VE tables VS STFT+ LTFT

[pezfighter99]

I have a 6.1L Challenger with a manual trans and a Whipple supercharger kit. Otherwise, the engine and exhaust are stock. The STFT+LTFT values for both banks are quite negative (mostly double digits). Neural Network is DISABLED in the supplied tune which is OK by me. I've read that the fuel trims can be adjusted by altering the VE tables BUT I can't find the info on whether increasing or decreasing the VE value in a cell will cause the STFT+LTFT to be less negative (closer to zero). Some help would be appreciated.

[N2speed]

The 6.1 Never used NN. Its in the table but disabled. You need to data log and use that data to adjust the VE Table.
I offer remote tuning if that is something that you are interested in and specialize in Dodge.

[pezfighter99]

Thanks for your reply. I guess that I wasn't very clear in my original post. I've read IN THIS FORUM that the VE tables can be used to adjust the STFT+LTFT when the Neural Network is disabled. I've simply forgotten what effect increasing OR decreasing the values in the VE tables has on the STFT+LTFT. I can't find the right post where I read it originally. I'm NOT looking for remote tuning, I'd just REALLY appreciate an answer to my original question. The STFT+LTST vs Pressure Ratio values, from the HP Scanner, for both banks are very negative (approximately -10 to -30). To get (increase) the negative STFT+LTFT values to be closer to ZERO, should the values in the VE tables be increased or decreased?????????. SOMEONE, PLEASE ANSWER MY QUESTION!!! I'm tired of searching this forum for the answer I read previously. THANK YOU!!!

[f.creek-ranch]

higher values means more power = more fuel.

why dont you use the inj pulsewith vs fuel mass to correct the fuel trims ?
the correct way is to dial in the injectors first.
U can set the fuel mass data (g) in the row axis higher or change the values to get closer to your closed loop operating range from the injectors.

[pezfighter99]

F.creek-ranch, thanks for the reply.

Reading an older post, I was led to believe that inj pulsewidth vs fuel mass was to be used when the Neural Network was ENABLED. Since my Neural Network is DISABLED , the VE tables must be used to adjust stft+ltft. Was the older post wrong???

[f.creek-ranch]

there must be injector data. how should it work without a scaling ?

[Dave401Redeye]

F.creek-ranch, thanks for the reply.

Reading an older post, I was led to believe that inj pulsewidth vs fuel mass was to be used when the Neural Network was ENABLED. Since my Neural Network is DISABLED , the VE tables must be used to adjust stft+ltft. Was the older post wrong???

I think you are asking and answering your question correctly. If you are successful in getting a clean log. You copy the trim cells with axis. then go to your ve table and paste them in. After you right click your log and copy with axis you collected using vcm scanner. Click over to vcm editor and oped your ve tables for bank 1 and bank 2. right click on either bank. hover over "paste special" another row of choices will open, if you click on multiply by % it will add the whole number. -30 will add 30 to your ve table. It is better to choose multiply by 50% so you dont keep over correcting. -30 will add 15 to the ve. When you are done with one bank. Just copy and paste it to the other banks ve table.

To log fuel trims you have to turn off anything that will add fuel. PE tables need to be zeroed out. You can turn off decel fuel by rasing the temp to a value it will never reach to activate it. 376 is usually a easy number to reconize when looking to turn them back on. Remember when pe is zeroed out dont run the enging at wot because it will be extremly lean as soon as boost starts to build.

I can log STFT average vs pressure ratio then in another graph i can log LTFT vs pressure and get a populated graph. When i log LTFT + STFT vs pressure ratio it only populates the top row across as rpm goes up. Not sure why i have this issue. But if you do try logging STFT and LTFT on seperate graphs.

[f.creek-ranch]

I had have the same problem in Vcm Scanner.
sometimes it have log only the top row.
after I ve updated to another beta version it works correctly again.
To log VE table you can set the whole PE table to get an AFR of 12,5 i.e.
so you can get in WOT without issues and log all data. The WOT from pedal to 0V will keep you in OL.
Amazing how it reacts to pedal in OL….

[pezfighter99]

TO: Dave401Redeye - I tried your method of "In the Scanner, copy the trim cells with axis" and then going to the Editor and after right-clicking over the VE table and selecting "multiply by 50%". The result SUBTRACTED 50% from all the VE values and didn't ADD like you posted it would. All the values in my STFT+LTFT graphs are negative (approx. -10 to -30). NOW I'm confused again. IF my STFT+LTFT values are NEGATIVE numbers, should the VE table numbers be added too OR subtracted from their original values?????????

PLEASE RESPOND!!!

[Rob2014]

Pezfighter99 you are correct,
if your log is say -30 and you copy and multiply by half it will lower that ve cell by -15%. The Ve table is just chart for fueling , and the number ( percentage %) in that cell is saying how much air ( or how full of air in %) is in your cylinders at that rpm and p-ratio / load. So base on that number or % the pcm tells the injectors how much fuel to spray to get the stoich afr. So (assuming your injector data is correct) if logging -30 in that cell that means you are getting 30% to much fuel over stoich afr (or f.a.r as Dodge like to use). That means that the cell on the ve table is 30% to high and is not that full of air at that time. You would normally only need to ajust ve table if you add a mod that changes air flow in your Eng like a cam, pully swap , ported sc, turbo ect. I hope this help clear it up for you if you haven?t already figured it out.

[Rob2014]

Also, you would get alot of negative numbers if you did a injector change to bigger so it put more fuel in. If that?s the case then you would make the car Stay in open loop and log stft+ltft error. and the x row, log fuel grams exactly the same way it is in your injector data in fuel mass vs pulse width ( copy fuel mass from tune and paste in x row in scanner ) . Then you take them +\- percent number copy in scanner and past and multiplied by Half in your pw data in tune to rescale / recalibrate you injector data . Just remember once you do that you then have to make sure the numbers match in pw versus fuel mass , so you will have to ajust them every time you ajust after logging until they are dialed in. It just determines on what you?ve done and changes to determine whether you need to adjust VE tables or injector info ? depending on whether you change your air or fuel with your mod.

Good luck!!!!

[skala308]

Pezfighter99 you are correct,
if your log is say -30 and you copy and multiply by half it will lower that ve cell by -15%. The Ve table is just chart for fueling , and the number ( percentage %) in that cell is saying how much air ( or how full of air in %) is in your cylinders at that rpm and p-ratio / load. So base on that number or % the pcm tells the injectors how much fuel to spray to get the stoich afr. So (assuming your injector data is correct) if logging -30 in that cell that means you are getting 30% to much fuel over stoich afr (or f.a.r as Dodge like to use). That means that the cell on the ve table is 30% to high and is not that full of air at that time. You would normally only need to ajust ve table if you add a mod that changes air flow in your Eng like a cam, pully swap , ported sc, turbo ect. I hope this help clear it up for you if you haven?t already figured it out.

Rob2014, you explained this very well, thanks.
I helps when new members are given clear understandable answers.
By the way, I fully agree with your explanation.

[troyclayton337]

Pezfighter can you share the base tune that you got from whipple? Shouldn?t they have adjusted the fuel injector data if they supplied with your kit? I?m prepping a hellcat supercharger for an otherwise stock 6.1L and would be interested in seeing how whipple changes the tune.
Thank you

[pezfighter99]

THANK YOU ALL FOR RESPONDING!!! Yes, I'm fairly "green" at this electronic tuning crapola. Carburetors I know. Dealt with them for years. Rebuilt so many I've lost count. I even rebuilt a Six Pack off a 1970 440 Road runner. You used to have to be able to read spark-plug color and use a vacuum gauge to set the idle and actually LISTEN for engine detonation to adjust timing for the gas and setup you were running.

Chrysler's way of engine control is bass-awkward. Torque comes from the amount of air an engine can ingest. If you want more torque, you either increase displacement, add a power adder (turbo or supercharger) or increase the flow potential of the engine thru cam, head, intake of exhaust mods. YOU DON'T figure the amount of torque an engine of a given size and air flow potential could possibly produce and then back calculate everything to come close to it with fuel-air mix. I'd guess their way of doing things goes back to their affiliation with Dailmer-Benz. The Europeans have a different mind set than us. If for no other reason than to be contrary to us Yankees.

PLEASE EXCUSE MY RANT!!!

For "troyclayton337" I'm attaching 3 tunes. Stock SRT 6.1L, Whipples tune they supplied and my latest rendition which helped drive-ability and my initial VE mods.

[pezfighter99]

BACK TO REALITY - While I don't have any incite on adapting a Hellcat SC to a stock 6.1L, I can give a few observations about the Whipple tune I attached earlier.

Due to Whipple's long supercharger history, I expected them to have all the kinks worked out. The SC kit was well designed and outside of some missing hardware and a couple of "goofs" in the install manual, it all went together as it was meant to. The INITIAL tune they supplied was FLAWED, at least from my perspective.

The car (2009 SRT 6 speed) was almost undriveable. The throttle was SO sensitive and I can drive almost anything. They sent me a second tune that was dumbed down so much that the car was very lazy despite having a SC. I bought a HPTuner kit and after reading MANY posts in this forum, I was able to get the throttle reasonable. Then there was the "light-switch" effect where slowly giving more pedal gave the all of a sudden "YEE-HA!!!" we're moving now. Again with reading old posts, I was able to tone that down some. I think the member HEMITUNA is overly optimistic about completely eliminating the light-switch thing.

Trying to tone down the light-switch thing, I started using the HPScanner and found out that the fuel trims were WAY negative. Gave me something else to futz around with. I'm REALLY disappointed with Whipple's tune.

Just for a point of reference, the Whipple kit uses stock injectors with a MSD Fuel Pump Booster which increases voltage to the stock fuel pump when under boost to increase fuel pressure.