Landtank MAF surprising scangauge results

[SUMOTOY]

Rescaled MAF

Maybe this will help... I ran a stock N/A 1FZFE engine thru my airflow spreadsheets and came up with max airflow of the 1FZFE at 840lb/hr (quite comfortable margin, I suspect more like 700, but lets assume we can run to 6500 or there is optimistic tabling)

Here is the comparison of the stock MAF meter to one that's just in a larger bore housing. It really doesn't change anything in terms of what has been done. Again, resolution might make a difference in low flow, but MAF's lose resolution as voltage increases. A main reason why rescaling software of a larger MAF is required.

Is it possible to just add larger injectors? Sure, but the fueling will not be as accurate in closed loop operation, because the MAF isn't more accurate, because it is operating below full range. If the maximum air you can put thru a MAF is 850lb/hr, the highest voltage the ecu will ever see with the larger MAF is less than 3.5volts. The ecu tables will never compensate for any voltage over 3.5 because you can't get enough airflow from the engine to make that happen. Specifically (ecu limit = engine air demand limit)

HTH

Scott J
94 FZJ80 Supercharged

 

[semlin]

Suggests, but isn't conclusive in and of itself.

Sumo has the right basic concept, though Slee mentioned it ages ago. Someone needs to go and map out both the OEM and LT setups, then compare. Without hard data, it's all seat-of-the-pants measurements.

i agree it would be interesting to find out. i disagree that someone "needs" to do it. there is zero evidence to support all the hand wringing going on here. basically you are saying these things "could" happen if the maf housing turns out to be so big that it degrades the sensitivity of the new sensor compared to stock. but we are seeing no symptoms whatever of that happening, and instead we are seeing results that suggest the exact opposite.

the underlying premise of this speculation is that the factory ecu somehow cannot use the engine feedback systems to remap the fuel flow based on the varied signal that it will get from landtank's mod whatever peculiarities that signal may have. given that toyota feels that these vehicles can run under boost with a factory ecu, and were engineered to function in third world countries with terrible conditions and maintenance, i highly doubt the ecu is so high strung that it cannot handle a modest increase in unboosted air flow coupled with the benefit of an updated sensor to measure it.

and all this really gets ridiculous when you consider how far people can push the stock ecu in a similar era toyota vehicle like the supra or, for that matter, any other high performance car of that era. this mod is barely a tweak by comparison.

 

[SUMOTOY]

i agree it would be interesting to find out. i disagree that someone "needs" to do it. there is zero evidence to support all the hand wringing going on here. basically you are saying these things "could" happen if the maf housing turns out to be so big that it degrades the sensitivity of the new sensor compared to stock. but we are seeing no symptoms whatever of that happening, and instead we are seeing results that suggest the exact opposite.

Sensitivity decreases with bore diameter. That has nothing to do with which 0-5v sensor you choose to put in.

the underlying premise of this speculation is that the factory ecu somehow cannot use the engine feedback systems to remap the fuel flow based on the varied signal that it will get from landtank's mod whatever peculiarities that signal may have. given that toyota feels that these vehicles can run under boost with a factory ecu, and were engineered to function in third world countries with terrible conditions and maintenance, i highly doubt the ecu is so high strung that it cannot handle a modest increase in unboosted air flow coupled with the benefit of an updated sensor to measure it.

Read the quote from my EFI contact above. If you dump fuel at WOT, the car will not blow up. Specific to this mod alone, the problem is during closed loop operation. With no other changes, I would expect Christo's measures of NOx to go up, because the truck will run lean. Gas mileage could go up too, so could tip in throttle response. The 'conclusions' presented here is that's all good. Propensity for knock to go up increases too.

and all this really gets ridiculous when you consider how far people can push the stock ecu in a similar era toyota vehicle like the supra or, for that matter, any other high performance car of that era. this mod is barely a tweak by comparison.

I don't agree - nor is it Christo's conclusion earlier in this thread. The supra is a turbo application already. Force Induction add-on is a different animal and requires more attention to changes. Regardless, I revived this thread, because Christo supplies a lot of technical references we can go back to.

The purpose of the above charts is to present how MAF's work. More specifically, what a larger MAF can't do, new tech or old tech, the 0-5v signal graph x-y axiis can be scaled, but all MAF follow the same shape. What's better? Me, I claim that's simple, better is the MAF that maxes signal voltage at maximum engine airflow. The variables then, really isn't new vs old 'tech' it's bore diameter and engine air demand.

Scott J
94 FZJ80 Supercharged

 

[semlin]

Maybe this will help... I ran a stock N/A 1FZFE engine thru my airflow spreadsheets and came up with max airflow of the 1FZFE at 840lb/hr (quite comfortable margin, I suspect more like 700, but lets assume we can run to 6500 or there is optimistic tabling)

Here is the comparison of the stock MAF meter to one that's just in a larger bore housing. It really doesn't change anything in terms of what has been done. Again, resolution might make a difference in low flow, but MAF's lose resolution as voltage increases. A main reason why rescaling software of a larger MAF is required.

Is it possible to just add larger injectors? Sure, but the fueling will not be as accurate in closed loop operation, because the MAF isn't more accurate, because it is operating below full range. If the maximum air you can put thru a MAF is 850lb/hr, the highest voltage the ecu will ever see with the larger MAF is less than 3.5volts. The ecu tables will never compensate for any voltage over 3.5 because you can't get enough airflow from the engine to make that happen. Specifically (ecu limit = engine air demand limit)

HTH

Scott J
94 FZJ80 Supercharged

if i assume that a stock housing is 3" in diameter, then to double the airflow you would have to increase the housing diameter by 2 1/4" to 5.25". Are you suggesting that is what was done here? if not, how is that graph relevant?

i agree that if you increase the maf housing beyond a certain point you will cause issues. i think that is self evident. have you calculated the effect of a much more modest increase in air flow size on signal degradation? is it meaningful? is it offset by increases in sensor performance over time? do you have any idea whether the stock housing can handle the engine's maximum air flow potential in the first place.

 

[semlin]

I don't agree - nor is it Christo's conclusion earlier in this thread. The supra is a turbo application already. Force Induction add-on is a different animal and requires more attention to changes.

toyota sells a supercharger add on for this vehicle with no changes to the stock ecu. that suggests the ecu design is just a robust as the supra. so does the fact the vehicle was engineered to operate in extreme conditions and the ecu might have to compensate for problems that could affect air flow (restricted air flow from dust, bad fuel etc...).

 

[SUMOTOY]

if i assume that a stock housing is 3" in diameter, then to double the airflow you would have to increase the housing diameter by 2 1/4" to 5.25". Are you suggesting that is what was done here? if not, how is that graph relevant?

I'm not suggesting anything! Remember, diameter and engine demand increases must hold a constant to the voltage to use the same tabling and add injectors. Specifically, whatever diameter you choose, if you can't get the sensor to reach max voltage (ecu software max voltage) for the given install, the diameter is too big. If it's at max voltage at peak engine demand, it's 'better' I suppose. Logic says that a Force Induction engine will not have the same peak engine demand as a normally aspirated truck.

i agree that if you increase the maf housing beyond a certain point you will cause issues. i think that is self evident. have you calculated the effect of a much more modest increase in air flow size on signal degradation? is it meaningful? is it offset by increases in sensor performance over time? do you have any idea whether the stock housing can handle the engine's maximum air flow potential in the first place.

Not sure I care? Speaking to sensor 'performance' is irrelevent right now. Without software tabling, a sensor can be damn accurate, but the tabling may not be able to differentiate it. I have no idea if the stock housing can handle the engines maximum airflow of a stock truck. I suspect that it does as the MAF for the 1FZFE is not a standard issue toyota MAFM, it's specific to the 80 and the 80 ECU. And at WOT a stock truck dumps fuel too. The MAF is designed to give max voltage to the ecu that the ecu software is looking for. I say it doesn't matter if that's 4.3v or 4.85volts. The ecu processes the maximum voltage from the MAF for the given engine application. If the software says max airflow is 4.3 volts, adding a supercharger isn't going get the software to believe 4.5v is any more than 4.3 volts. Any input 4.3 volts>max signal voltage = 4.3volts to the software. The scamguage may be able to differentiate that increase, but the software won't.

toyota sells a supercharger add on for this vehicle with no changes to the stock ecu. that suggests the ecu design is just a robust as the supra. so does the fact the vehicle was engineered to operate in extreme conditions and the ecu might have to compensate for problems that could affect air flow (restricted air flow from dust, bad fuel etc...).

Big jump... Remember closed loop operation isn't really going to change all that much (MAF app is constant) with a supercharger. Massively different programming with variable boost profiles of a turbocharger. Regardless, as many have shown here with dyno pulls with WOT fuel is just dumped. I suspect that WOT fueling tables are more a function of TPS and RPM than MAF values. I also suspect, if you took a measure of MAF voltage on a SC/Turbo truck, they are maxed sooner than the Normally aspirated truck.

Again, without software tabling changes, pick a value for max voltage signal (easy to measure on a stock truck) Any voltage above max voltage signal will not be differentiated by the software.

Scott J
94 FZJ80 Supercharged

 

[Ebag333]

Not sure I care? Speaking to sensor 'performance' is irrelevent right now. Without software tabling, a sensor can be damn accurate, but the tabling may not be able to differentiate it. I have no idea if the stock housing can handle the engines maximum airflow of a stock truck. I suspect that it does as the MAF for the 1FZFE is not a standard issue toyota MAFM, it's specific to the 80 and the 80 ECU. And at WOT a stock truck dumps fuel too. The MAF is designed to give max voltage to the ecu that the ecu software is looking for. I say it doesn't matter if that's 4.3v or 4.85volts. The ecu processes the maximum voltage from the MAF for the given engine application. If the software says max airflow is 4.3 volts, adding a supercharger isn't going get the software to believe 4.5v is any more than 4.3 volts. Any input 4.3 volts>max signal voltage = 4.3volts to the software. The scamguage may be able to differentiate that increase, but the software won't.

I think the point is that one MAF will not give the same voltage for a certain amount of air flow as another MAF.

The MAF's are designed around a certain volume of air that's expected. You are correct that at the max airflow the ECU will be expecting a max voltage, but that airflow will not be the same from vehicle to vehicle, even if the voltage is (relatively close to) the same.

A 80 a Tercel might both use MAF sensors that range from 0.1v to 5v....but do you really honestly suggest that the Tercel will have as much airflow at 5v as the 80 does?

Switching MAF's is really not much different (in concept) than adding a resistor, all you're doing is changing the input to the ECU and "fooling" it. The ECU doesn't change, it (should) treat 1v the same with the new MAF as it did with the old one.

 

[SUMOTOY]

I think the point is that one MAF will not give the same voltage for a certain amount of air flow as another MAF. The MAF's are designed around a certain volume of air that's expected. You are correct that at the max airflow the ECU will be expecting a max voltage, but that airflow will not be the same from vehicle to vehicle, even if the voltage is (relatively close to) the same.

The shape and profile is the same. I already claim that the airflow won't be the same from vehicle to vehicle, specifically normally aspirated to turbo 80. For this mod on this list, the airflow demand is different. From vehicle to vehicle and from the stock MAF to the modified one.

A 80 a Tercel might both use MAF sensors that range from 0.1v to 5v....but do you really honestly suggest that the Tercel will have as much airflow at 5v as the 80 does?

Nope, but I claim the *same* physical MAF meter is often inserted into a air tube. I know this because I'm currently working through this on a normally aspirated v6 MAF car that uses the identically same MAF meter as a twin turbo application. The difference is the diameter of the tube and the software MAF scaling. Both applications max at the same 4.85v (software tables 214kg/S at max 4.85v the other 310kg/s at max 4.85v respectively), with massively different engine operating parameters and engine demands. The Hot Wire Mass Airflow curves on those tables can be voltage or frequency (GM MAF), it's Mass vs Voltage or Mass vs Frequency. The shape of the slopes are the same, and accuracy is much better at low flow and much less so at high flow.

Switching MAF's is really not much different (in concept) than adding a resistor, all you're doing is changing the input to the ECU and "fooling" it. The ECU doesn't change, it (should) treat 1v the same with the new MAF as it did with the old one.

Without any additional calibration/signal conditioning of some type, all applications are different. You can fool the ecu by adding larger injectors too. Here we have a larger maf without any other calibration to hardware or software, so the current install reflects and follows the above graphs which explains Christo's NOx observations. I might also add, that if you have reached max flow of a hot wire MAF, you can't scale that in any way. It's measuring voltage drop across a wire. You can say the max voltage is something less than 4.85v, but you can't control anything over 4.85v. Once you reach the max air velocity across that sensor you are done with the signal control of that device.

The conditioning of this signal will also need to be changed depending on application. Specifically, the turbo signal conditioning will be different than the normally aspirated. Again, without software, that would be a function of testing Engine Air Demand vs tube size vs max known flow voltage. The voltage value is also less accurate (resolution) as airflow increases. That is what those charts represent. I don't agree that it's a matter of changing resistor values, since MAF based software also assigns Volumetric Efficiency in the tabling. VE will change massively when Force Induction comes into the picture.

Scott J
94 FZJ80 Supercharged

 

[Ebag333]

Nope, but I claim the same MAF meter is inserted into a air tube. I know this because I'm currently working through this on a normally aspirated v6 MAF car that uses the identically same MAF meter as a twin turbo application. The difference is the diameter of the tube and the software MAF scaling.

You might as well be talking about apples and oranges then.

LT's MAF mod is a different meter inserted into a different air tube. You can't assume that for LT's mod it's the same MAF in a different air tube because it's not.

There's 3 parts to this, the MAF sensor, the air tube, and the ECU. With LT's mod the first two change, and the third stays the same. You're talking about the last two, with the sensor staying the same. Those are two completely different discussions, and while your points are interesting they do't really belong in this thread as you are approaching it (as this thread was started specifically about LT's MAF mod, and you're findings ignore half of the mod).

The conditioning of this signal will also need to be changed depending on application. Specifically, the turbo signal conditioning will be different than the normally aspirated. Again, without software, that would be a function of testing Engine Air Demand vs tube size vs max known flow voltage. The voltage value is also less accurate (resolution) as airflow increases. That is what those charts represent.

I don't necessarily disagree with those statements, but again, that's a completely different discussion (though perhaps tangentially related).

 

[semlin]

The MAF is designed to give max voltage to the ecu that the ecu software is looking for. I say it doesn't matter if that's 4.3v or 4.85volts. The ecu processes the maximum voltage from the MAF for the given engine application. If the software says max airflow is 4.3 volts, adding a supercharger isn't going get the software to believe 4.5v is any more than 4.3 volts. Any input 4.3 volts>max signal voltage = 4.3volts to the software. The scamguage may be able to differentiate that increase, but the software won't.

i disagree. in fact that is clearly wrong. the ecu is designed to learn the curve of the particular maf sensor in the truck that is giving it a signal relative to the o2 and other sensor feedback it gets and then to correlate that voltage to a fuel map. it is all relative. no way is the software capped at a particular "4.3 v" maximum voltage because of the expected normal voltage response of the original stock maf sensor. that would be incredibly stupid engineering.

i know this because for my 93 i have a VAF. The VAF test in the FSM allows a voltage signal variation of 1.5 volts when you test it at a certain position. in other words, it can handle two different VAF sensors that generate voltages 1.5 volts apart from the same airflow. VAFs in general are less precise than a MAF system, yet somehow the older ecus cope with the resulting voltage variations without frying engines in closed loop. if a 1993 ECU can handle that much voltage variation relative to airflow then a 97 ECU can certainly handle it.

 

[SUMOTOY]

You might as well be talking about apples and oranges then.
LT's MAF mod is a different meter inserted into a different air tube. You can't assume that for LT's mod it's the same MAF in a different air tube because it's not.

Again, it doesn't matter. Hot wire mafs all operate the same way, they measure a voltage drop for a given voltage in a heated wire by moving air across a wire and measure the voltage drop. Invert that and send that out as a voltage

Once that air exceeds a given velocity the voltage is flat max. You increase the diameter of the tube, you have changed air velocity. Air moving slower means that the voltage gain is also slower, and the absolute values of A or B are irrelevent. It compares bore diameter only Doing both sensor and bore diameter changes without testing can be opined, but I'm not looking to do that. I do claim, the graphs above don't care what sensor you put in B or A. Exchange the two sensors (stock vs new, new vs new, stock vs stock), the A/B relationship won't change. Because the software ECU limit hasn't changed

There's 3 parts to this, the MAF sensor, the air tube, and the ECU. With LT's mod the first two change, and the third stays the same. You're talking about the last two, with the sensor staying the same. Those are two completely different discussions, and while your points are interesting they do't really belong in this thread as you are approaching it (as this thread was started specifically about LT's MAF mod, and you're findings ignore half of the mod).

No, you make this more complicated than I am. Call the value of B the stocker, A is increased Bore. Call A the stocker, call B it the stocker with a smaller bore. The graphs and comparisons don't change.

I don't necessarily disagree with those statements, but again, that's a completely different discussion (though perhaps tangentially related).

MAF operates on the same prinicple. You can't exceed 5 volts on a 5 volt device. You can only scale it's axiis, intentionally, or unintentionally. Two variables to the MAF equation makes it complicated to get the mod right. The choice of sensor is irrelevent here.

Scott J
94 FZJ80 Supercharged

 

[SUMOTOY]

i disagree. in fact that is clearly wrong. the ecu is designed to learn the curve of the particular maf sensor in the truck that is giving it a signal relative to the o2 and other sensor feedback it gets and then to correlate that voltage to a fuel map. it is all relative. no way is the software capped at a particular "4.3 v" maximum voltage because of the expected normal voltage response of the original stock maf sensor. that would be incredibly stupid engineering.

i know this because for my 93 i have a VAF. The VAF test in the FSM allows a voltage signal variation of 1.5 volts when you test it at a certain position. in other words, it can handle two different VAF sensors that generate voltages 1.5 volts apart from the same airflow. VAFs in general are less precise than a MAF system, yet somehow the older ecus cope with the resulting voltage variations without frying engines in closed loop. if a 1993 ECU can handle that much voltage variation relative to airflow then a 97 ECU can certainly handle it.

VAF does not operate on the same principle at all, there is no correlation to MAF sensors. MAF = Mass Airflow Meter. AFM = Air Flow Meter (+ temp input + ecu calculations) = MAF calculated in the tables. The ecu doesn't *learn* anything with regard to MAF. There are just tables, meticulously designed and engineered to Bournulli's laws of flow thru a given size orifice. Just about every OEM manufacturer uses MAF to reflect quite accurate and actual engine airflow to a stock engine. The more accurately you do this, the better the EFI system will work.

By definition the wider you differentiate a 0-5v signal the more accurate the scaling will be of that input device. Add a margin of error for altitude and engine production tolerances, out goes the ecu tables.

Again, the graphs above confirm that, if you use them only as a MAF bore diameter change. In this case, the larger bore diameter is not well suited for the stock ecu programming, because it will never reach the ecu measure limit. The smaller bore diameter MAF has better resolution and uses the best scaling for the programmed limits of the engine air demand.

Welcome to EFI basics!

Scott J
94 FZJ80 Supercharged

 

[96r50]

Toyota uses the same MAF sensor in a number of vehicles (for example, the FJC and the Prius both use 22204-22010). The intake bore is a different size on each of those models (I've seen pictures). My guess would be that Toyota programs each model's ECU to know what the voltage reading means for that particular model. So on an FJC, when the ECU reads 2 volts from the MAF, it would know that corresponds to 10lbs/min of air (I have no idea what units, but it's only an example so ). On the Prius, a 2 volt signal from the MAF might mean 3lbs/min of airflow. So Toyota can use the same MAF in many vehicles and air intakes simply by calibrating the ECU to the specific situation and bore size. (This is my opinion, as I can't see how else they use the same sensor in a large variety of engines/intakes.)

So with regards to our trucks, the stock MAF might be saying X voltage for a certain amount of flow, whereas the LT MAF is saying Y voltage (could be more or less voltage). The ECU has no way to relearn this new voltage range, so it doesn't understand that the same amount of air is flowing through the engine at this new voltage reading. It thinks that at this new Y voltage more/less air is flowing. (I think) it can compensate for this by altering fuel trims/injector durations, but to what end?

It seems to me (in my non-expert engine management systems brain) that for the LT MAF to be a completely drop-in accurate solution it needs to be calibrated to the bore size of the housing so that it puts out the same voltages at the same airflows that the stock MAF does.

IMO YMMV no Holiday Inn's here etc

 

[Ebag333]

Again, it doesn't matter. Hot wire mafs all operate the same way, they measure a voltage drop for a given voltage in a heated wire by moving air across a wire and measure the voltage drop. Invert that and send that out as a voltage

MAF operates on the same prinicple. You can't exceed 5 volts on a 5 volt device. You can only scale it's axiis, intentionally, or unintentionally. Two variables to the MAF equation makes it complicated to get the mod right. The choice of sensor is irrelevent here.

Too bad your "theory" here doesn't match up to reality.

According to your theory (the choice of sensor being irrelevent), the stock 80 MAF and the alternate MAF that LC sourced should act and read the same. The reality is that they do not. The vehicle performs differently, with all else being equal (same air tube, same tables, etc).

The principle and operation behind hit wire MAF's may be the same, but the specification is not. It doesn't matter if 0v and 5v give the same air flow readings if .1v to 4.9v is entirely different. 3v will not be the same air flow on the 80's sensor as a Tercel's. You've already admitted as much, so at this point you are simply contradicting yourself.

 

[SUMOTOY]

Toyota uses the same MAF sensor in a number of vehicles (for example, the FJC and the Prius both use 22204-22010). The intake bore is a different size on each of those models (I've seen pictures). My guess would be that Toyota programs each model's ECU to know what the voltage reading means for that particular model. So on an FJC, when the ECU reads 2 volts from the MAF, it would know that corresponds to 10lbs/min of air (I have no idea what units, but it's only an example so ). On the Prius, a 2 volt signal from the MAF might mean 3lbs/min of airflow. So Toyota can use the same MAF in many vehicles and air intakes simply by calibrating the ECU to the specific situation and bore size. (This is my opinion, as I can't see how else they use the same sensor in a large variety of engines/intakes.)

So with regards to our trucks, the stock MAF might be saying X voltage for a certain amount of flow, whereas the LT MAF is saying Y voltage (could be more or less voltage). The ECU has no way to relearn this new voltage range, so it doesn't understand that the same amount of air is flowing through the engine at this new voltage reading. It thinks that at this new Y voltage more/less air is flowing. (I think) it can compensate for this by altering fuel trims/injector durations, but to what end?

It seems to me (in my non-expert engine management systems brain) that for the LT MAF to be a completely drop-in accurate solution it needs to be calibrated to the bore size of the housing so that it puts out the same voltages at the same airflows that the stock MAF does.

IMO YMMV no Holiday Inn's here etc

Thanks for the post on the Toyota MAF applications and observations. I agree with your 'non-expert engine management systems brain' summaries. To 'compensation' we have no data that presents that yet. As a rule, turbo applications require very accurate MAF scaling.


Scott J
94 FZJ80 Supercharged

 

[Ebag333]

Toyota uses the same MAF sensor in a number of vehicles (for example, the FJC and the Prius both use 22204-22010). The intake bore is a different size on each of those models (I've seen pictures). My guess would be that Toyota programs each model's ECU to know what the voltage reading means for that particular model. So on an FJC, when the ECU reads 2 volts from the MAF, it would know that corresponds to 10lbs/min of air (I have no idea what units, but it's only an example so ). On the Prius, a 2 volt signal from the MAF might mean 3lbs/min of airflow. So Toyota can use the same MAF in many vehicles and air intakes simply by calibrating the ECU to the specific situation and bore size. (This is my opinion, as I can't see how else they use the same sensor in a large variety of engines/intakes.)

Good points. IIRC the MAF sensor that LT sourced is a different part number. Now how that part actually compares to the stock 80 one is anyone's guess.

So with regards to our trucks, the stock MAF might be saying X voltage for a certain amount of flow, whereas the LT MAF is saying Y voltage (could be more or less voltage). The ECU has no way to relearn this new voltage range, so it doesn't understand that the same amount of air is flowing through the engine at this new voltage reading. It thinks that at this new Y voltage more/less air is flowing. (I think) it can compensate for this by altering fuel trims/injector durations, but to what end?

It seems to me (in my non-expert engine management systems brain) that for the LT MAF to be a completely drop-in accurate solution it needs to be calibrated to the bore size of the housing so that it puts out the same voltages at the same airflows that the stock MAF does.

Exactly my thinking.

IMO YMMV no Holiday Inn's here etc

 

[SUMOTOY]

Too bad your "theory" here doesn't match up to reality.
According to your theory (the choice of sensor being irrelevent), the stock 80 MAF and the alternate MAF that LC sourced should act and read the same. The reality is that they do not. The vehicle performs differently, with all else being equal (same air tube, same tables, etc).

They 'act' the same, but they don't read the same, because the bore is different. Bore diameter in A and B is different (A is larger). Pick any 0-5v sensor you want to use for B. Add variable (bore), it will act like A. Take the axiis numbers off and just put in Mass and Voltage (max 5v). 0-5 volt MAF is irrelevent to this exercise.

The principle and operation behind hit wire MAF's may be the same, but the specification is not. It doesn't matter if 0v and 5v give the same air flow readings if .1v to 4.9v is entirely different. 3v will not be the same air flow on the 80's sensor as a Tercel's. You've already admitted as much, so at this point you are simply contradicting yourself.

The specification of 0-5v MAF insert can be exactly the same as represented because the bore is not the same. See Bournulli's law. It can be exactly a different 0-5v MAF, and be exactly represented as graphed, because the bore is not the same. See Bournulli's law.

No contradictions, only misunderstanding of how MAF work? Specifically, how they can't work (I claim they can not defy the laws of physics). If you agree with 96r50, you agree with me. Sorry?


Scott J
94 FZJ80 Supercharged

 

[Ebag333]

They 'act' the same, but they don't read the same, because the bore is different. Bore diameter in A and B is different (A is larger). Pick any 0-5v sensor you want to use for B. Add variable (bore), it will act like A. Take the axiis numbers off and just put in Mass and Voltage (max 5v). 0-5 volt MAF is irrelevent to this exercise.

Bore is the same.

No contradictions, only misunderstanding of how MAF work? Specifically, how they can't work (I claim they can not defy the laws of physics). If you agree with 96r50, you agree with me. Sorry?

Perhaps no intentional contradictions, only a misunderstanding of how LT's MAF mod works? (You do seem to misunderstand mods on a fairly regular basis.)

The bore is not changing, it is using the same housing (LT's custom built one). The ECU and programming is not changing. The sensor is changing. And the results are changing.

96r50 understands that. You, evidentially, do not.

 

[96r50]

Bore is the same.


Perhaps no intentional contradictions, only a misunderstanding of how LT's MAF mod works? (You do seem to misunderstand mods on a fairly regular basis.)

The bore is not changing, it is using the same housing (LT's custom built one). The ECU and programming is not changing. The sensor is changing. And the results are changing.

96r50 understands that. You, evidentially, do not.

To be honest E, the bore is different, as evidenced by the picture attached below. The outside clamping diameter is the same, but the open space inside is clearly less restrictive in LT's MAF housing. So we have two variables: the MAF sensor (specifically its output voltages for given airflow) and the bore size/open space inside the housing.

I've also attached a couple sheets showing the variety of uses of Toyota MAF's in Toyota vehicles. Granted there are a number of part numbers listed in each, but I think it shows the cross compatibility of these sensor (with an ECU properly calibrated for the bore size and output voltage). These sheets are not the gospel by any means as they came from a couple of MAF vendors I found from googling part numbers, but they give an idea of the interchangeability of the sensors

 

[SUMOTOY]

Bore is the same.

'Effective bore' has changed to be larger by definition. As has the sensor. Same principle as taking a screen off a stock Bosch MAF - btdt on a dyno, the measured MAF changes. ECU is calibrated to that MAF (effective) bore and it's obstructions and flow characteristics to engine air demand. If it's the same, the values should be the same. Call it bore or effective bore = same thing. Bernoulli's law is what the toyota engineers use to calibrate the stock sensor to the software. Bernoulli's law would dictate that there is no difference between bore diameter and bore obstruction. A simple test would be voltage stock vs voltage modded.

Perhaps no intentional contradictions, only a misunderstanding of how LT's MAF mod works? (You do seem to misunderstand mods on a fairly regular basis.)
The bore is not changing, it is using the same housing (LT's custom built one). The ECU and programming is not changing. The sensor is changing. And the results are changing.

The effective bore is changing, or you would be able to drop this MAF in without any other changes. The results would change according to the charts above, because the effective bore diameter is larger.

96r50 understands that. You, evidentially, do not.

I understand that changes to sensor design must reflect the same voltage profile as what's in the software, or they are not the same ('effective') bore. Just removing obstructions increases the effective bore of any pipe. Bernoulli's law.

I believe I understand the mod completely. As pictured in post 153 here?
https://forum.ih8mud.com/merchandise-storefront/166370-landtank-performance-maf-housing-6.html
The MAF on the left references 'MAF A' in the charts above, MAF on the right is 'MAF B'. Again, the 0-5v sensor is irrelevant to the concepts I present above. You want to define A and B respective axiis and actual slope to those charts with the ecu software programming? Easy enough, measure the voltage values on a given engine, no other changes than swapping MAF A for MAF B.

Scott J
94 FZJ80 Supercharged