VE tune changed drastically when MAF re-enabled?
03-13-2009, 05:05 PM
#11
Yeah, I moved like two hours away. But it seems quite a bit colder here in lubbock compared to Midland. And I havent done any VE tuning sense that of last summer. I AM running COS 3 and I DO have some good VE multipliers set up to compensate for IAT changes, and they seem to be working.
I found a MAF tuning config file and it looks fairly simple, so I guess I'll try it and see what happens. Worst case is I run OLSD, I guess. Thanks for the replies.
03-13-2009, 08:45 PM
#12
well...the maf tuning procedure "looked" easy, but I can't seem to get the thing even in the ballpark. 
After 3 logs and reflashes, I gave up for the night and flashed it back to OLSD, which it seems to run well in.
If anyone has any tips on a MAF that just doesn't seem to want to get in line, please share.
After 3 logs and reflashes, I gave up for the night and flashed it back to OLSD, which it seems to run well in.If anyone has any tips on a MAF that just doesn't seem to want to get in line, please share.
03-13-2009, 09:12 PM
#14
Dont use quick throttle changes, ease into the thottle, its fine if it downshifts. First time around I paste special multiply, second and third I paste special multiply by half. After 3 I have found I start chasing my tail, +- 5 is good, +- 3 is better. You arent ever going to get much closer than that day to day since there are too many variables including weather. The closed loop feedback system is there to account for these changes, your just making its job a bit easier.
Last edited by Atomic; 03-13-2009 at 09:27 PM.
03-13-2009, 09:23 PM
#15
Thanks for the tips guys. "Chasing my tail" is exactly what I was doing, lol.
I was at the point that the truck's idle actually dropped and it also had a huge flat spot off idle and at low rpm's...pretty much ran like crap all around...figured I was just getting more and more aggravated and it was probably best to retreat til tomorrow....
I was at the point that the truck's idle actually dropped and it also had a huge flat spot off idle and at low rpm's...pretty much ran like crap all around...figured I was just getting more and more aggravated and it was probably best to retreat til tomorrow....
03-13-2009, 09:37 PM
#16
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whats done to the truck?
you have to be in speed density to tune VE and Maf, go to the help at the top of your screen and hit help, again then in the search type in speed density and it will help you set up the truck. one done with ve set the maf back to stock and set you p0101,102,103 back to normal and dial in the maf. Good luck, you do have a wide band?
you have to be in speed density to tune VE and Maf, go to the help at the top of your screen and hit help, again then in the search type in speed density and it will help you set up the truck. one done with ve set the maf back to stock and set you p0101,102,103 back to normal and dial in the maf. Good luck, you do have a wide band?
03-13-2009, 09:52 PM
#17
whats done to the truck?
you have to be in speed density to tune VE and Maf, go to the help at the top of your screen and hit help, again then in the search type in speed density and it will help you set up the truck. one done with ve set the maf back to stock and set you p0101,102,103 back to normal and dial in the maf. Good luck, you do have a wide band?
you have to be in speed density to tune VE and Maf, go to the help at the top of your screen and hit help, again then in the search type in speed density and it will help you set up the truck. one done with ve set the maf back to stock and set you p0101,102,103 back to normal and dial in the maf. Good luck, you do have a wide band?
I thought you needed to be in SD for tuning VE only?
Everything I could find said re-enable MAF, but disable LTFT's for tuning MAF?
Most every "sticky" I have found on VE or MAF tuning is outdated by a few years...which hasn't helped me at all since some of the info is contradictory.
No wideband yet. I have been using the LTFT's just to tune low and mid rpm only...everything's between 0-3% (from as high as +10%) with MAF out of the loop. With MAF enabled, LTFT's are anywhere from +8%, to as high as +18%
I used this config for the MAF (obviously with no luck yet):
http://www.hptuners.com/forum/attach...0&d=1228098301
03-13-2009, 10:06 PM
#18
You do not have a wideband, so you do not need to be in SD. The way you tune without a wideband is by using the O2 sensors error to correct fueling, ie, LTFT and STFT.
I will use STFT+LTFT until the error is within 10%, then I turn off LTFT and use STFT only.
Tuning the VE takes a long time to do, thats just the nature of the game, you need to get enough data to be useful and there are alot of cells. Some of which you will never hit like the high map - high rpm. Dont worry about that, just make sure the graph is smooth-ish.
Do this, plot LTFT+STFT on the maf frequency table and get as much data as you can Without going into PE. You will know it goes into PE when your commanded AFR drops down. You can filter out those cells if you want which would probably be easier. Stock PE tuning is very rich so you should be fine even if you do enter PE. MAF tuning goes much quicker than VE tuning.
After you plot STFT+LTFT onto MAF frequency, copy everything with labels, open the maf airflow table and paste special multiply by %. If your trim numbers were around ten you can probably turn off LTFTs in the tune. I find doing this makes it easier to get accurate data and you dont have to reset the fuel trims everytime. You can use your same histogram as before since LTFTs will now be zero (reset fuel trims after you turn of LTFT to clear them) so they wont have any effect.
If your error is within 5% paste special multiply by half, if its above 5 paste special multiply.
Run a final scan just to be sure they are within 3%. You can make corrections from here but you will probably not get much closer.
To do WOT tuning, you really need a wideband.
I will use STFT+LTFT until the error is within 10%, then I turn off LTFT and use STFT only.
Tuning the VE takes a long time to do, thats just the nature of the game, you need to get enough data to be useful and there are alot of cells. Some of which you will never hit like the high map - high rpm. Dont worry about that, just make sure the graph is smooth-ish.
Do this, plot LTFT+STFT on the maf frequency table and get as much data as you can Without going into PE. You will know it goes into PE when your commanded AFR drops down. You can filter out those cells if you want which would probably be easier. Stock PE tuning is very rich so you should be fine even if you do enter PE. MAF tuning goes much quicker than VE tuning.
After you plot STFT+LTFT onto MAF frequency, copy everything with labels, open the maf airflow table and paste special multiply by %. If your trim numbers were around ten you can probably turn off LTFTs in the tune. I find doing this makes it easier to get accurate data and you dont have to reset the fuel trims everytime. You can use your same histogram as before since LTFTs will now be zero (reset fuel trims after you turn of LTFT to clear them) so they wont have any effect.
If your error is within 5% paste special multiply by half, if its above 5 paste special multiply.
Run a final scan just to be sure they are within 3%. You can make corrections from here but you will probably not get much closer.
To do WOT tuning, you really need a wideband.
03-13-2009, 10:11 PM
#19
When you turn the MAF back on, your trims go crazy because the computer uses the MAF data first over the VE table. So if your trims are pretty close in SD mode, and then you turn the MAF back on and they are crazy, it means your MAF calibration is off and you need to tune the MAF (see above post).
The VE table comes in mostly at throttle transitions and as a sanity check for the MAF sensor. It is important to have an accurate VE since if anything goes wrong, this is the only way the engine knows how much air it is getting. However important, many people ignore this step because it is a pain in the *** to do, and they just do the MAF table which is much easier and quicker and is the main airflow measure anyway.
The VE table comes in mostly at throttle transitions and as a sanity check for the MAF sensor. It is important to have an accurate VE since if anything goes wrong, this is the only way the engine knows how much air it is getting. However important, many people ignore this step because it is a pain in the *** to do, and they just do the MAF table which is much easier and quicker and is the main airflow measure anyway.
03-13-2009, 10:25 PM
#20
Another note on tuning in general:
Granted I havent been doing this long but I have a pretty good grasp on the underlying concepts of EFI tuning (hptuners, efilive, or whatever your poison may be). The stock tunes are not that accurate because they have to be workable on a huge range of enviroments, and above all, be safe for the componets (engine, trans, etc.). GM does not give vehicles in one climate a different tune than another, which means a truck in the north dakota winter uses the same tune as one in a pheonix summer. If they were to calibrate all trucks for either one of these, then the other one would be severely out of tune. This is an extreme example, but you get the point.
As for tuning a stock vehicle, there isnt much benefit in calibrating the airflow and fuel tables since it runs pretty good (I use this loosely) from the factor. The spark tables could use a good boost, which is what most tunes do to increase power. By stock vehicle, that includes intake/exhaust mods since these arent huge and well within the correctional abilities of the feedback system.
The exception to this is the transmission tuning which will greatly improve the "feel" of your vehicle. Many times I needed to downshift to GTF out of the way but I couldnt because the tune wouldnt let me... trans tuning definately has its benefits on even a stock vehicle.
In my opinion, the most useful thing you get out of tuning a stock vehicle is knowledge and practice. As long as you dont go stupidly far outside of the stock specs you wont break anything since the stock tune is very safe. By practice, I mean for when you decide you want to throw a cam into your truck, you know how to tune it already without having to learn on an untuned cam'd engine, which could be potentially dangerous depending on the size of the cam. Then when you decide to swap heads, TB, add that supercharger, and get the higher stall youve been eyeing, you know basically what your doing.
Once you go past stock (and even for stock WOT), you most definately need a wideband, since outside of stoich its only a guess what your AFR is. If your tune is off and you run 14 afr on 6 pounds of boost at 100% throttle, its not going to be pretty.
I can't remember who said it, but I think it was someone here, "Tuning is not an event, it is an ongoing process." < truth.
Good luck
/end rant
Granted I havent been doing this long but I have a pretty good grasp on the underlying concepts of EFI tuning (hptuners, efilive, or whatever your poison may be). The stock tunes are not that accurate because they have to be workable on a huge range of enviroments, and above all, be safe for the componets (engine, trans, etc.). GM does not give vehicles in one climate a different tune than another, which means a truck in the north dakota winter uses the same tune as one in a pheonix summer. If they were to calibrate all trucks for either one of these, then the other one would be severely out of tune. This is an extreme example, but you get the point.
As for tuning a stock vehicle, there isnt much benefit in calibrating the airflow and fuel tables since it runs pretty good (I use this loosely) from the factor. The spark tables could use a good boost, which is what most tunes do to increase power. By stock vehicle, that includes intake/exhaust mods since these arent huge and well within the correctional abilities of the feedback system.
The exception to this is the transmission tuning which will greatly improve the "feel" of your vehicle. Many times I needed to downshift to GTF out of the way but I couldnt because the tune wouldnt let me... trans tuning definately has its benefits on even a stock vehicle.
In my opinion, the most useful thing you get out of tuning a stock vehicle is knowledge and practice. As long as you dont go stupidly far outside of the stock specs you wont break anything since the stock tune is very safe. By practice, I mean for when you decide you want to throw a cam into your truck, you know how to tune it already without having to learn on an untuned cam'd engine, which could be potentially dangerous depending on the size of the cam. Then when you decide to swap heads, TB, add that supercharger, and get the higher stall youve been eyeing, you know basically what your doing.
Once you go past stock (and even for stock WOT), you most definately need a wideband, since outside of stoich its only a guess what your AFR is. If your tune is off and you run 14 afr on 6 pounds of boost at 100% throttle, its not going to be pretty.
I can't remember who said it, but I think it was someone here, "Tuning is not an event, it is an ongoing process." < truth.
Good luck
/end rant