P Mack

iTrader: (6)

The air density is calculated through manifold pressure and temperature. It doesn't account for humidity though, which is why i believe people see their ltft's change without changing their tune.

98A4LS1

iTrader: (1)

Not sure I follow what you are saying since density is mass per volume.

P Mack

iTrader: (6)

It is, but it can be calculated from pressure and temperature using the ideal gas law (line 6 of the attachment).

Here you go.

Bink

P Mack - That's a nice simple derivation! Very straight forward ...I think.

98A4LS1

iTrader: (1)

LOL, thanks P Mack. I really appreciate the reply. I will take a look at it today at work. I use IDL and more everyday, it's second nature being an environmental engineer. I apologize for all of my questions which I'm sure have been asked many times before. I'm trying to come up to speed quickly since I have parts laying around dying to be installed on my '98 Z
Maybe it will be more clear when the software I ordered arrives tomorrow and I start logging and reviewing some data.
Again, muchos gracias!
Great website!

gojo

iTrader: (12)

"{SAE.MAF.gps}*({SAE.IAT.C}+273.15)/(346*{SAE.RPM}*{SAE.MAP.kPa})*6155274.2"
This will match the LS1 Edit values.

TooManyIDs

Did a quick calc for a cell and it does look like a match on the LS1Edit value. Please explain the constants of 346 (cubic inches???) and 6155274.2?

I tried to create a spreadsheet equation using the cylinder volume (mentioned above) as the only constant. Sadly, my attempt to match the LS1Edit table failed.

=(MAF Rate[gm/sec]*((Intake Air Temp[F]+459.67)/1.8)/((MAP[inHg]*0.033863881)*RPM*0.708))

Convert IAT from Farenheit to Kelvin
Convert MAP from in.Hg to Bar

TooManyIDs

gojo,
This looks like what ChrisB posted here:

https://ls1tech.com/forums/showpost....9&postcount=76

except for the last constant, which ChrisB explained here:

https://ls1tech.com/forums/showpost....6&postcount=83

I'm still looking for how you arrived at 6155274.2 as a constant. Thanks.

TooManyIDs

I'll have to do some searching to see if you guys covered this, but I'm concerned about the impact of air filter changes on the MAF values.

If all these VE calculations are based on the MAF gm/s value, which itself is derived from the value in the MAF table associated with a given MAF frequency, then it is critical to have a MAF table that matches your air filter characteristics, right?

The cars I've been playing with all have VRam intakes, but I haven't made any MAF table changes to match the cold air filter. I guess that was taboo a while back, but seems to me that it has to be addressed.

I'm also still wondering how it impacted the gms/cyl calculation for the timing table, see this thread:

https://ls1tech.com/forums/pcm-diagnostics-tuning/238860-abnormal-timing-values.html

randt

After reading and bit of confusion...What is the 'general consensous'?
I'm trying to decipher and adapt to other formats...
Harley-Davidson applications and also a MegaSquirt converted VW Beetle

Bink

The MAF may NOT be perfect but it will get you close - regardless of air intake type ( gojo has a VaraRam and his VE calcs have been very good). You can then use a Wideband and Commanded AFR to evaluate your MAF - Open Loop or SD.

For Timing Values see the EFILive Forums -> Inside the "FlashScan" Forum GMPX has a Thread on "The Importance of a Good Scanner" (or something like that?) ...he discusses the final timing values we see and how the PCM arrives at them.
T
here are some new PIDS for pulling the various Timing "Adders" and "Subtracters" together for the Final Scanned value we ultimately see.

Hope this helps some.

DVCrazyCamTAWs6

iTrader: (6)

this is the expression i'm using to crack the VE in EFILIVE
({SAE.J1979.MAF} * {SAE.J1979.IAT} / ({SAE.J1979.MAP} * {SAE.J1979.RPM} * 0.0059))

0.0059 = 364ci 6.0L
0.0056 = 346ci 5.7L

Must Set PIDs to : (or will not work)

MAF = UNITS- Grams/Sec, FACTOR - 0.010000, OFFSET - 0 (limits = 0 to 530)
IAT = UNITS- Kelvin, FACTOR - 1, OFFSET - 233.15 (limits = 0 to 500)
MAP = UNITS- BAR, Factor - 0.010000, OFFSET - 0 (limits = 0 to 1.0500)

Expression : (MAF x IAT x / (MAP x RPM x DISPLACEMENT))


After logging i export RPM/MAP/VE Crack, I'm then trying to put together a excel sheet to grab averages from the logged data then have them placed into a excel VE TABLE by MAP KPA / RPM automaticly.. then pasting then new VE table into the editor.. i'm still woking out how to accomplish doing so in Excel. once done this should bring things pretty close to what the car is asking for VE otherwise. hopefully i can come up with a way to make this excel app work, Help!

RedHardSupra

iTrader: (1)

please send me what you got so far, i'm working on a very similar thing. marcinpohl at gmail dot com

Bink

Why not enter your xls files into ChrisB's LS1 Log Analyzer??

Here's a link to info -> https://ls1tech.com/forums/pcm-diagnostics-tuning/98555-new-data-reduction-ls1-edit-automation-software.html

And to the Log File analyzer-> http://www.slowcar.net/analyzer/

Do a search for more info. It works very well.

joel

DVCrazyCamTAWs6

iTrader: (6)

I haven't tried this yet, i'll have to give it a try. still going to see if i can work up an excel app though.

RedHardSupra: i'll send you what i got soon as i figure out why it's not allowing me to use the length of the expression i'm using to to average out RPMs and Map data within a 200 range which would be half of the 400 increasements which is in the table. it might be the version i was using on my laptop haha office 97. going to try the 03 version so if that makes a differnce

DVCrazyCamTAWs6

iTrader: (6)

alright i finished the APP it's 25mbs. you log from efilive , export RPM,Map, and VE crack data. into the excel app. it then in turn makes out a VE table to paste into edit

TooManyIDs

DVCrazyCamTAWs6,
Can you email it? You've created something that will reduce all of the data to values for the appropriate cells? Sounds great, just started wondering how I would do that.

DVCrazyCamTAWs6

iTrader: (6)

yeah it's on my laptop my lady has right now, i'm also goona upload to a server everyone can download from. keep you posted

DVCrazyCamTAWs6

iTrader: (6)

ve crack table edit

Alright there it is. it's my first attemp, so go easy on me. but it works. if you have any question email me ( high10sws6@yahoo.com ) or just post it here..
I'll be working on a more user friendly one with the VE crack built in so you dont have make a new pid for the ve crack in efi live and chang some settings
remember you need to log RPM, map(bar), and the Calculated Ve Crack list below

this is the expression i'm using to crack the VE in EFILIVE
({SAE.J1979.MAF} * {SAE.J1979.IAT} / ({SAE.J1979.MAP} * {SAE.J1979.RPM} * 0.0059))

0.0059 = 364ci 6.0L
0.0056 = 346ci 5.7L

Must Set PIDs to : (or will not work)

MAF = UNITS- Grams/Sec, FACTOR - 0.010000, OFFSET - 0 (limits = 0 to 530)
IAT = UNITS- Kelvin, FACTOR - 1, OFFSET - 233.15 (limits = 0 to 500)
MAP = UNITS- BAR, Factor - 0.010000, OFFSET - 0 (limits = 0 to 1.0500)

~SoL~

TooManyIDs

Thanks for posting. I'll be trying to use this with data logged using EASE.