If I want to do a tune WITH the MAF, should I unplug it and speed density tune 1st??
10-21-2004, 06:12 AM
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If I want to do a tune WITH the MAF, should I unplug it and speed density tune 1st?? A couple questions. I hope you don't find them too repetitive, but I'm trying to straighten out what I know about tuning:
1) If I want to get a good tune WITH the MAF, should I start by unplugging it and getting a good tune WITHOUT the MAF (Speed Density) and then once I get that, plug the MAF back in and adjust the MAF translation function?
2) With the MAF plugged in and operating, can I still adjust fueling via the VE table?
3) What is the "Secondary VE Table" anyway??
Thanks.
1) If I want to get a good tune WITH the MAF, should I start by unplugging it and getting a good tune WITHOUT the MAF (Speed Density) and then once I get that, plug the MAF back in and adjust the MAF translation function?
2) With the MAF plugged in and operating, can I still adjust fueling via the VE table?
3) What is the "Secondary VE Table" anyway??
Thanks.
10-21-2004, 07:32 AM
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I'll try to help some.
1) I'd like to know this as well.
2) You can adjust VE with the MAF plugged in, but most people's fuel trims were not changing when they did this.
3) Secondary VE table is what the car uses when you unplug the MAF. So if you unplug the MAF with intentions to tune and then put it back on, I would assume you need to tune the secondary table and then fill in the primary table with those values and try to fill in the extra spots as best you can (primary table has more resolution, ie. cells).
1) I'd like to know this as well.
2) You can adjust VE with the MAF plugged in, but most people's fuel trims were not changing when they did this.
3) Secondary VE table is what the car uses when you unplug the MAF. So if you unplug the MAF with intentions to tune and then put it back on, I would assume you need to tune the secondary table and then fill in the primary table with those values and try to fill in the extra spots as best you can (primary table has more resolution, ie. cells).
10-21-2004, 08:03 AM
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1) If you are willing to take the time in mapping out the true
VE then tuning SD should be the best. I just have "backed
into" my VE table changes, tuning for effect or against
misbehaviors. The methods seem to be evolving as more
people give it a try. There are experimental ways to get a
pretty good true-VE data map (even easier / broader if you
have a wideband meter that's loggable). But even with the
narrowbands if you drive with the MAF off and closed loop
disabled you can get info about rich/lean and optimize your
way to a centered VE value (at least in the cells you can hit).
2) With MAF plugged in, speed density still dominates some
operating regions - idle / low RPM, throttle transients. VE
table changes produce 1:1 effect where pure SD is working,
less effect when the MAF starts being "blended in" to the
calculations and no effect except transient where the MAF
is the sole airflow value. This funky "blending" accounts for
why VE changes appear to have no effect in some area or
only partial effect on some FTCs' LTFT values.
3) Later years (like mine) only have a Primary VE Table.
The Secondary is like every other row of the Primary. So
you could do something like in Excel, where you make a
Secondary source table template, and a Primary target
template that pulls in and spreads the Secondary rows,
and fills in the gaps with the average of (above+below/2)
or something like that, so when you past in the Secondary
you get a copy-n-pastable Primary badda-bing.
VE then tuning SD should be the best. I just have "backed
into" my VE table changes, tuning for effect or against
misbehaviors. The methods seem to be evolving as more
people give it a try. There are experimental ways to get a
pretty good true-VE data map (even easier / broader if you
have a wideband meter that's loggable). But even with the
narrowbands if you drive with the MAF off and closed loop
disabled you can get info about rich/lean and optimize your
way to a centered VE value (at least in the cells you can hit).
2) With MAF plugged in, speed density still dominates some
operating regions - idle / low RPM, throttle transients. VE
table changes produce 1:1 effect where pure SD is working,
less effect when the MAF starts being "blended in" to the
calculations and no effect except transient where the MAF
is the sole airflow value. This funky "blending" accounts for
why VE changes appear to have no effect in some area or
only partial effect on some FTCs' LTFT values.
3) Later years (like mine) only have a Primary VE Table.
The Secondary is like every other row of the Primary. So
you could do something like in Excel, where you make a
Secondary source table template, and a Primary target
template that pulls in and spreads the Secondary rows,
and fills in the gaps with the average of (above+below/2)
or something like that, so when you past in the Secondary
you get a copy-n-pastable Primary badda-bing.
10-21-2004, 12:08 PM
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A couple more questions based on your replies:
4) How do I disable PE? Should I also back off timing to avoid detonation with PE disabled? I also heard some rumor that the transmission starts shifting extremely hard with the MAF disconnected. Is that true?
5) What's the best way to drive to hit the most "cells" possible? Is there some kind of driving routine I can use?
6) When looking at "cells," is the best way to do this to collect as much data as possible, then create a table with MAP ranges on one axis and RPM ranges on another and see what the average LTrims are in each grouping and adjust the VE in the corresponding "cell" accordingly?
7) Am I correct in saying that increasing numbers in the VE table tells the computer to add more fuel?
8) Is there any formula to determine HOW much influence the MAF has over the air/fuel ratio at a given RPM/load?
Thanks for bearing with me.
-Mark
4) How do I disable PE? Should I also back off timing to avoid detonation with PE disabled? I also heard some rumor that the transmission starts shifting extremely hard with the MAF disconnected. Is that true?
5) What's the best way to drive to hit the most "cells" possible? Is there some kind of driving routine I can use?
6) When looking at "cells," is the best way to do this to collect as much data as possible, then create a table with MAP ranges on one axis and RPM ranges on another and see what the average LTrims are in each grouping and adjust the VE in the corresponding "cell" accordingly?
7) Am I correct in saying that increasing numbers in the VE table tells the computer to add more fuel?
8) Is there any formula to determine HOW much influence the MAF has over the air/fuel ratio at a given RPM/load?
Thanks for bearing with me.
-Mark