VE analyze autotune and MAT correction table
05-09-2011, 10:32 PM
#22
piece of ****.
I did those MAT correction values... Gair is always 100 now...but still lean on heatsoaked/hot start... I dont get it. Car was fine on 80-85 IAT, then when I started it back up after leaving pubelix, it was a little over 100 IAT. Gair was still at 100...but it was running lean. Hot air, and it wasn't pulling any fuel...and it was still lean, im so confused.
I did those MAT correction values... Gair is always 100 now...but still lean on heatsoaked/hot start... I dont get it. Car was fine on 80-85 IAT, then when I started it back up after leaving pubelix, it was a little over 100 IAT. Gair was still at 100...but it was running lean. Hot air, and it wasn't pulling any fuel...and it was still lean, im so confused.
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05-09-2011, 10:33 PM
#23
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^^
when I enable my launch control or flat shift, it sets timing to less than 1 degree of advance. you could make it more like 10 or 5 or something but it works.
the point is to avoid VEAL thinking that the 19:1 AFR spike during flatshift means "add a **** ton of fuel".
when I enable my launch control or flat shift, it sets timing to less than 1 degree of advance. you could make it more like 10 or 5 or something but it works.
the point is to avoid VEAL thinking that the 19:1 AFR spike during flatshift means "add a **** ton of fuel".
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05-10-2011, 09:59 AM
#25
I tried the 100% MAT correction values and the table above. It pulled a crap load of fuel from the VE table. Obviously because it is now adding a lot more from MAT correction table.
I'm still having the same issue below 75 degrees. Although it pulls fuel to make Gair 100% it is still making the car run too lean. Options are to pull a little of the correction, or see if there is another issue.
Brain: You said you are using the Mazda CLT sensor preset??? This moring it was 70 degrees and my CLT in tunerstudio read 91. So something is up with this value. It also seems like the car warms up too quickly with these values. I'm wondering if my car isn't as warm as it appears when I start autotuning at 150* CLT. There is a very large difference between how my car runs at 130 degree and 155 degree when I start autotuning. I may need to increase the temp at which I start autotune to 180 or 190. Then see if this has any affect on the overall stability of my VE table relative to MAT.
I'm still having the same issue below 75 degrees. Although it pulls fuel to make Gair 100% it is still making the car run too lean. Options are to pull a little of the correction, or see if there is another issue.
Brain: You said you are using the Mazda CLT sensor preset??? This moring it was 70 degrees and my CLT in tunerstudio read 91. So something is up with this value. It also seems like the car warms up too quickly with these values. I'm wondering if my car isn't as warm as it appears when I start autotuning at 150* CLT. There is a very large difference between how my car runs at 130 degree and 155 degree when I start autotuning. I may need to increase the temp at which I start autotune to 180 or 190. Then see if this has any affect on the overall stability of my VE table relative to MAT.
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05-10-2011, 10:13 AM
#26
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yeah that's pretty far off. But yes, I use the Mazda Rx7 (s4 & s5) drop down when configuring the CLT.
the tune shouldnt really change that much from just CLT temps, do you have any other enrichments running? when does your warmup enrichements stop? and they stop at 100% right? obviously, the tune will be richer during warmup.
the tune shouldnt really change that much from just CLT temps, do you have any other enrichments running? when does your warmup enrichements stop? and they stop at 100% right? obviously, the tune will be richer during warmup.
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05-10-2011, 10:32 AM
#27
WUE stops at 150* at 100% ( I thought in the past you said you used the "mazda" preset. I'll change mine this afternoon.
I just went over a few morning logs. Baro adds a percent, but that is accurate with my altitude.
I just can't figure out why a tune would change from with temp form hot to cold it the MAT table is dialed in unless I am tuning at a point when the car is not at equilibrium (warm)
The truth is though, I'm much less concerned about reducing how much the MAT pulls fuel while its cool out, then I am about reducing how much it adds when hot.
I'm going to tune above a CLT of 185 and see how that works. If that doesn't fix it, then I'll modify the MAT correction < 70*
I just went over a few morning logs. Baro adds a percent, but that is accurate with my altitude.
I just can't figure out why a tune would change from with temp form hot to cold it the MAT table is dialed in unless I am tuning at a point when the car is not at equilibrium (warm)
The truth is though, I'm much less concerned about reducing how much the MAT pulls fuel while its cool out, then I am about reducing how much it adds when hot.
I'm going to tune above a CLT of 185 and see how that works. If that doesn't fix it, then I'll modify the MAT correction < 70*
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05-11-2011, 12:26 PM
#30
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im in a pretty intersting discussion on heatsoak with the MS developers. ill let you know what the outcome is. Right now I can disable AIT input during ASE. that allows me time for my wbo2 to warm up, then I can use EGO at idle to add/subtract fuel if needed. but i want more, but we haven't figured out the best approach.
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05-11-2011, 12:42 PM
#31
im in a pretty intersting discussion on heatsoak with the MS developers. ill let you know what the outcome is. Right now I can disable AIT input during ASE. that allows me time for my wbo2 to warm up, then I can use EGO at idle to add/subtract fuel if needed. but i want more, but we haven't figured out the best approach.
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05-11-2011, 12:48 PM
#32
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were you reading my last posts?
Originally Posted by 11:57am
...let's assume I'm genuinely heat soaking and I start tinkering with the MAT corrections table to compensate. So at idle, traffic and hot restarts I can maintain stoich when the ideal law demands you need less fuel; this seems to be what everyone is doing.
When it is truely a hot day outside and I may then need less fuel, true to ideal, since I altered the MAT corrections table I'm going to be adding more fuel and have to rely on EGO to pull it back where the ideal law code might have put it. It will add even more so when I'm in boost and running open loop.
Would it then not be a novel idea for a corrections curve that is impletmented only at idle where heat soak sets in, so that you can tweek the corrections a little to maintain stoich, then be able to decay these corrections out with increased RPMs so that they do not effect fueling outside once the sensor is reporting real temps again? Why is there a MAT corrections table implemented to begin with if the ideal law should not be ignored?
When it is truely a hot day outside and I may then need less fuel, true to ideal, since I altered the MAT corrections table I'm going to be adding more fuel and have to rely on EGO to pull it back where the ideal law code might have put it. It will add even more so when I'm in boost and running open loop.
Would it then not be a novel idea for a corrections curve that is impletmented only at idle where heat soak sets in, so that you can tweek the corrections a little to maintain stoich, then be able to decay these corrections out with increased RPMs so that they do not effect fueling outside once the sensor is reporting real temps again? Why is there a MAT corrections table implemented to begin with if the ideal law should not be ignored?
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05-11-2011, 01:33 PM
#33
Great minds think alike. It could also use the origal MAT correction table and just add a user defined multipler table at the same temp positions for the idle table. OR a absolute. I want to subtract 1% from the 2% that is being added by the MAT table to get a net 1% increase in overall fuel added at idle. for the given temp.
In any case, like wher it is headed. I think it is retarded that we have to adjust he MAT table tomake Gir 100% all the time. We should be looking for a modifie gas law equaion. I thoght the goal of the MAT table was to take into account the users unique AIT sensor characteristics, not create a table that our car depnds on to run correctly.
Is the idal gas code not taking into accont the efficiency of the engine? I know we can reduce how extreme it reacts, but maybe it is off because its assuming 100% of the fue is being burned and converted to power. IDK, I'mrambling now so I'll leave it alone.
In any case, like wher it is headed. I think it is retarded that we have to adjust he MAT table tomake Gir 100% all the time. We should be looking for a modifie gas law equaion. I thoght the goal of the MAT table was to take into account the users unique AIT sensor characteristics, not create a table that our car depnds on to run correctly.
Is the idal gas code not taking into accont the efficiency of the engine? I know we can reduce how extreme it reacts, but maybe it is off because its assuming 100% of the fue is being burned and converted to power. IDK, I'mrambling now so I'll leave it alone.
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05-11-2011, 01:41 PM
#34
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you need the ideal code.
But what might not be accounted for is gas vaporization when the temps are hotter, or heat latency value, other things that come into play.
Now that it's getting warmer out I can see if denying the ideal law works. I have a feeling I will find that I may need to add more at idle but subtract at speed. MS1 handled this better where you could decay out the MAT corrections.
The Ideal Gas Law
You might remember from high school physics classes that an ideal gas (which air is reasonably close to) obeys the relationship:
PV = nRT
Where:
P = pressure,
V = volume,
n = number of moles (which is related to the mass of the gas, i.e. 1 mol = 6.023x1023 molecules of the gas, and n = mass (in grams)/molar mass(MM)),
R = the ideal gas constant,
and T = the absolute temperature.
What does this have to do with fuel injection? In order to know how much fuel to inject, we need to know how much air is going into the engine so the chemically correct mixture (called “stoichiometricâ€) can be achieved. So for a fuel injected engine, we use sensors to determine the pressure in the intake manifold and the air temperature. However, the temperature in this equation is “absolute temperature†measured in Kelvins which is equal to degrees Celsius + 273º.
The volumetric efficiency (VE) is a percentage that tells us the pressure inside the cylinder versus the pressure in the manifold. We know the volume (V) from the displacement of the engine. Thus we can calculate the mass of air (M) in the cylinder (proportional to n) from
n = PV/RT
=> M = n x MM = PV/RT x MM
= (VE * MAP * CYL_DISP) / (R * (IAT-32) * 5/9 + 273)) x MMair
Since:
P = VE * MAP (i.e. the pressure in the cylinder in kPa),
V = CYL_DISP = the displacement of one cylinder (in liters),
R = 8.3143510 J/mol K,
and T = (IAT-32)* 5/9 + 273 to convert IAT from ºFahrenheit to Kelvin.
Note that we can combine the constants R and MMair into one, and we will ignore them from this point on since they can be hard-coded into the assembly language code and neglected after that.
Since we now know the amount of air in a cylinder from the MAP and IAT values and the 'tuned' value for VE, we need to know the amount of fuel to inject. We specify this with a parameter called REQ_FUEL.
You might remember from high school physics classes that an ideal gas (which air is reasonably close to) obeys the relationship:
PV = nRT
Where:
P = pressure,
V = volume,
n = number of moles (which is related to the mass of the gas, i.e. 1 mol = 6.023x1023 molecules of the gas, and n = mass (in grams)/molar mass(MM)),
R = the ideal gas constant,
and T = the absolute temperature.
What does this have to do with fuel injection? In order to know how much fuel to inject, we need to know how much air is going into the engine so the chemically correct mixture (called “stoichiometricâ€) can be achieved. So for a fuel injected engine, we use sensors to determine the pressure in the intake manifold and the air temperature. However, the temperature in this equation is “absolute temperature†measured in Kelvins which is equal to degrees Celsius + 273º.
The volumetric efficiency (VE) is a percentage that tells us the pressure inside the cylinder versus the pressure in the manifold. We know the volume (V) from the displacement of the engine. Thus we can calculate the mass of air (M) in the cylinder (proportional to n) from
n = PV/RT
=> M = n x MM = PV/RT x MM
= (VE * MAP * CYL_DISP) / (R * (IAT-32) * 5/9 + 273)) x MMair
Since:
P = VE * MAP (i.e. the pressure in the cylinder in kPa),
V = CYL_DISP = the displacement of one cylinder (in liters),
R = 8.3143510 J/mol K,
and T = (IAT-32)* 5/9 + 273 to convert IAT from ºFahrenheit to Kelvin.
Note that we can combine the constants R and MMair into one, and we will ignore them from this point on since they can be hard-coded into the assembly language code and neglected after that.
Since we now know the amount of air in a cylinder from the MAP and IAT values and the 'tuned' value for VE, we need to know the amount of fuel to inject. We specify this with a parameter called REQ_FUEL.
Now that it's getting warmer out I can see if denying the ideal law works. I have a feeling I will find that I may need to add more at idle but subtract at speed. MS1 handled this better where you could decay out the MAT corrections.
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05-17-2011, 03:39 PM
#36
I had to change back to 50% correction value today. It just wasn't working for me a at 100%. The spread of 16% fuel from low temp to high temp seemed to cause problems. datalogging showed that all of the values in my MAT correction table were zeroing at Gair, but at the same time this morning wasn't adding in enough fuel while in boost.
I'm wondering if it is my new AEM wideband calibration. It might be safer to switch back to the standard calibration in tuner studio. It least then I was sure that my car was .3 rich. I can at least tune that out.
With a 50% MAT value my fuel spread is only about 3%, compared to 16% with a 100% MAT correction value. This 3% spread is manageable since I don't usually get into boost until the car is warm.
I'm wondering if it is my new AEM wideband calibration. It might be safer to switch back to the standard calibration in tuner studio. It least then I was sure that my car was .3 rich. I can at least tune that out.
With a 50% MAT value my fuel spread is only about 3%, compared to 16% with a 100% MAT correction value. This 3% spread is manageable since I don't usually get into boost until the car is warm.
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