KKu77

I just finished my SD tune and have gotten my VE table pretty much where I want it (-4 to 0). They were done on a narrowband. My result after a quick drive was this:



Then I put the MAF back on and ended up getting this:



As you can see, I'm running leaner in the lower RPMs than upper RPMs. If i scaled up the entire MAF, to account for the the lower RPMs, won't that cause my upper RPMs to run richer than I'd want? So what's the best way to get my trims back in line?

Some quick background info, this is on a A4 C5 with 220/220 cam, headers, blackwing filter. Thanks!

Karl

TAQuickness

iTrader: (28)

I scaled my maf by taking the average of the B1 and B2 fuel trims, and adding 1/8 of that percentage of the g/s air flow to the current value

Where

new value = current value + ((current value * ((ltftb1 + ltftb2)/2))/8)

This will allow you to make small changes across the board with out over shooting your goals.

jimmyblue

iTrader: (11)

You don't need to scale the MAF table linearly. It looks
like the error is biased to the low end. Get a feel for
how MAF Hz correlates to the MAP*RPM and start
working the MAF table from idle on up, with sort of a
progressive taper (increase the MAF table values more,
the lower the frequency) until you get back to the same
(roughly) STFT histo.

MAF has a hard time being accurate at low airflows.

txhorns281

iTrader: (12)

This is a little more advanced and meticulous, but it works!

https://ls1tech.com/forums/showthrea...hlight=dialing

KKu77

Thanks for the suggestions. I scaled my MAF table by 1.05 up to 4000 and it seems to have gotten the lower RPMs more in line. I need to get some more driving in since my sample was only from about 20 minutes of driving - i'm going by STFT with LTFT disabled. Won't be able to get much in today since we're being pounded with rain, but looks like this weekend will be a busy one.

txhorns281, i'll give that MAF calculator a try and see how things turn out!

RedHardSupra

iTrader: (1)

better MAF calibration spreadsheet:
http://www.allmod.net/hpt

WS6snake-eater

That thing looks kick ***...I'll have to check it out this weekend if I have some free time.

God Forgives I Dont

Thats too ******* cool!!!!!!!!!!!!!!!!!!!!!

I'm also going to give it a shot and I'll post up the results before and after!

One Quick question for you. How did you derive the TQ & HP numbers from the chart on the bottom of that page? Is it just a simple calculation? If so would you educate me on the formula. thanks!!

RedHardSupra

iTrader: (1)

hp=rpm*tq/5252
rpm and tq you got from hpt, hp you just calculate.
i don't think it's real tq numbers, there's been plenty of discussion on it on hpt forums, it's just some estimation that the pcm does, but i frankly don't care, i'm just looking at the relative gains/losses from changes i make. it's easy to throw off the computer too, turn on some accessories and it goes up
i gotta get my gtech going in parallel, it's the only way to see how the power curves shape up.

God Forgives I Dont

Funny you should mention that I just ordered one myself. Granted its the cheaper model because they came out with a newer one that has data logging and a couple of other features but like you said I'll be using it to determine the ganes / losses of mods / tuning. I'm going to get out a here in a few and give your MAF calculator a try after I do some logging. Thanks for letting us check it out!

pknowles

iTrader: (1)

I still think the Dynamic airflow and the MAF airflow should be similar. Scaling the IFR table is a "fix", but still doesn't explain why the two airflows are so different. I only have a lid on my car and logging has revealed that Dynamic airflow and MAF airflow are similar at low flow rates and diverge away from eachother as airflow increases. With my MAF table I see +5 LTFT's at low flowrates and increase to +8 at higher flow rates. My headers should be here on Monday, so I'm not going to play with the MAF until the headers are in since they are going to change things.