ltft chasing

**shawnrandolph** · 08-29-2011

Hey guys i got hp tuners recently. Been reading up on using it for about a year now. I had zzp do a dyno tune on it about 2 months ago but i ran out of fuel and had to stop mid way through. It made 260whp and 388 tourqe. I then put in a bigger fuel pump and got the tuner to do the tune myself. The problem is I have been chasing around the ltft's an time there +/- 5 then I do the multiply by half in the maff like your supposed to and there just always on the + side and about the same. I seem to have the lower hz really close like 0.3-0.6 but in the 4000hz to 6000hz they are just always adding 3%-6%. I try to drive as long as I can but I dont live that far away from my work. Is it possible that im just not giving the trims long enough to learn

Mods are:
hp tuners
ported gen v 3.2 pulley
headers
xp cam
ported intake stock heads just spring and retainers changed for cam
n* tb lq4 maff
42lb injectors
built tranny

**darkhorizon** · 08-29-2011

tuning with LTFT is tough because you really can only rely on them after many miles, and with very specific filtering.

The amount of filters you need to run are fairly big... I start by filtering out all cells with a TPS that is not between 3% and 25%... anything outside of that range is typically going to be wrong. Filtering by RPM is also fairly important.

I always found myself going back to a stock maf table at times... those LTFT's can get fairly stupid.

**shawnrandolph** · 08-29-2011

yeah after quite a few changes to the maff table the damn car wouldnt even start lol. So I loaded up the stock one and started all over . I runs awesome now just need to get it a little better. Ive also read on doing this with short term but I guess I dont understand becuase the short terms always changing so much .

I also try not to make any adjustments to the maff table until my stft and ltft are pretty close to each other. I watch my whole log on the charts section and if there really different I dont change anything. Am I going about this logic right?

Thanks about the filters i will do that and see. My idle and cruise are dead nuts

**shawnrandolph** · 08-29-2011

i guess i dont understand about the filters. I mean I know what your saying just dont know how to set it up on the software

**darkhorizon** · 08-29-2011

when you are making logs and creating changes off the logs... you should be filtering out bad data.

Also, when LTFT does not equal STFT, it means that you probalby have bad LTFT information.delievered fueling is the combination of LTFT and STFT... so if you have +5 LTFT and +5 STFT, then you have a total of 10 correction.

**Juanmiguel** · 08-29-2011

Not sure here, but I think Darkhorizon is talking about the filters in the table modifier thingy program, at least that's the one I use. I'm not sure which SW are you using for the trims now Shawn.

But yeah I also filter some of it, make TPS at least over 1%, leave out the trims that are already between + - 4%, only make changes of 10% or less and watch the logs carefully afterwards and compare with pervious ones.

When I first started took me a while to notice that I was moving the trims from the +'s to the -'s and viceversa with each change I made because I used like 30% or so adjustment to the MAF values so I always overshot the target.

I also left out the 0% TPS trims because I kept adding fuel to the idle MAF hz and never got there, I read that it's kind of pointless trying to get them on target on a cammed setup.

Edit:
nevermind I saw you're using HPtuners.

**shawnrandolph** · 08-29-2011

Originally Posted by darkhorizon

when you are making logs and creating changes off the logs... you should be filtering out bad data.

Also, when LTFT does not equal STFT, it means that you probalby have bad LTFT information.delievered fueling is the combination of LTFT and STFT... so if you have +5 LTFT and +5 STFT, then you have a total of 10 correction.

So then if my ltft is +5 and my stft is -5 then wouldnt that equal out to 0? I seen on my logs that my long term will be like +6 and my stft is-3. So do it mutliply my maff by +3. Thanks this is a lil confusing and new to me till I get the hang of it.

**darkhorizon** · 08-30-2011

Originally Posted by shawnrandolph

So then if my ltft is +5 and my stft is -5 then wouldnt that equal out to 0? I seen on my logs that my long term will be like +6 and my stft is-3. So do it mutliply my maff by +3. Thanks this is a lil confusing and new to me till I get the hang of it.

That is right.. but 99/100 times if you make that change.. the PCM will just pick some other random values to trim at... The O2 sensor system gets mad when it is not doing some sort of trimming..... You are also relying on some fairly quickly gathered information from that O2 sensor at that instant in time... which is a bit presumptious.

Basically, I stopped doing any maf tune like this YEARS ago... i could always fiddle with injector values and correct mechanical issues to make trims a non-issue.... Running a cam as you noticed makes most types of tuning at low RPMs impossible.

**shawnrandolph** · 08-30-2011

darkhorizon could you please explain a little more detailed cuz in starting to realize that the stickys on here are good information but not the same way everyone tunes. Mabe I just need a different way for me to learn.

I started going by the stft's yesterday but on my way to work today my laptop battery died so I ordered a new one. It only gets about 20 mins on a full charge.

Hptuners also stated that you cant have your laptop plugged in to charge while using their product due to voltage spike and what not. How many of you wrecked your hptuner by doing this?

**shawnrandolph** · 08-30-2011

If I knew how to upload scans Id just do that for you guys

**Overkill** · 08-30-2011

Never wrecked my tuner by having the laptop plugged in

**shawnrandolph** · 08-30-2011

Thanks overkill that saves me alot of hassle

**Reptile** · 08-30-2011

Originally Posted by Overkill

Never wrecked my tuner by having the laptop plugged in

X2

My inverter has a surge protector in it that cuts power when the voltage spikes or drops. My old laptop battery would only last about 20 minutes before it tanked, so I pretty much had to have one.

**FoSHO99** · 08-30-2011

I have to take the battery out of the laptop while leaving the laptop plugged in to flash. If the car's voltage becomes a problem, i usually park by the garage or somewhere i can run a drop cord through the window. Maybe it's time to get a netbook.

**shawnrandolph** · 08-31-2011

okay Ill use it to scan and then unplug it for flashing.
Update:
Got my fuel trims really good and im wot tuning right now. Im up to 16* of timing with no kr yet. Im just working slow at it.

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