how "smooth" should a VE table look like?
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From: CroSSby, TexaSS
how "smooth" should a VE table look like? After 3-4 days of datalogging and multiplying my afr error % by Half over to my VE table and smoothing i am getting nowhere, it looks nothing like my dyno tune VE table 3D chart. anyone got some pictures of what it should look like? I'd love to fix my 11mpg
Also, I'm in SD open loop..
Also, I'm in SD open loop..
I really don't like that method at all, the paste-histo scheme.
You know what they say about statistics.
A histogram can get really full of transient garbage and make
the data worse than useless if you're street tuning. You want
to be more selective about what you believe.
I can't get past doing it by hand, based on segments of logs
that I select for being steady conditions and stable WBO2
readings.
In the end the motor is a fairly regular air pump and should
have no abrupt discontinuities. If you've got a porcupine
VE table, that's showing you the truth of "garbage in,
garbage out".
You know what they say about statistics.
A histogram can get really full of transient garbage and make
the data worse than useless if you're street tuning. You want
to be more selective about what you believe.
I can't get past doing it by hand, based on segments of logs
that I select for being steady conditions and stable WBO2
readings.
In the end the motor is a fairly regular air pump and should
have no abrupt discontinuities. If you've got a porcupine
VE table, that's showing you the truth of "garbage in,
garbage out".
Thread Starter
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From: CroSSby, TexaSS
I really don't like that method at all, the paste-histo scheme.
You know what they say about statistics.
A histogram can get really full of transient garbage and make
the data worse than useless if you're street tuning. You want
to be more selective about what you believe.
I can't get past doing it by hand, based on segments of logs
that I select for being steady conditions and stable WBO2
readings.
In the end the motor is a fairly regular air pump and should
have no abrupt discontinuities. If you've got a porcupine
VE table, that's showing you the truth of "garbage in,
garbage out".
You know what they say about statistics.
A histogram can get really full of transient garbage and make
the data worse than useless if you're street tuning. You want
to be more selective about what you believe.
I can't get past doing it by hand, based on segments of logs
that I select for being steady conditions and stable WBO2
readings.
In the end the motor is a fairly regular air pump and should
have no abrupt discontinuities. If you've got a porcupine
VE table, that's showing you the truth of "garbage in,
garbage out".
I agree it shouldn't have huge spikes, or valleys but being perfectly smooth i believe is not the case either, I've seen many many files and tunes including files from factory Gm especially in corvette, where the table are no way smooth so to me not uncommon to see waves in the table.
First, are you sure the MAF is failed? I've been caught that way more than once.
The dyno VE table you speak of, was it on a load bearing dyno hitting those specific cruise cells.
LTFT's on or off?
I'm not one of those you have to tune in OL unless you are going leave OL. If you are going to run CL why not tune that with your STFT's. If there is big difference's between OL & CL of course that needs to be addressed.
Your street tuning the VE obviously, how are you collecting the data in those cells?
The dyno VE table you speak of, was it on a load bearing dyno hitting those specific cruise cells.
LTFT's on or off?
I'm not one of those you have to tune in OL unless you are going leave OL. If you are going to run CL why not tune that with your STFT's. If there is big difference's between OL & CL of course that needs to be addressed.
Your street tuning the VE obviously, how are you collecting the data in those cells?
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FormerVendor
Joined: Nov 2012
Posts: 390
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From: Dyno Tuning in KY
First off its a good idea to tune in open loop pending you have a quality wideband... I've seen instances more than not that the narrowband sensors don't target exactly stoich and the setpoints themselves need adjusted to accurately target stoich after modifications have been made. Most of those cases are larger cam setups with plentiful overlap.
Steady state is required to adjust VE accurately. This is where a loaded dyno to hold the engine at a steady rpm while varying load and adjusting the table is the most precise way of doing it.
Now on to your question does it have to be smooth? Smooth is normally the result of what the engine wants. Don't smooth the table to make it "look" good, adjust the table to what it wants. Once finished you will see a trend of smooth contour from low load to high load. Some camshaft intake and header configurations will cause a certain rpm to drop VE or raise VE. The most notable occurence I can think of is 5.3l trucks. They generally want a ridge or ditch all the way up the (if memory serves) 1600rpm column. Smooth that out to the 1200 and 2000 column and you get excessive rich condition. So in the end give the engine what it wants. The only thing I know that should be smooth is up the load point. You are not going to flow more air at 50kpa @2000rpm than you do at 55kpa @2000rpm. So keep that in mind when building a VE table.
Steady state is required to adjust VE accurately. This is where a loaded dyno to hold the engine at a steady rpm while varying load and adjusting the table is the most precise way of doing it.
Now on to your question does it have to be smooth? Smooth is normally the result of what the engine wants. Don't smooth the table to make it "look" good, adjust the table to what it wants. Once finished you will see a trend of smooth contour from low load to high load. Some camshaft intake and header configurations will cause a certain rpm to drop VE or raise VE. The most notable occurence I can think of is 5.3l trucks. They generally want a ridge or ditch all the way up the (if memory serves) 1600rpm column. Smooth that out to the 1200 and 2000 column and you get excessive rich condition. So in the end give the engine what it wants. The only thing I know that should be smooth is up the load point. You are not going to flow more air at 50kpa @2000rpm than you do at 55kpa @2000rpm. So keep that in mind when building a VE table.
Last edited by James@ShorTuning; Jan 31, 2013 at 10:41 PM.
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From: CroSSby, TexaSS
Like I said, I've only just started messing with the WOT part of the table. Both logs are from this same tune file, MAF is set to fail as well. If there is an error that I could have made please inform me, I'm trying to get past this hurdle. With the Dyno tune the car had, it gets horrible mpg, the injector data was all sorts of wrong and AFR bounces all over the place while cruising..(13.0-15.0) with my SDOL tuning attempts I can get a solid constant AFR number.
Also, i run a PLX AFR gen 2 wideband with the bosch 14.2 sensor
Also, i run a PLX AFR gen 2 wideband with the bosch 14.2 sensor
Last edited by greenvortec97; Jan 27, 2013 at 11:17 AM.
FormerVendor
Joined: Nov 2012
Posts: 390
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From: Dyno Tuning in KY
Ill check it out when I get home tonight. When you do cruise down the highway try to keep your rpm as close to the column rpms as possible. Filter out throttle transients when you make adjustments. It takes longer but quality data is needed to accurately dial in the VE.
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From: CroSSby, TexaSS
Ill check it out when I get home tonight. When you do cruise down the highway try to keep your rpm as close to the column rpms as possible. Filter out throttle transients when you make adjustments. It takes longer but quality data is needed to accurately dial in the VE.
FormerVendor
Joined: Dec 2001
Posts: 2,444
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From: WWW.SPEEDINC.COM
I really don't like that method at all, the paste-histo scheme.
You know what they say about statistics.
A histogram can get really full of transient garbage and make
the data worse than useless if you're street tuning. You want
to be more selective about what you believe.
I can't get past doing it by hand, based on segments of logs
that I select for being steady conditions and stable WBO2
readings.
In the end the motor is a fairly regular air pump and should
have no abrupt discontinuities. If you've got a porcupine
VE table, that's showing you the truth of "garbage in,
garbage out".
You know what they say about statistics.
A histogram can get really full of transient garbage and make
the data worse than useless if you're street tuning. You want
to be more selective about what you believe.
I can't get past doing it by hand, based on segments of logs
that I select for being steady conditions and stable WBO2
readings.
In the end the motor is a fairly regular air pump and should
have no abrupt discontinuities. If you've got a porcupine
VE table, that's showing you the truth of "garbage in,
garbage out".
Once I get WOT to equal commanded AFR and everything closed loop to within a few percent of zero on the fuel trims it is finished.
This is what a typical mild naturally aspirated setup ends up looking like-
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From: CroSSby, TexaSS
I agree and have seen plenty of VE tables that make no sense at all. I manipulate the brake on the dyno to go as near to steady state in each cell I can get to then use those trends to build the VE table which I blend by hand.
Once I get WOT to equal commanded AFR and everything closed loop to within a few percent of zero on the fuel trims it is finished.
This is what a typical mild naturally aspirated setup ends up looking like-
Once I get WOT to equal commanded AFR and everything closed loop to within a few percent of zero on the fuel trims it is finished.
This is what a typical mild naturally aspirated setup ends up looking like-
FormerVendor
Joined: Dec 2001
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From: WWW.SPEEDINC.COM
Here's an example. This car was tuned by a local shop and came in with this-
-And left with this, part throttle air fuel perfect, WOT a/f ratio exactly matching commanded at every boost level and correct transients. You won't accomplish that with huge dips and holes in the table. It just has to make sense.
