Maf tuning that simple?
09-10-2007, 02:23 AM
#1
Launching!
Thread Starter
iTrader: (11)
Join Date: Oct 2006
Location: Ca
Posts: 207
Likes: 0
Received 0 Likes
on
0 Posts
Maf tuning that simple? I made a histogram in hptuners that plots maf hz against dyn airflow in g/sec while in sd mode and compared it to my MAF calibration in the editor. Dyn airflow was higher across the board compared to the MAF , which i was expecting, is it just as simple as pasting the info from the histogram to the maf calibration table? is there more to it? this assuming my fuel trims are accurate....
09-10-2007, 02:45 AM
#2
Assuming the VE table is accurate (trims -> ~0) I see no reason why you couldn't do that and end up with a fair result. Hopefully, someone will chime in.
From what I have gathered, that is all you are doing. Matching up a grams/sec value to the amount of cooling on the MAF element (speed of air).
However, if you generate the grams/sec value yourself and then apply the average term trim maybe this is better? I guess it could depend on how you VE was tuned.
From what I have gathered, that is all you are doing. Matching up a grams/sec value to the amount of cooling on the MAF element (speed of air).
However, if you generate the grams/sec value yourself and then apply the average term trim maybe this is better? I guess it could depend on how you VE was tuned.
09-10-2007, 02:48 AM
#3
Personally, I log % error from commanded AFR against measured AFR and apply that % to the MAF curve. You will find that you are hitting commanded PE after just a few passes like this. Don't forget to reset fuel trims (to reset hidden LT trims that you aren't currently scanning for), disable other things like DFCO, clutch fuel cut, etc so that they don't skew your logging.
09-10-2007, 03:30 AM
#4
Yes, you could.
The AFR is taken of an airflow and being applied to an airflow. I think you could see some error there, but little depending on your tune.
If the VE was nailed down and the airflow generated from the VE to be matched up with the frequency this would allow less possible answers and a better fit.
If the VE wasn't nailed down then it seems like directly going off the WB is the only way. You could get it really close with some careful filtering to remove transients.
Thanx Frost.
The AFR is taken of an airflow and being applied to an airflow. I think you could see some error there, but little depending on your tune.
If the VE was nailed down and the airflow generated from the VE to be matched up with the frequency this would allow less possible answers and a better fit.
If the VE wasn't nailed down then it seems like directly going off the WB is the only way. You could get it really close with some careful filtering to remove transients.
Thanx Frost.
09-10-2007, 06:37 PM
#6
Originally Posted by Frost
I know that RHS has done some math that will generate a MAF curve based off what is beleived to be your near-perfect VE, but adjustment by AFR % error works REALLY well and consistently.
09-14-2007, 03:33 PM
#7
Launching!
Thread Starter
iTrader: (11)
Join Date: Oct 2006
Location: Ca
Posts: 207
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Frost
Personally, I log % error from commanded AFR against measured AFR and apply that % to the MAF curve. You will find that you are hitting commanded PE after just a few passes like this. Don't forget to reset fuel trims (to reset hidden LT trims that you aren't currently scanning for), disable other things like DFCO, clutch fuel cut, etc so that they don't skew your logging.
so....commanded afr maf table
--------------- = -----------
actual afr new maf table ???
and should i set my pe to 1.12 or whatever value makes it around 12.6-13.0 and adust the maf table to get the right afr? or do i set the maf table then adjust the pe value to get the afr i want?
Trending Topics
09-14-2007, 04:20 PM
#8
Originally Posted by SoCal01z28
So your saying the % difference between commanded afr against actual afr should be applied to the g/s value in the maf table?
so....commanded afr maf table
--------------- = -----------
actual afr new maf table ???
and should i set my pe to 1.12 or whatever value makes it around 12.6-13.0 and adust the maf table to get the right afr? or do i set the maf table then adjust the pe value to get the afr i want?
so....commanded afr maf table
--------------- = -----------
actual afr new maf table ???
and should i set my pe to 1.12 or whatever value makes it around 12.6-13.0 and adust the maf table to get the right afr? or do i set the maf table then adjust the pe value to get the afr i want?
PE is a commanded equilivence ratio, to tune correctly your actual should equal your commanded.
Change airflow (maf, or SD) to get the actual to be the same as commanded.
Ryan
09-14-2007, 08:17 PM
#9
Originally Posted by SoCal01z28
So your saying the % difference between commanded afr against actual afr should be applied to the g/s value in the maf table?
so....commanded afr maf table
--------------- = -----------
actual afr new maf table ???
and should i set my pe to 1.12 or whatever value makes it around 12.6-13.0 and adust the maf table to get the right afr? or do i set the maf table then adjust the pe value to get the afr i want?
so....commanded afr maf table
--------------- = -----------
actual afr new maf table ???
and should i set my pe to 1.12 or whatever value makes it around 12.6-13.0 and adust the maf table to get the right afr? or do i set the maf table then adjust the pe value to get the afr i want?
Set PE constant in the beginning to make it easier to get the table right... then (as-noted by slow) apply AFR % error to the MAF table. Make sure you log MAF freq so you know where to change the curve. Once your actual meets commanded fueling (usually only takes just a few passes) then you cna set PE to whatever you want along the curve, or whatever makes th emost power on the rollers.