VE Table Cracked
07-06-2004, 08:01 AM
#141
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Originally Posted by gameover
The thing to realise is the VE table is not a VE table in the traditional sense it is a cylinder airmass table.
07-06-2004, 08:51 AM
#142
Originally Posted by HumpinSS
After doing some thinking about this comment last night and taking into consideration gameover is an expert in this dept. I have come to the conclusion that LTFT's can be applied to the ve table. If the PCM is trying to maintain a 14.7:1 ratio that mean to me there is a certain amount of gas that needs to be shot to acheive this. If you have x amount of grams of air, you need x amount of gas entering the cylinder to acheive 14:1. The LTFTs show you how much you are off by based on the MAF, the o2s and all the other airmass algortihms used in calculating this. The IFR table to me is jsut like the maf table. If they are stock why mess with them. Since the ve table isnt a VE table but an airmass table, I think I am gonna use the LTFTs on the ve table and see what effects it has on the car.
joel
07-06-2004, 09:23 AM
#143
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Man the more i jump into this tuning the more i see a wideband o2 being imperative. Time to pony up and give innovative a call. 
. Damn i was trying to hold out until we had better means of scanning without buying all those other cables or wiring it to the A/c pressure switch.
. Damn i was trying to hold out until we had better means of scanning without buying all those other cables or wiring it to the A/c pressure switch.
07-07-2004, 10:02 AM
#144
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It looks like a horserace to me between Innovate and the
Wideband Commander unit (dynotune.org --->); the latter
bundles up a few more things (like the gauge). You could
also run a 0-1V output into the rear O2 on one side if you
preferred not messing with the A/C sender. Just get a
junk O2 and cut its pigtail off, cobble it up for plug-'n'-play.
If the unit you get is only 0-4V (0-5V) you would want to
resistor-divide it down but some provide a 0-1V as well,
for the express purpose of feeding an O2 sense input.
Wideband Commander unit (dynotune.org --->); the latter
bundles up a few more things (like the gauge). You could
also run a 0-1V output into the rear O2 on one side if you
preferred not messing with the A/C sender. Just get a
junk O2 and cut its pigtail off, cobble it up for plug-'n'-play.
If the unit you get is only 0-4V (0-5V) you would want to
resistor-divide it down but some provide a 0-1V as well,
for the express purpose of feeding an O2 sense input.
07-07-2004, 02:40 PM
#145
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Originally Posted by jimmyblue
It looks like a horserace to me between Innovate and the
Wideband Commander unit (dynotune.org --->); the latter
bundles up a few more things (like the gauge). You could
also run a 0-1V output into the rear O2 on one side if you
preferred not messing with the A/C sender. Just get a
junk O2 and cut its pigtail off, cobble it up for plug-'n'-play.
If the unit you get is only 0-4V (0-5V) you would want to
resistor-divide it down but some provide a 0-1V as well,
for the express purpose of feeding an O2 sense input.
Wideband Commander unit (dynotune.org --->); the latter
bundles up a few more things (like the gauge). You could
also run a 0-1V output into the rear O2 on one side if you
preferred not messing with the A/C sender. Just get a
junk O2 and cut its pigtail off, cobble it up for plug-'n'-play.
If the unit you get is only 0-4V (0-5V) you would want to
resistor-divide it down but some provide a 0-1V as well,
for the express purpose of feeding an O2 sense input.
Hey Jimmyblue, I was reading your post about needing a very accurate wideband and I don't know if you are familar with TechEdge but if not here is a little bit of info about their products. I did several months of research on this and their systems seem to have the fastest sampling rate, multiple inputs and outputs, more memory, all controlled by firmware that is updateable on their site. With Dynamic Calibration software you can run in windows to calibrate it etc.. The logging serial output is publically documented so you can develop your own integrated logging software which I am working on at the moment. It has so many features for the money it is hard to go wrong in not ordering one.
I bought a complete system (the 2B0, their latest edition) for about $400.00 (US) with a sensor. This is without a display unit but I use a laptop for this anyway or if you have a palm you can just use one of those for the display if you don't want a laptop in your car all the time. The display is pretty cheap but I figured since I already have a Palm T I could use this most of the time and do datalogging on it when I needed to or bring my laptop in the car when I needed to do other things. It also has memory to do datalogging onboard so you can download it later to you computer. It can sample up to 50 frames a second as well or whatever you specify. I could go on but you see this is not your standard WB system for $450-500 (US) with a display and sensor. Or you could purchase their 2BA system with a display for about $350.00-400.00 (US) with a sensor, it just has less onboard memory and does not have the aluminum case and a few other features nothing really affecting the accuracy of the system.
They have systems that work with the 6066 but the 7057 sensor is what they recommend for most users. Their site has enough info to satisfy even the most demanding person of technical knowledge as you can order their 2A0 in kit form and build it yourself if you are wanting to save even more but I don't recommend unless you have a very good soldering iron and good test equipment. If this is of interest just search google for wbo2 or TechEdge as they are not a sponser and I don't want to post a link to a non sponser and get in trouble with the admin.
07-07-2004, 03:09 PM
#146
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I will have to look at them again; the last time
I checked they were still using the more pricey
NTK (?) wideband sensors and the kit + sensor
was a lot more $ all-told than later competition.
I checked they were still using the more pricey
NTK (?) wideband sensors and the kit + sensor
was a lot more $ all-told than later competition.
07-07-2004, 04:43 PM
#147
I agree about the maf being inaccurate at massflow, but in the low rpm, low kpa areas you are talking about the target a/f ratio is gonna be 14.7:1 cause you're not gonna be in PE mode. The stock o2 sensors are plenty accurate around 14.7:1 so it seems to me they'd be fine to use for low rpm, low kpa tuning.
07-07-2004, 04:55 PM
#148
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this is what i figured also. GM knows the maf is inaccurate at low rpm so there are most likely complex algorithims in place that maintain target ratio blending in map and o2 voltage outputs
07-08-2004, 06:33 PM
#149
Originally Posted by P Mack
I agree about the maf being inaccurate at massflow, but in the low rpm, low kpa areas you are talking about the target a/f ratio is gonna be 14.7:1 cause you're not gonna be in PE mode. The stock o2 sensors are plenty accurate around 14.7:1 so it seems to me they'd be fine to use for low rpm, low kpa tuning.
joel Last edited by Bink; 07-08-2004 at 06:39 PM.
07-08-2004, 06:38 PM
#150
Originally Posted by HumpinSS
this is what i figured also. GM knows the maf is inaccurate at low rpm so there are most likely complex algorithims in place that maintain target ratio blending in map and o2 voltage outputs\
A good way to assess a new VE table is to see how close your actual AFR is to the F/A Multiplier, AKA Stoich table.
08-02-2004, 12:22 PM
#154
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Nogo'sve% = MAF.gp/s*(IAC+273)/((346*RPM)*MAP)*212544
gameover's = Ve= g/cy * ((IAT+273)*5120)/MAP(kpa)/cyl colume/178 derived from original formula of
ve . (178.33) . (0.708) . map / (iat+273) . 5120 = 0.85 g/cyl
gameover's = Ve= g/cy * ((IAT+273)*5120)/MAP(kpa)/cyl colume/178 derived from original formula of
ve . (178.33) . (0.708) . map / (iat+273) . 5120 = 0.85 g/cyl
08-02-2004, 03:42 PM
#155
Originally Posted by HumpinSS
Nogo'sve% = MAF.gp/s*(IAC+273)/((346*RPM)*MAP)*212544
gameover's = Ve= g/cy * ((IAT+273)*5120)/MAP(kpa)/cyl colume/178 derived from original formula of
ve . (178.33) . (0.708) . map / (iat+273) . 5120 = 0.85 g/cyl
gameover's = Ve= g/cy * ((IAT+273)*5120)/MAP(kpa)/cyl colume/178 derived from original formula of
ve . (178.33) . (0.708) . map / (iat+273) . 5120 = 0.85 g/cyl
joel
08-02-2004, 03:44 PM
#156
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From the scanner. When i exported the file to a csv I also chose to export rpm which gave me my reference. In excel i then ran the formulas on the columns i needed.
08-02-2004, 03:51 PM
#157
Originally Posted by HumpinSS
From the scanner. When i exported the file to a csv I also chose to export rpm which gave me my reference. In excel i then ran the formulas on the columns i needed.
Seriously that's awesome.
Are they within, or near, 1% for all values??? 
NoGo's AMAZING!!!!!
08-03-2004, 09:18 AM
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Originally Posted by NoGo
I have been working on the VE table quite a bit lately and I think I found the solution.
Thanks to gameover for some key hints.
The VE table looks as though it is in meters cubed, it is just not used like a conventional VE table. The VE values are such that the PCM can directly backcalculate to g/cyl, the primary means to determine fueling and timing.
This is what makes it so confusing. You can't solve for air mass, you have to solve for g/cyl.
Anyhoo, here is the equation
VE = ((massflow * IAT / (MAP * RPM * Displacement))
Massflow: grams/sec
IAT: Degrees Kelvin
MAP: Bar
RPM: Duh!
Displacement: Cubic Meters
To solve for the massflow in g/sec simply re-arrange the equation.
Massflow = (VE * MAP * RPM * Displacement) / IAT
My old method of "Divide by 30" works okay because we are inadvertantly solving for a volume ratio. The molar mass of air is 28.96 g/mol.
I have compared the above equation to every bit of data that I have ever collected for a stock car, and the data matches up perfectly.
Any corrections, comments, or blinding errors please let me know.
Thanks,
Kevin
Thanks to gameover for some key hints.
The VE table looks as though it is in meters cubed, it is just not used like a conventional VE table. The VE values are such that the PCM can directly backcalculate to g/cyl, the primary means to determine fueling and timing.
This is what makes it so confusing. You can't solve for air mass, you have to solve for g/cyl.
Anyhoo, here is the equation
VE = ((massflow * IAT / (MAP * RPM * Displacement))
Massflow: grams/sec
IAT: Degrees Kelvin
MAP: Bar
RPM: Duh!
Displacement: Cubic Meters
To solve for the massflow in g/sec simply re-arrange the equation.
Massflow = (VE * MAP * RPM * Displacement) / IAT
My old method of "Divide by 30" works okay because we are inadvertantly solving for a volume ratio. The molar mass of air is 28.96 g/mol.
I have compared the above equation to every bit of data that I have ever collected for a stock car, and the data matches up perfectly.
Any corrections, comments, or blinding errors please let me know.
Thanks,
Kevin