In this image in my Low RPM Single Fire table, there's rpm vs tps.
The units in the table aren't labeled though. What do they mean?
Does a higher number mean more fuel? Lower means less?
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Admiral Jedi wrote:In this image in my Low RPM Single Fire table, there's rpm vs tps.
The units in the table aren't labeled though. What do they mean?
Does a higher number mean more fuel? Lower means less?
Yes... The value is % VE (Volumetric Efficiency) for that cell.
P&P Tuning
420.5whp / 359.8wtq
In layman's termst this is how I understand it.
Increasing a value in a specific cell will richen AFRs and vice versa.
It represents the amount of air per cylinder by percentage. If you tell the computer there is more air by raising the value, it adds fuel in order to achieve whatever AFR it needs to be at.
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
VE is the percent of volume of ambiant pressure air the cylinder will displace. The higher the number, the more fuel required to achieve a particular Air/Fuel ratio. If the PCM assumes a certain VE, it will add the appropriate fuel to accomidate that condition. Like Ryan said, you already answered your question in layman's terms.... higher number = more fuel, lower number = less fuel.
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OH. I was looking at it the wrong way. I was thinking those values directly affected fuel.
But you're saying the computer makes its own fuel calculations based on the commanded afr and how much air it THINKS is in the combustion chamber based on the tps vs rpm.
I get it now. Is the maximum value 100?
Is that where the VE offset comes in? If my VE offset is 20%. That means I can tune what the ecm thinks is in the combustion chamber up to 20% above the max. So 100 in a cell, with a 0 offset would equal 120 with a 20% offset?
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Random Stuff:http://www.ecotecforum.com/forums/showthread.php?t=6590
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Admiral Jedi wrote:OH. I was looking at it the wrong way. I was thinking those values directly affected fuel.
But you're saying the computer makes its own fuel calculations based on the commanded afr and how much air it THINKS is in the combustion chamber based on the tps vs rpm.
I get it now. Is the maximum value 100?
Is that where the VE offset comes in? If my VE offset is 20%. That means I can tune what the ecm thinks is in the combustion chamber up to 20% above the max. So 100 in a cell, with a 0 offset would equal 120 with a 20% offset?
Your correct, to lean it out you basically make the computer think their is less air than there really is, and vice versa. (The computer has no way of actually measuring the air like in a MAF based system)
Yes, with boost it becomes necessary to raise the offset. If you raise it too much you start to cut off the bottom values of the VE tables. This will cause the car to run like @!#$ on cold start due to being in open loop and running richer than it should (The values in the lower end of the table are forced to a upper maximum - <140% offset equals minimum of 40>
, the problem goes away once it warms up and enters closed loop.
I've started running in to a bit of a problem with this but haven't had time to figure out a work around because I'm currently limited to increasing boost by my injectors.
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
Admiral Jedi wrote:I'm not turboed though, so do I even need to touch the offset?
No, not unless you run out of head room with the current maximum.
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
volumetric efficiency
about the VE offset:
our ecu can only understand a 100% 'spread' of VE.. in other words, if the offset is 0, then the ecu has 0-100%
if the offset is set to 20, then the ecu has 20-120%
if the offset is set to 40, then the ecu has 40-140%
so you have to be careful, because as boost pressure is increased, the ecu loses low-end drivability.
on the stock map, the lowest VE value is 48, so you can set the offset to as high as 40% before noticing any problems
the only thing is changing the offset automatically raises all the values on the VE tables, so you'd have to manually go back and subtract the increase you applied from all the tables.
to tune a supercharger, I would alter the spark tables slightly since you're dealing with forced induction (starting in the LO PE table, I'd copy the 100kpa values over the 105kpa values, and copy the LO PE table over the HO PE table to bring overall timing down when in PE. Leave the other two spark tables alone).
set PE delay RPM to ZERO. especially with the blower, you don't want PE to be delayed when you have the bypass valve closed and boost hitting the engine. There's an explanation of how PE delay works in this forum (my ecu myth thread), and that alone will explain why you don't want PE delayed EVER.. especially with the "instant boost" of a roots supercharger.
then manually go into both low RPM VE tables, and the high RPM VE table and add percentages of VE based on TPS input to give a rough start for tuning the fuel. (Use your TPS threshold for PE as the basis for this)
use histograms to figure the VE error, then apply to the tables as necessary. keep a watchful eye on your WB02 gauge.. its always better to start rich, then lean it out. slowly. Never make huge changes in the tables either, small increments work best.. and always use smoothing to help keep things smooth. if you don't, you'll notice the tune will feel "spiky".
pj when you say subtract from all ve tables, that means idle too correct?
SO_hardcore wrote:pj when you say subtract from all ve tables, that means idle too correct?
yes... You have to add/subtract from all the VE tables when the modifier is used and or changed...
P&P Tuning
420.5whp / 359.8wtq
ImPhat0260/Cavattack2000 wrote:SO_hardcore wrote:pj when you say subtract from all ve tables, that means idle too correct?
yes... You have to add/subtract from all the VE tables when the modifier is used and or changed...
Can we explain more on this please. I do not understand. I have played with the Ve offset on my own car, and a few others. I have not seen any reason to subtract anything. When I have changed these tables it has adjusted the VE tables. Of course I usually tune everything while changing these fields.
FU Tuning
John Higgins wrote:ImPhat0260/Cavattack2000 wrote:SO_hardcore wrote:pj when you say subtract from all ve tables, that means idle too correct?
yes... You have to add/subtract from all the VE tables when the modifier is used and or changed...
Can we explain more on this please. I do not understand. I have played with the Ve offset on my own car, and a few others. I have not seen any reason to subtract anything. When I have changed these tables it has adjusted the VE tables. Of course I usually tune everything while changing these fields.
Lets assume you have a working tune and your VE tables are currently optimized.
Now you decide you want to increase boost but do not have enough head room to raise the VE numbers in the VE tables high enough to add adequate fuel to keep desired AFRs.
Lets say stock the offset is 120% which means you cannot have any values in VE table over 120 (120 is the Maximum)
So now to allow higher VE values you must raise the offset. You change it to 130% offset
At this point when you do this HPT also raises the values in all the VE tables automatically by this percentage difference.
(This will result in a rich/poor tune if you don't fix it)
To fix this you must set all the VE tables back down to what they were before you changed the offset.
***You do this by subtracting percentage function as PJ described OR save a copy of the tune file before you change the offset, and use the HPT compare function and copy and paste all the values for all VE tables from the file where offset is 120% back into the file where offset is 130%.
Now you can go back into rows you are tuning boost and raise VE values above 120 to lets say 128 or 130 to compensate for additional boost.
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
BlackEco wrote:John Higgins wrote:ImPhat0260/Cavattack2000 wrote:SO_hardcore wrote:pj when you say subtract from all ve tables, that means idle too correct?
yes... You have to add/subtract from all the VE tables when the modifier is used and or changed...
Can we explain more on this please. I do not understand. I have played with the Ve offset on my own car, and a few others. I have not seen any reason to subtract anything. When I have changed these tables it has adjusted the VE tables. Of course I usually tune everything while changing these fields.
Lets assume you have a working tune and your VE tables are currently optimized.
Now you decide you want to increase boost but do not have enough head room to raise the VE numbers in the VE tables high enough to add adequate fuel to keep desired AFRs.
Lets say stock the offset is 120% which means you cannot have any values in VE table over 120 (120 is the Maximum)
So now to allow higher VE values you must raise the offset. You change it to 130% offset
At this point when you do this HPT also raises the values in all the VE tables automatically by this percentage difference.
(This will result in a rich/poor tune if you don't fix it)
To fix this you must set all the VE tables back down to what they were before you changed the offset.
***You do this by subtracting percentage function as PJ described OR save a copy of the tune file before you change the offset, and use the HPT compare function and copy and paste all the values for all VE tables from the file where offset is 120% back into the file where offset is 130%.
Now you can go back into rows you are tuning boost and raise VE values above 120 to lets say 128 or 130 to compensate for additional boost.
Thanks for explaining. I will have to play with this more. Usually when I have moved VE offset I have retuned all files anyways, so I should be good. I also have played with this and it only raises the cells that were already higher, not all cells. I will play some more.
FU Tuning
Wow, I just played with this. I never realized it. Thanks for teaching me something.
FU Tuning
John Higgins wrote:BlackEco wrote:John Higgins wrote:ImPhat0260/Cavattack2000 wrote:SO_hardcore wrote:pj when you say subtract from all ve tables, that means idle too correct?
yes... You have to add/subtract from all the VE tables when the modifier is used and or changed...
Can we explain more on this please. I do not understand. I have played with the Ve offset on my own car, and a few others. I have not seen any reason to subtract anything. When I have changed these tables it has adjusted the VE tables. Of course I usually tune everything while changing these fields.
Lets assume you have a working tune and your VE tables are currently optimized.
Now you decide you want to increase boost but do not have enough head room to raise the VE numbers in the VE tables high enough to add adequate fuel to keep desired AFRs.
Lets say stock the offset is 120% which means you cannot have any values in VE table over 120 (120 is the Maximum)
So now to allow higher VE values you must raise the offset. You change it to 130% offset
At this point when you do this HPT also raises the values in all the VE tables automatically by this percentage difference.
(This will result in a rich/poor tune if you don't fix it)
To fix this you must set all the VE tables back down to what they were before you changed the offset.
***You do this by subtracting percentage function as PJ described OR save a copy of the tune file before you change the offset, and use the HPT compare function and copy and paste all the values for all VE tables from the file where offset is 120% back into the file where offset is 130%.
Now you can go back into rows you are tuning boost and raise VE values above 120 to lets say 128 or 130 to compensate for additional boost.
Thanks for explaining. I will have to play with this more. Usually when I have moved VE offset I have retuned all files anyways, so I should be good. I also have played with this and it only raises the cells that were already higher, not all cells. I will play some more.
Edit : Where I said 120/130 % I actually meant offset of 20/30%
Also keep in mind by correcting the values in the VE tables after changing the VE offset you are creating a lot less work for yourself when it comes time to do VE tuning via the Histograms like in theFAQ because you are starting with less % in error in more cells (assuming you are running correct injector constant at stock fuel pressure.)
___________________________________________________________________
Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
Quote:
Edit : Where I said 120/130 % I actually meant offset of 20/30%
Also keep in mind by correcting the values in the VE tables after changing the VE offset you are creating a lot less work for yourself when it comes time to do VE tuning via the Histograms like in theFAQ because you are starting with less % in error in more cells (assuming you are running correct injector constant at stock fuel pressure.)
I knew what you meant on the off set. I also understand the less tuning time, makes total sense. thanks again.
FU Tuning
I honestly think a lot of people overlook this....
P&P Tuning
420.5whp / 359.8wtq
ImPhat0260/Cavattack2000 wrote:I honestly think a lot of people overlook this....
I think your right. In most cases I have always retuned after adjusting VE offset, but one car I had some issues with going from idle to moving, I think I now why now.
FU Tuning
