I remember one time when I was a teenager me & a good friend decided to enroll in a martial arts program for the hell of it. That lasted with me for about 6-8 months then I moved on. My friend became lost in it, he lived it, ate it, & breathed it. I never saw him after that.

I have become lost in this tuning ordeal. For the longest I have been tuning my fuel by using IFR rates & PE vs. RPM tables. This has always worked well. After doing some tedious logging I noticed some fuel problems with this new cam (224/224 .589 114 lsa).

I have figured out that this was in large part due to my maf & map rates thrown way off with the oversized cam. I have now decided to bite the bullit & do a nasty tune rescaling maf's & using the ve tables.

I have ran into a few questions though & I am hoping one of the truck guys could give some insight.

when using ve tables are you applying the ve formula based off logged data? VE= {massflow * IAT/ (MAP * RPM * DISPLACEMENT}
THEN APPLY THE MATH TO THE BOXES?

OR

ARE YOU RESCALING THE VE TABLES BY PERCENTAGES BASED OFF THE FUEL DATA?

I HAVE PARTIALLY DONE THIS ALREADY PRETTY MUCH JUST LOGGING & DOING THE MATH & PLUGGING IN THE NUMBERS. IT HAS MADE A TON OF DIFFERENCE IN THROTTLE RESPONSE!THIS WOULD TAKE ME EONS TO DO LIKE THIS.

I started to build a spread sheet, I just got confused on plugging in the math....

IF i CANNOT RESOLVE THIS SOON I AM MOVING TO TIBET FOR 7 YEARS.

WHO HAS TUNED USING THIS METHOD? PLEASE GIVE NASTY SECRETS.......

THANKS IN ADVANCE...... BLAKE

 

Hey Blake - I can't say I'm a big dog or anything, but I've done a 'first round' speed density tune on my truck. Is that basically what you're asking about here?

What tuning software are you using?

I'm using HTP v1.6, which makes SD tuning and VE modifying a BREEZE.

First off, to accurately use your fueling data to modify your VE table, you MUST disable the MAF. I just want to verify that you did that...?

Once that is done, it forces the PCM to run off of the VE table alone (unless you go WOT and into PE mode - so don't go WOT, or disable PE by filling the table with 1's). The fueling data you scan, will now be directly related to the VE table.

If you don't do that, you'll still get data that looks like it will work, but it's "masked" by the MAF's output - which will need tuning later on when everthing with the VE table is done with.

I rescaled my VE table with about three logging sessions of fuel trim data. My first one I used my LTFT's and STFT's, which DID require a little bit of math. That math is located in the help file in the HPT "how to" section that's included with the software. (do you have HPT?)

The next to rounds, I disabled LTFT (by raising the Long Term Fuel Trim Enable coolant temp to like, 285*F.) What data you log in the STFT histogram, can be added DIRECTLY over your VE table with a simple copy and paste. If things look nasty, (bumpy, jagged), hit the "Smoothing" button ONCE.

I'm running a smaller cam in my 6.0L here, and I had to make some rather agressive changes to the lower part of the VE table.

 

I am using edit to tune, how are you disabling your maf? I f I unplug it I am sure it would die. I am assuming you are changing the expected flow rate tables. I have not disabled the maf, I was under the impression that I needed to log & correct these in order to do the ve tune.

I have been logging the varibles for the formula I listed, then sitting down & figuring out the actual ve, then adjusting that individual cell. Doing this I have noticed a crazy difference (seat of the pants @ part throttle)! I now realize I have walked backwards. I do not have a smoothing button to hit either I have been logging with A tech II & replaying. I feel lost now more than ever......WTF!

The problem now is that I will run circles until I get it right. Let's pretend I am a goofy,redneck, goat chasing hillbilly & you lay it out for me. This really sucks to because it is very apparent that there is alot left on the table......

Thanks in advance........

 

Actually it would run with the MAF off and run fine -- the problem is if your truck has a 5 wire MAF, your IAT sensor is built into the MAF. If that's the case, unplugging the MAF == cutting the sending wire (and resoldering or using a quick connect later).

Calculating the VE is a big waste of time, IMO. Just SD tune the VE in place and then plug the MAF back in and tweak it into place. Numerous threads on SD tuning in the PCM forums.

 

I am assuming you are adding a percentage if lean & subtracting a percentage if rich, correct?

So I should just log my map vs rpm vs stft & adjust as needed?

 

i like what these guys are saying. yes just add fuel(biger number) when it shows lean and pull fuel when it shows rich.

are you using efilive? i was given a "majical" formula to enter into efilive where it will completely fill in a table for you. all you have to do is drive around for an hour or so and let it do it's job. i did that a long time ago and it helped with driveablility a ton.

might do a search on that and see if you can figure that out. i can't really help ya since i was just doing what i was told and didn't realy understand it all that well.

 

no I am scanning with a tech II, I will give it another shot tonight & see how it all turns out.

Thanks everyone for all the help!

 

You can disable the MAF by lowering the fail rate to 0. That will disable it without unplugging it. That way you will still have the IAT sensor working.

 

Yup, that works great... I was told to make sure that all of the P-zero 101, 102, and 103 MAF codes are "enabled". The code must be enabled, but the "dashboard light" part of it can be disabled.

 

I definitely feel your pain, believe me. Erik (TB) here can attest to that.

I just re-read what I wrote - I'm kicking myself because it sure doesn't sound all that easy - but honestly, once you spend some time in it, you'll get up to speed real quick.

Like Flyer said above, I set my MAF fail frequency to 0, and double check those codes I listed.

Using Edit will make this a little harder for me, because I only know the HPTuners way of life.

I used to modify the injector flow rate table, but I reverted back to stock values when I started the SD tuning. SD/VE tuning is kind of like 'reverse engineering' the way the PCM was programmed at the factory.

I believe the correct way to start the SD/VE tune is to disable the MAF, get it out of the picture, and go from there.

Don't worry too much! You don't REALLY need a smoothing button - it's just like that "easy button" commercial I see on TV. I smoothed one over by hand in a few minutes. Does Edit have line graphs or 3D graphs you can view tables with? That make it pretty easy. (If not, let me know - shoot me the numbers, I can copy and paste them into my VE table, smooth it out for you, and send it back in a few minutes)

You sound JUST like I did. Erik helped show me the light.

Let me check around online here and see what the capabilities of Edit and TechII's are... I can give a quick and dirty rundown that will take the pain away from readin some of these SD/VE tuning threads in the PCM section.