Ductape

Hi, all. I've been studying up on tuning; HPT is on the way. One thing I'm not clear on is WHEN (under normal operation) the VE table controls fueling and WHEN the MAF controls fueling. And is it VE _or_ MAF logic, or are the values combined or averaged in the logic at times?

I'm trying to understand the control software behind the tables is how I would state the question. What makes me ask is that we have to disable the MAF during VE tuning. It seems like once we re-enabled the MAF then the VE tuning would be for naught... clearly there are times when MAF computations are in charge and there are other times when VE computations are in charge of the result.

Please help me understand this.
Thanks!
Mike

PS- I see where some people disable the MAF altogether and run just SD logic all the time- thats seems clear.

02sierraz71_5.3

iTrader: (2)

Thats a good questiong the pcm seems to rely on the maf more at part throttle operation and not so much at wot but you can tweak wot fueling with the maf table and if you dial in the ve and have no wot trimming then reenable the maf and have wot trimming you need to tweak the curve, thats the only instance I like to use the maf to tune wot fuel the rest is in the pe table.
Both the ve table and the maf table need to be tuned once they both line up and jive togethor it makes for very consistent fueling throughout any type of weather and you can tell a difference in the way the motor will run. I currently run both and on the cars I tune, both tables are adjusted and it works very well. Look at the sticky at the top for the methods I use.

foff667

iTrader: (1)

This should help

http://www.hptuners.com/forum/showpo...97&postcount=3

foff667

iTrader: (1)

actually, over 4000 rpms(or whatever you have the crossover point set to) the maf takes over completely so technically you could leave the ve table alone & just tweak the maf table to get your commanded to = your actual. For most bolt on cars this is what I do. 2 wot pulls & your actual=commanded +/-1%

dewmanshu

iTrader: (4)

elaborate please. We have a table to change this?

foff667

iTrader: (1)

of course we do

Engine-Airflow-dynamic airflow-dynamic airflow-high rpm disable.

dewmanshu

iTrader: (4)

thnx

02sierraz71_5.3

iTrader: (2)

or you can lower the fail over hz so anytime the maf reads over a set amount it goes to solely Ve table, this is good for boosted apps with a map that cant read positive pressure

dewmanshu

iTrader: (4)

i have never played with that...BUT, if I lowered that to say, 100RPM I could be running on MAF only at all times and then use the MAF histogram and be set right? AWESOME! (not leaving it so but just for tuning the MAF)

dewmanshu

iTrader: (4)

i did this on holty's truck and it worked great for a day. Then it decided to not play nice after i left. Is their a status bit or something we can put in the table watch and be sure it is switching between the 2. You know besides the maf code that is thrown. Which brings the question...once the maf code is thrown, will the pcm revert back to using the maf INSTANTLY once you go below the maf hrtz fail rate? I ask because the code is staying there for sure.