Has anyone bothered to pay around with this any? Such as using it as a Global fuel trim instead of an absolute real value??
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I have. Does not seem to be practical, but limited time was spent. The problem I always see with tables like this, and you know this but for the people who don't, is they are way outside the range of a factory 02 sensor. So how are they calculating the a/f? Once again as you know, it's a complicated equation using some static variables. Problem with that of course is if you change something, like a turbo, the PCM has no fing idea what the a/f ratio it. Does not mean it could not be used, a multiplyer is a multiplyer no matter what it does, I have just found that VE or Power enrichment above stoich has achieved my goals quicker and easier.
So did you finally dive in and buy the PRP? I am curious to hear your thoughts on this table.
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That's one of the first things I changed. Then I did ALLOT of datalogging so that I could tune My VE table correctly(2.0 cams w adj gears). My idle and cruizing is 14.75 rock solid and my fuel trims never very more than +-3. Full Throttle enrichment numbers are right on too. It does take alot of time, patience, and math, but if I want to change my FTE I can just calculate the difference and put it in and have it right the first time. The VE table is the worst part of it all.
That's one of the first things I changed. Then I did ALLOT of datalogging so that I could tune My VE table correctly(2.0 cams w adj gears). My idle and cruizing is 14.75 rock solid and my fuel trims never very more than +-3. Full Throttle enrichment numbers are right on too. It does take alot of time, patience, and math, but if I want to change my FTE I can just calculate the difference and put it in and have it right the first time. The VE table is the worst part of it all.
Interesting,,, So for your tuning stategy: once the VE was set to better match the cams you left it? and you make all other F/A changes via FTE and Stioch then??
Anyway,
I was thinking one could bump the F/A to around 15-16:1 gain a bit of mpg and then modify the FTE to correct WOT A/F.
Interesting,,, So for your tuning stategy: once the VE was set to better match the cams you left it? and you make all other F/A changes via FTE and Stioch then??
Anyway,
I was thinking one could bump the F/A to around 15-16:1 gain a bit of mpg and then modify the FTE to correct WOT A/F.
You are correct. I set my stoich, then my VE table, and then the FTE table. It's a PITA to get the VE table correct but once you have that the FTE is easy as pie. You calculate what you need on top of the 14.75 or whatever and then put it in the table. Blamo!!! you have the f/a ratio you want. I've thought about making another tune where my target f/a is set higher but I'm still running the stock snail and I don't wanna raise my egt's anymore than they already are. Maybe one day I'll pony up for a bigger turbo.
You are correct. I set my stoich, then my VE table, and then the FTE table. It's a PITA to get the VE table correct but once you have that the FTE is easy as pie. You calculate what you need on top of the 14.75 or whatever and then put it in the table. Blamo!!! you have the f/a ratio you want. I've thought about making another tune where my target f/a is set higher but I'm still running the stock snail and I don't wanna raise my egt's anymore than they already are. Maybe one day I'll pony up for a bigger turbo.
Thats what I thought Mopar would have done too. But if you look at the Stock, S1 and S2 VE table,,they're all different. Go figure? Same head, cams, intake, exhaust and turbo, but different VE?? Its not likely the actual VE changes but none-the-less the tables are different.
I don't know why "Mother Mopar" would change it but her engineers are way smarter than me. It works great for me cause I can create different fuel maps quickly by just changing the FTE map(power enrichment map).
Last edited by sour kraut : 05-12-2008 at 01:23 PM.
You are correct. I set my stoich, then my VE table, and then the FTE table. It's a PITA to get the VE table correct but once you have that the FTE is easy as pie. You calculate what you need on top of the 14.75 or whatever and then put it in the table. Blamo!!! you have the f/a ratio you want. I've thought about making another tune where my target f/a is set higher but I'm still running the stock snail and I don't wanna raise my egt's anymore than they already are. Maybe one day I'll pony up for a bigger turbo.
lots of datalogging!!!! I cheated. Using the extended chrysler datalogger from autoinginuity I log my rpm, pressure ratio, total amount of fuel injected for cylinder 1, raw tps voltage and raw secondary o2 sensor voltage. I disconected the signal from my secondary and connected my wideband to it for datalogging purposes. Not all widebands are created equal so be careful, the 2.5 volt reference on the line may damage something in your wideband. it didn't on mine(dynojet WB commander). This allowed all the information I needed to be in one datalog. After creating many many logs and using a hand calculator to do the math for about 3 hours, I ended up writing code for a small calculator that did all the math to calculate the actual ve and then group and average them per cell ranges defined in a spread sheet. Pretty easy huh?
If the above scares you or you don't have access to an extended logger, use the fuel trims. This can get you farely close but you're still going to need to do allot of math to get it right the first (or second) time.
If the above scares you or you don't have access to an extended logger, use the fuel trims. This can get you farely close but you're still going to need to do allot of math to get it right the first (or second) time.
Not scary--just involved. No logger yet either since i'm not sure which one to get. The AE set up is $400 on their site, and the link to extended specific sensors doesn't work--do you get knock with that too? Overall do you like it? I may just get a wideband and wait and see if SCT livewire comes through.
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F/A Stoich ??
Linear Mode
