tuning maf with fuel trims
07-12-2016, 06:08 PM
#1
tuning maf with fuel trims correct me if im completely wrong but as long as your ve was dialed in pretty well couldnt you just log maf htz vs fuel trims and use that as a percent error for your maf flow? sorry if this has been gone over before i couldnt find it.
07-15-2016, 07:25 PM
#4
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My opinion is that an unfouled MAF is more accurate than
your fuel pressure or your wideband or for that matter the
switchpoint voltage of your narrowband sensors on which
all trimming depends.
So my first question is, why do you disparage the MAF
accuracy to begin with? Are you sure that it's an air-
side error you are chasing?
If you doubt the MAF, swapping another piece of some
known pedigree (like, new old stock) and looking at the
consistency of output (at same load-points, going by
RPM and MAP, at a few places in the load range) might
save you some work (if they agree) and maybe point
you elsewhere to root out error.
your fuel pressure or your wideband or for that matter the
switchpoint voltage of your narrowband sensors on which
all trimming depends.
So my first question is, why do you disparage the MAF
accuracy to begin with? Are you sure that it's an air-
side error you are chasing?
If you doubt the MAF, swapping another piece of some
known pedigree (like, new old stock) and looking at the
consistency of output (at same load-points, going by
RPM and MAP, at a few places in the load range) might
save you some work (if they agree) and maybe point
you elsewhere to root out error.
07-23-2016, 06:53 PM
#6
My opinion is that an unfouled MAF is more accurate than
your fuel pressure or your wideband or for that matter the
switchpoint voltage of your narrowband sensors on which
all trimming depends.
So my first question is, why do you disparage the MAF
accuracy to begin with? Are you sure that it's an air-
side error you are chasing?
If you doubt the MAF, swapping another piece of some
known pedigree (like, new old stock) and looking at the
consistency of output (at same load-points, going by
RPM and MAP, at a few places in the load range) might
save you some work (if they agree) and maybe point
you elsewhere to root out error.
your fuel pressure or your wideband or for that matter the
switchpoint voltage of your narrowband sensors on which
all trimming depends.
So my first question is, why do you disparage the MAF
accuracy to begin with? Are you sure that it's an air-
side error you are chasing?
If you doubt the MAF, swapping another piece of some
known pedigree (like, new old stock) and looking at the
consistency of output (at same load-points, going by
RPM and MAP, at a few places in the load range) might
save you some work (if they agree) and maybe point
you elsewhere to root out error.
OP of you put the car into MAF only mode you can log MAF htz and tune the part throttle MAF just like you did the VE. For the record though I never recommend using narrowbands for tuning.
Last edited by eaglegoat; 07-23-2016 at 07:04 PM.
07-23-2016, 08:53 PM
#7
[QUOTE=eaglegoat;19337057]WTF are you rambling about?
What he is rambling about is that the MAF is a sensor, and should not need to be tuned unless it is used in some non-stock manner. You wouldn't tune your MAP, IAT, or ECT sensors, would you? That being said, non-stock tubing and orientations can affect a MAF to the point of needing some tuning. In the case of the OP, his username suggests a possibility that the MAF is maxed and no amount of tuning will help a maxed out sensor.
What he is rambling about is that the MAF is a sensor, and should not need to be tuned unless it is used in some non-stock manner. You wouldn't tune your MAP, IAT, or ECT sensors, would you? That being said, non-stock tubing and orientations can affect a MAF to the point of needing some tuning. In the case of the OP, his username suggests a possibility that the MAF is maxed and no amount of tuning will help a maxed out sensor.
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07-23-2016, 09:14 PM
#8
[QUOTE=gametech;19337137] If you think just because it's a stock MAF in a stock car, that it can't be calibrated to a better accuracy then have fun with that. It's a mass produced component, with a mad produced calibration, in a mass produced vehicle. For the record, yes if I had the equipment to fine tune the accuracy of any of those sensors I would. That's what a good tune does is calibrate a smaller margin of error into the response of the computer to the input of the sensors, hopefully resulting in more accurate fueling.
WTF are you rambling about?
What he is rambling about is that the MAF is a sensor, and should not need to be tuned unless it is used in some non-stock manner. You wouldn't tune your MAP, IAT, or ECT sensors, would you? That being said, non-stock tubing and orientations can affect a MAF to the point of needing some tuning. In the case of the OP, his username suggests a possibility that the MAF is maxed and no amount of tuning will help a maxed out sensor.
What he is rambling about is that the MAF is a sensor, and should not need to be tuned unless it is used in some non-stock manner. You wouldn't tune your MAP, IAT, or ECT sensors, would you? That being said, non-stock tubing and orientations can affect a MAF to the point of needing some tuning. In the case of the OP, his username suggests a possibility that the MAF is maxed and no amount of tuning will help a maxed out sensor.
07-23-2016, 11:27 PM
#9
[QUOTE=eaglegoat;19337155] The mass produced vehicle that you theorize also has fuel injectors, fuel pump, o2 sensors, and mass produced engine tolerances that can all affect tuning. What makes you think that the MAF is the one item that is in error? Jimmyblue merely asked "are you sure it's an airside error you are chasing"? You can make an engine run with nothing more than rpm and TB position inputs. The fine tuning that we chase requires a more thorough look at everything.
If you think just because it's a stock MAF in a stock car, that it can't be calibrated to a better accuracy then have fun with that. It's a mass produced component, with a mad produced calibration, in a mass produced vehicle. For the record, yes if I had the equipment to fine tune the accuracy of any of those sensors I would. That's what a good tune does is calibrate a smaller margin of error into the response of the computer to the input of the sensors, hopefully resulting in more accurate fueling.
07-24-2016, 06:24 PM
#10
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I was told by an outfit whose business is calibration, that
their testing of Delphi MAF batches showed the whole bunch
grouped within 5%. They dissuaded me from sending them
MAFs and money, which was sort of odd but OK.
If you look at NBO2 transfer curves temperature makes more
of a difference than that. And all of the zirconia O2 sensors
are known to read false when you have significant exhaust
oxygen (more than stock; stock, this is built into the switch
voltage I expect - there's some reason why platforms differ
in what they call "stoich" switch voltage, by about 25-30%).
Using one uncalibrated sensor to "tune" another sensor's
calibration is a way to make a mess of things. And the
reference instrument of choice is not as true-reading
as you'd like to believe, for the money spent, outside
of reference conditions (i.e. no excess exhaust oxygen
besides what the exhaust stroke pushes out, and a
pretty proper & complete combustion event).
"When you believe in things that you don't understand
then you suffer... superstition ain't the way"
- Stevie Wonder
their testing of Delphi MAF batches showed the whole bunch
grouped within 5%. They dissuaded me from sending them
MAFs and money, which was sort of odd but OK.
If you look at NBO2 transfer curves temperature makes more
of a difference than that. And all of the zirconia O2 sensors
are known to read false when you have significant exhaust
oxygen (more than stock; stock, this is built into the switch
voltage I expect - there's some reason why platforms differ
in what they call "stoich" switch voltage, by about 25-30%).
Using one uncalibrated sensor to "tune" another sensor's
calibration is a way to make a mess of things. And the
reference instrument of choice is not as true-reading
as you'd like to believe, for the money spent, outside
of reference conditions (i.e. no excess exhaust oxygen
besides what the exhaust stroke pushes out, and a
pretty proper & complete combustion event).
"When you believe in things that you don't understand
then you suffer... superstition ain't the way"
- Stevie Wonder
07-24-2016, 06:29 PM
#11
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about how you've done it. What's your golden reference
and your method that makes the MAF air mass value
the only variable and eliminates the other sources of
error?
07-24-2016, 06:48 PM
#12
1) For the same reasons you state, and like I said in my post, tuning with the fuel trims isn't smart.
2) If he's staying closed loop then the fuel trims are overriding what the MAF reads anyway.
3) With a quality WB, and know how, you can trim in the MAF and your o2 sensor corrections.
2) If he's staying closed loop then the fuel trims are overriding what the MAF reads anyway.
3) With a quality WB, and know how, you can trim in the MAF and your o2 sensor corrections.