1slowbusa

iTrader: (8)

Today I performed some tweeking to smooth my VE table during part throttle and this is the outcome. I am withing +/-5% on my LTFT. There is a difference, the throttle is much smoother.

danieloneil01

Post your tune

subeone

iTrader: (5)

i dont recommend tuning via ltft..

that VE table doesnt look near done

try making it look like this in terms of progression throughout the lower rpms:

1slowbusa

iTrader: (8)

Yes, I know the tune isnt complete, I only get so much seat time due to work and school. Today I had a couple of free hours so I spent them on the car.

Why do you not like tuning via ltft? I am doing the learn at home from The Tuning School and that is how they teach for normal driving, with a wideband during WOT.

danieloneil01

Everyone has their own ways to skin a cat. Most tune WOT by AFR error % compared to a wideband. Don't know to many that tune WOT using LTFTs. LTFTs will want to add fuel when you go into PE mode to get it back to stoich. If you won't post your tune, then show your VE table as a 2D chart. Some tune part throttle with STFTs or the same way as they do WOT, AFR error %.

This is a bad tune


This is better. WOT is dead on but I want the part throttle to be dead on when my IATs aren't 110*+. When they are above 110*, CL is the ticket.

1slowbusa

iTrader: (8)

Here is the tune and a 2D snap shot of the primary VE table. Please note that the tune is a base tune that I was working on remotly with a well known tuner, but never finished. I have sense purchased the learn at home from the Tuning School and have been tuning the car myself eversense.

As far a tuning WOT, I do use AFR % error and I have an AFX NGK wideband. I do not use LTFT to tune WOT.

As far as tuning normal driving, I am using the LTFT. My LTFT are within +/-5% in my cruising range. Of course, I understand that there is still alot more tweeking to be performed but really need to find the time to do it.

The car is a 2000 Camaro SS M6 LS1
AFR 205 62cc heads, Polluter V2 Cam, Fast 102 intake and NW throttle body fast toys 104 lid, FIC 42# injectors and many more supporting mods.

Hope this helps, please provide any feedback that is necessary because I am always open to learning something new.

subeone

iTrader: (5)

tune your VE table using that wideband you have with the AFR error pid and in open loop., tune not just wot, but part throttle and steady state as well. Once you have verified that your afr error is +- 2% then you know damn well that the airflow table is right because you verified with a wideband. Once you put your car back into closed loop and your stft/ltft's are +-5 or more then you know your oxygen sensors are crap and are actually hurting your need to tune your car. So that's why its bad to tune with LTFT, STFT in general without a wideband, you can't trust your narrowband sensors. Once again, verify your afr at part throttle and WOT that you get an afr error of +-2 percent while on open loop, then put it back in closed loop, if your fuel trims are higher than your AFR error, then you know you can't trust the fuel trims because you verified with a wideband that whatever changes you did to the airflow table, were proper.

sorry for the long reply

soundengineer

iTrader: (16)

your VE table is Just fine....
while the lowe regions could probably use some work... the rest looks pretty normal

most people cannot get good data at low kpa and low rpm...its just not possible with the slow o2 sensors we purchase for a couple of hundred bucks..

one thing you can do to get it closer in the lower sections, is to change the cell hits it takes to register....then spend more time tuning that area.
change cell hits to 50 or 100 counts before it registers....
it will take quite some time to get data in those areas... but atleast its going to be a large sample set to get a better value

remember, this is in Volumetric efficiency, not in actual fuel needed...
volumetric efficiency can be higher in low areas in some cases
in general the engine trend will be less VE in lower kpa and RPM, and higher VE at higher kpa and higher rpm


2% is pointless...you will see more swing than that from one day to the next....and good luck getting any accuracy within 2% on any narrowband...
if you are within 5%, you are close enough.

if you tune with a wideband, and can view the narrow band as well....
you can see if it crosses at approximately 14.7 AFR on average(its not going to do it every time)... if it does cross 14.7 ish or pretty close to it... your narrow band's are valid...the way narrowbands work is they are only accurate at stoich 1.0 values...doesnt care what fuel you use, its only going to cross at 1.0...
also remember... any gas with Ethanol in it will read richer(10% ethanol will bring it down to 14.2/14.3 ish)...so you may need to buy a tester and measure the ethanol content in your gas before you start this test.

subeone

iTrader: (5)

Im telling him to get the ve table as close as possible and see if his o2's are doing the same thing, if they arent right at that instant then the narrowbands can't be trusted to tune part throttle..
yes I know oxygen sensors measure oxygen content, so 1.0 will always be the stoich for any hydrocarbon, the display on most widebands are setup to transform the lambda value into an afr number we are familiar with.

I would reset your fuel trims 1st then tune off of those if I would tune with ltft @ op

1slowbusa

iTrader: (8)

First off I want to thank both of you for your comments. I was able to take your comments/suggestions and learn from them.

I found time today to do some tuning and this is what I got. Anything under 50kpa and up to 1200 rpm I could not record. The car just doesnt run in that range so I just manually smoothed that area.

I recorded both my LTFT and AFR Error and they are very, very close to one another. I attached a couple of snap shots for you guys to see. This tells me that my narrowbands are working properly compared to my wideband.

I spent a lot of time trying to smooth my VE table with the 2D chart and found it to be much easier to understand that way. I also went to the HP tuner forum Repository and started looking around at other VE tables and they are very smooth just like you guys said.

The car does run a lot smoother but I did run out of time but made a lot of progress in my opinion. Take a look and let me know your thoughts.

thanks again! & I know I still have a long way to go.

subeone

iTrader: (5)

the table looks much more consistent now

soundengineer

iTrader: (16)

you cant use the VE table and compare Fuel trims to AFR..... it doesn work that way....
Fuel Trims are based on a Fuel Trim Cell... not VE cells...
the only way you can compare them is to look at them in the scanner in the Line plots, or to make a custom Histogram of AFR vs O2 sensor


so you tune by AFR, then look to see if your O2's are switching around stoic... they arent going to be exact..they are influenced by heat and need a certain heat range to be exact.

if they dont match up, then you have 3 options.. fine tune the switch values in the tune, relocate the O2's or buy different o2's and hope they have a better heater...


if they do match up switch points to AFR for stoic on your current fuel, then you need to fine tune your Fuel trim cell divider values to get it to be in a reasonably close approximation of your wideband...and probably revisit the VE /MAF tables again with your wideband to fine tune them some more

no matter what, you will get Fuel trims, plus and Minus....all the time....no way around it...and its what your car is supposed to do to control the needed changes in fueling from day to day.