop and view the VE table that is currently loaded into XFI...I'll bet it's an older one...CRAP!!...question...I assume when working in Online mode you won't see the "updating bytes" message but will you see it every time you make any changes to the GCT file in offline then connect and read that new file?...I'm trying to find out the best procedure at the track for updating the GCT file and getting it loaded into XFI...obviously I screwed up the way I did it...
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