MAF tuning screwy on my car
05-27-2005, 02:28 PM
#1
MAF tuning screwy on my car I have my ve dialed in so good that on 4 days in a row...with some varrying weather... all my LTFT's were -1 to +1
I plugged back in the MAF....logged a crapload of data
REset Fuel trims... did a lot more driving....
used the allmod.net hpt Maf spreadsheet....
reset fuel trims again....
more driving...
.
and all my LTFT's are in the -14 to -4 range????
what else can cause this....
I plugged back in the MAF....logged a crapload of data
REset Fuel trims... did a lot more driving....
used the allmod.net hpt Maf spreadsheet....
reset fuel trims again....
more driving...
.
and all my LTFT's are in the -14 to -4 range????
what else can cause this....
05-27-2005, 03:13 PM
#3
Originally Posted by SSpdDmon
Were you tuning for 13.0 or 14.7 on the VE table?
all my upper throttle stuff was still kind of close..but I saw most of the -14 stuff in the lower throttle/cruise control areas...
05-27-2005, 03:50 PM
#4
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Originally Posted by soundengineer
tuning for 14.7 using o2's for ve table
all my upper throttle stuff was still kind of close..but I saw most of the -14 stuff in the lower throttle/cruise control areas...
all my upper throttle stuff was still kind of close..but I saw most of the -14 stuff in the lower throttle/cruise control areas...
05-27-2005, 04:37 PM
#6
Originally Posted by RedHardSupra
if car runs fine in SD but MAF makes it go crazy, it means MAF is severly miscalibrated.
Its a stock MAF descreened only....
shouldnt be too far off..and your spreadsheet shows that is only varies slightly in the upper HZ side of the scale
05-27-2005, 04:40 PM
#7
Originally Posted by soundengineer
I used your spreadsheet to recallibrate....
Its a stock MAF descreened only....
shouldnt be too far off..and your spreadsheet shows that is only varies slightly in the upper HZ side of the scale
Its a stock MAF descreened only....
shouldnt be too far off..and your spreadsheet shows that is only varies slightly in the upper HZ side of the scale
descreened can be way off.........
if the VE tune is right and all the problems start when the MAF is put on then the problem is with the MAF/MAF table.....
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05-27-2005, 04:42 PM
#8
I am logging
Mass Air Flow Hz
Dynamic Airflow lb/min
correct???
sort by Dynamic Airflow and remove all 0 values...
copy and paste into 1st sheet..
let it calculate...
go to second sheet....
0 out "old values"....let it calculate.....
go to 3rd sheet....
copy paste orange boxes.....well..all that dont say div/0..
right??
Mass Air Flow Hz
Dynamic Airflow lb/min
correct???
sort by Dynamic Airflow and remove all 0 values...
copy and paste into 1st sheet..
let it calculate...
go to second sheet....
0 out "old values"....let it calculate.....
go to 3rd sheet....
copy paste orange boxes.....well..all that dont say div/0..
right??
05-27-2005, 04:43 PM
#9
the spreadsheet doesn't eliminate room for error. some people can't read the details and log in metric, others have injectors all screwed up resulting in 'funny' ve table and making dynamic air to be 'off'. i've seen dirty MAF/screen/airfilter producing large numbers of flaky data causing the calibration to be iffy at best.
there's a lot of ways this can go wrong. make sure your basics are all taken care of, then do the maf, and you should end up with a much better car.
there's a lot of ways this can go wrong. make sure your basics are all taken care of, then do the maf, and you should end up with a much better car.
05-27-2005, 04:59 PM
#12
Originally Posted by RedHardSupra
the spreadsheet doesn't eliminate room for error. some people can't read the details and log in metric, others have injectors all screwed up resulting in 'funny' ve table and making dynamic air to be 'off'. i've seen dirty MAF/screen/airfilter producing large numbers of flaky data causing the calibration to be iffy at best.
there's a lot of ways this can go wrong. make sure your basics are all taken care of, then do the maf, and you should end up with a much better car.
there's a lot of ways this can go wrong. make sure your basics are all taken care of, then do the maf, and you should end up with a much better car.
already cleaned the MAF thinking that myself....and new airfilter when I did my Longtubes 2 weeks ago..
stock injectors...and stock table for injectors...
05-27-2005, 05:06 PM
#13
Originally Posted by RedHardSupra
umm...and what does afr has to do with maf calibration? are you tuning ve now with maf? why not just go back to tuning ve with ifr?
how about for this novel concept: tune ve with ve! the fact that something kinda works doesn't mean it's right...
how about for this novel concept: tune ve with ve! the fact that something kinda works doesn't mean it's right...
if the MAF is throwing off a tuned VE table then the MAF has everything to do with the air/fuel ratio....
05-27-2005, 08:21 PM
#14
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Originally Posted by 2001CamaroGuy
if the MAF is throwing off a tuned VE table then the MAF has everything to do with the air/fuel ratio....
At the higher frequencies it gets real tough to get 100 data points without either renting speedway or going to jail. You can really see the need for resolution there. It took me about 6 40 minute logging sessions to get what I needed, and it turns out my stock MAF for 98 Vette is the Monaro's curve. I plugged it in after tuning STFT's and it didn't budge.
05-27-2005, 08:46 PM
#15
Originally Posted by dvanorder
How many data points do you have for your MAF calibration? Are there at least 100 data points for each frequency 'bin' in Marcin's sheet? Without that resolution the data will be skewed since there are bogus non-zero value variations that must be averaged out.
At the higher frequencies it gets real tough to get 100 data points without either renting speedway or going to jail. You can really see the need for resolution there. It took me about 6 40 minute logging sessions to get what I needed, and it turns out my stock MAF for 98 Vette is the Monaro's curve. I plugged it in after tuning STFT's and it didn't budge.
At the higher frequencies it gets real tough to get 100 data points without either renting speedway or going to jail. You can really see the need for resolution there. It took me about 6 40 minute logging sessions to get what I needed, and it turns out my stock MAF for 98 Vette is the Monaro's curve. I plugged it in after tuning STFT's and it didn't budge.
I just do pulls with my laptop reading Wideband O2 air/fuel and MAF frequency, compare (say 12.5:1 @ 3500HZ), and adjust (remove say 2%)....then run again.....
after a number of runs things clear up.......
and one does not need to peg the speedo to tune......thats why you have different gears........
05-27-2005, 09:26 PM
#16
I have 3 hours worth of logs....2 ways......there and back...lost of data...
still way off....
am I logging the wrong thing???
Mass Air Flow Hz
Dynamic Airflow lb/min
are these teh 2 items I need to log???
and they go into the spreadsheet in that order...or reversed....
still way off....
am I logging the wrong thing???
Mass Air Flow Hz
Dynamic Airflow lb/min
are these teh 2 items I need to log???
and they go into the spreadsheet in that order...or reversed....
05-27-2005, 09:46 PM
#18
Originally Posted by soundengineer
I have 3 hours worth of logs....2 ways......there and back...lost of data...
still way off....
am I logging the wrong thing???
Mass Air Flow Hz
Dynamic Airflow lb/min
are these teh 2 items I need to log???
and they go into the spreadsheet in that order...or reversed....
still way off....
am I logging the wrong thing???
Mass Air Flow Hz
Dynamic Airflow lb/min
are these teh 2 items I need to log???
and they go into the spreadsheet in that order...or reversed....
Hz is fixed in the MAF but means nothing (other than what "cell" to look in)...
dynamic airflow is what you tell the computer a Hz (cell) is equal to.....
just look at the Hz vs. air/fuel......if you are lean @ __ Hz then mult. by 1.02 and try again.......if rich @ ___ Hz then mult. by 0.98......
05-27-2005, 09:48 PM
#19
Originally Posted by soundengineer
and If they are all -12 -14 -8...do I subtract??? or add to the MAF scale....
I'm going to do this teh hard and tedious way soon....looking at each range and seeing how close I can get..1 section at a time If necessary...
I'm going to do this teh hard and tedious way soon....looking at each range and seeing how close I can get..1 section at a time If necessary...
if you are rich (-LTrims) then take fuel out (mult by 0.98)
if you are lean (+LTrims) then add fuel (mult by 1.02)
05-27-2005, 09:52 PM
#20
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Originally Posted by 2001CamaroGuy
I just do pulls with my laptop reading Wideband O2 air/fuel and MAF frequency, compare (say 12.5:1 @ 3500HZ), and adjust (remove say 2%)....then run again..after a number of runs things clear up...
-Gary