Idle Speed Motor ***SPLIT from Liner Seals***

[DMCVegas]

NOTE: If you're intimidated by all of this math, or simply don't care about these formulas, that's fine. But please skip down to the last paragraph.

We could go down an entire rabbit hole here with this. Diagram looks correct, save for y should be down on the throttle plates (and there should technically be two of them in case the butterflies are either out of sync or one is leaking, or more specifically y to represent the sum of both butterflies with each having it's on representation within a sub-operation), and where you have y, that should be n to represent the sum of all metered air flowing through.

With the idle speed screws, there is a relation to all 3 screws, which is why I wrote the formula the way that I did (which bear with me, my math is a bit rusty), and even then it's probably oversimplified and incorrect unless we want to really get into the weeds on that one. Include the first screw as a way to represent the initial air flow that must be presented to the left & right cylinder bank screws. If it's zero, then everything is zero. If it's open, unless the other screws are open, it's value remains at zero. Once a screw is open, then the screws will only take as much as they're allowed until their metering exceeds that of what the initial screw can provide. If flow is restricted on one side, then the opposite side would take up the unclaimed CFM so long as the first screw can provide it. Which going back to the previous example, if the first screw was cracked to provide 6 CFM and each screw was set to only accept 3 CFM, then we're balanced. But if we increased the opening on the first screw, then the restrictions on the second screws would still only pull 3 CFM each. Assuming of course that we actually got the screws to be that accurate. Given that BOSCH introduced that balancing tube, I seriously doubt they believed most mechanics could ever have the level of accuracy in balancing cylinder banks. Thus the original system was designed to be self-correcting. But like I say, those latter values are intended to be in relation to the first, and we ought to include the flow rate of that first screw if we really want to nail it down.

Then considering the prior formula, perhaps we should look at that again. The fuel flow rates inside of the fuel distributor may not actually be linear in relation to engine demand. They may only be proportional to air flow instead, which means we might actually have f ∝ n

f itself isn't simply an independent value. That is the entire sum of another formula, whereas both formulas are also influencing and affecting one another. Within A:F we've only looked at the A portion. x, y, & z are all items which we have control over (be it purposeful manipulation or automated control by the on-board systems). v was intentionally kept separate as it is the wild card that cannot be controlled, and is practically incalculable due to the sheer amount of variables involved with it. The value of v should always be irrelevant, because the goal should always be to eliminate it and never to accommodate it. Hence why I look down on just disconnecting LAMBDA to solve an issue, but I digress...

With f it has multiple inputs to define it's sum. Which at just a quick glance would include, but not be limited to:

1. Fuel pressure from pump.
2. Line pressure set by the primary pressure regulator
3. WUR line pressure.
4. LAMBDA modulation.
5. Manifold vacuum.
6. Fuel flow rate.

The list here goes on. But even then we have yet another formula we've not spoken about. On an internal combustion engine, combustion is the key word. The three things fire needs to occur? Air, Fuel, and Heat. A:F is no good without Heat to ignite the fuel mixture. Heat comprises both the cooling systems & ignition systems for not only their proper functions, but how they also affect the individual components of both the metered air n and metered fuel f given that temperature affects the baselines of components within those individual systems such as the ISM & Frequency Valve since Idle & LAMBDA have preset values that are temperature-dependent. So we have 3 formulas, A, F, & H which are all interacting with one another!

Last Paragraph.

Now for anyone intimidated by this, or who just doesn't care about the math, this is for you. While this has been a fun little exercise here, the point is that these formulas have always existed. Believe it or not, whenever you're troubleshooting something you're actually performing algebra. Algebra is the fundamental bedrock of troubleshooting. Now I'm not picking on anyone in particular, let alone any DeLorean owners. But far too often whenever someone has a problem, they want someone to tell them what to replace without performing any troubleshooting. I fully believe that a big part of that problem comes from weak mathematical skills which makes the troubleshooting process far too intimidating. Down below I'm going to give an example of a diagram of a simple flashlight. It contains both a schematic, as well as a pictorial diagram of a flashlight (or torch if you're from the rest of the world). The components of the circuit within the schematic tells you in what order the components would be, and the pictorial shows you what they look like and/or their physical location in the real work. Now, what is the goal of any flashlight? To product light of course! So now that you know what the purpose of this device is, you now know what it's desired sum is. And the components of the circuit become components of the formula. So a functioning flashlight should have a mathematical expression of Charged Battery+Positive Wire+Closed Switch+Second Positive Wire+Light Bulb+Negative Wire=Light Now think about what you'd do if you had a flashlight that didn't work. What would you do to troubleshoot it? And BINGO! You're using algebra to troubleshoot.

bulb3.gif

[Ron]

Diagram looks correct, save for y should be down on the throttle plates (and there should technically be two of them in case the butterflies are either out of sync or one is leaking, or more specifically y to represent the sum of both butterflies with each having it's on representation within a sub-operation), and where you have y, that should be n to represent the sum of all metered air flowing through.

Yes, I have that wrong.
[Brain fart- plates became plate's as in metering plate's. And what happened to "Throttle" I don't know, maybe got lost in butterflies = plates or ???]
Anyway, two "y"s would be better, but they should be placed down under (not on) the plates. Lets call the butterfly CFM, b1 & b2.
And n can not go where y is, because it can take from 2 to 4 paths, stock, and up to 6 if all of the screws are open.
To include n, we would have to be split it into n1 & n2 and ignore v, then place each in their respective chamber along with b1 & b2, but immediately before the ports from the CSV tube.
[You didn't comment on notation/definition changes, so I'm continuing with with ((x+y+z=n)+v)/f=Σ, which don't matter because (x+y+z)f+v=Σ is wrong too...]
Note that (x+y+z=n) does not hold because that would be adding the same value (blue arrow flow) twice to z to get n. The diagram is of a stock engine at idle, I.E., the screws and butterflies are closed. So in this case, x=y=n and (x+z)=n and (n+v)/f=Σ.
Fix all that and we have:
In all cases, b1+b2+x+z=n, so (b1+b2+x+v)/f=Σ. z can be broken down into s1 and s2 where z=s1+s2. Giving, (b1+b2+x+s1+s2+v)/f=Σ.
[Makings for a diagnostic tool. But that's as deep into the rabbit hole as I want to go w/o agreeing on notation/definitions. Changing things like p=plate CFM and x to i= ISM CFM would make it easier to follow too.]

With the idle speed screws, there is a relation to all 3 screws, which is why I wrote the formula the way that I did (which bear with me, my math is a bit rusty), and even then it's probably oversimplified and incorrect unless we want to really get into the weeds on that one. Include the first screw as a way to represent the initial air flow that must be presented to the left & right cylinder bank screws. If it's zero, then everything is zero. If it's open, unless the other screws are open, it's value remains at zero. Once a screw is open, then the screws will only take as much as they're allowed until their metering exceeds that of what the initial screw can provide. If flow is restricted on one side, then the opposite side would take up the unclaimed CFM so long as the first screw can provide it. Which going back to the previous example, if the first screw was cracked to provide 6 CFM and each screw was set to only accept 3 CFM, then we're balanced. But if we increased the opening on the first screw, then the restrictions on the second screws would still only pull 3 CFM each. Assuming of course that we actually got the screws to be that accurate. Given that BOSCH introduced that balancing tube, I seriously doubt they believed most mechanics could ever have the level of accuracy in balancing cylinder banks. Thus the original system was designed to be self-correcting. But like I say, those latter values are intended to be in relation to the first, and we ought to include the flow rate of that first screw if we really want to nail it down.

I'm with you on that.

Then considering the prior formula, perhaps we should look at that again. The fuel flow rates inside of the fuel distributor may not actually be linear in relation to engine demand. They may only be proportional to air flow instead, which means we might actually have f ∝ n
...

Depends on exactly what you mean by "engine demand". Assuming, for example, if at idle you stomp it, you and the engine will be demanding full power, it will not get it until time has passed. So the result is not a linear relationship... The fuel rate of the FD depends on the engine demand. But it has to be raised gradually to maintain a combustible AFR. If linear, when you stomped it, the fuel would instantly be delivered at the rate it is when max rpm is met. If you graphed the result as the pedal was pressed, it would be a rising curved line, not a straight one. (All ignoring a slew of things that would change the load...)
Ideally, we want Σ=Final AFR, to be 14.7/1, (f ∝ n). K-Jet...puts up a relatively fair fight...the Lambda system gets it closer.

FlowShut2.jpg

[Giamanut]

NOTE: If you're intimidated by all of this math, or simply don't care about these formulas, that's fine. But please skip down to the last paragraph.

We could go down an entire rabbit hole here with this. Diagram looks correct, save for y should be down on the throttle plates (and there should technically be two of them in case the butterflies are either out of sync or one is leaking, or more specifically y to represent the sum of both butterflies with each having it's on representation within a sub-operation), and where you have y, that should be n to represent the sum of all metered air flowing through.

With the idle speed screws, there is a relation to all 3 screws, which is why I wrote the formula the way that I did (which bear with me, my math is a bit rusty), and even then it's probably oversimplified and incorrect unless we want to really get into the weeds on that one. Include the first screw as a way to represent the initial air flow that must be presented to the left & right cylinder bank screws. If it's zero, then everything is zero. If it's open, unless the other screws are open, it's value remains at zero. Once a screw is open, then the screws will only take as much as they're allowed until their metering exceeds that of what the initial screw can provide. If flow is restricted on one side, then the opposite side would take up the unclaimed CFM so long as the first screw can provide it. Which going back to the previous example, if the first screw was cracked to provide 6 CFM and each screw was set to only accept 3 CFM, then we're balanced. But if we increased the opening on the first screw, then the restrictions on the second screws would still only pull 3 CFM each. Assuming of course that we actually got the screws to be that accurate. Given that BOSCH introduced that balancing tube, I seriously doubt they believed most mechanics could ever have the level of accuracy in balancing cylinder banks. Thus the original system was designed to be self-correcting. But like I say, those latter values are intended to be in relation to the first, and we ought to include the flow rate of that first screw if we really want to nail it down.

Then considering the prior formula, perhaps we should look at that again. The fuel flow rates inside of the fuel distributor may not actually be linear in relation to engine demand. They may only be proportional to air flow instead, which means we might actually have f ∝ n

f itself isn't simply an independent value. That is the entire sum of another formula, whereas both formulas are also influencing and affecting one another. Within A:F we've only looked at the A portion. x, y, & z are all items which we have control over (be it purposeful manipulation or automated control by the on-board systems). v was intentionally kept separate as it is the wild card that cannot be controlled, and is practically incalculable due to the sheer amount of variables involved with it. The value of v should always be irrelevant, because the goal should always be to eliminate it and never to accommodate it. Hence why I look down on just disconnecting LAMBDA to solve an issue, but I digress...

With f it has multiple inputs to define it's sum. Which at just a quick glance would include, but not be limited to:

1. Fuel pressure from pump.
2. Line pressure set by the primary pressure regulator
3. WUR line pressure.
4. LAMBDA modulation.
5. Manifold vacuum.
6. Fuel flow rate.

The list here goes on. But even then we have yet another formula we've not spoken about. On an internal combustion engine, combustion is the key word. The three things fire needs to occur? Air, Fuel, and Heat. A:F is no good without Heat to ignite the fuel mixture. Heat comprises both the cooling systems & ignition systems for not only their proper functions, but how they also affect the individual components of both the metered air n and metered fuel f given that temperature affects the baselines of components within those individual systems such as the ISM & Frequency Valve since Idle & LAMBDA have preset values that are temperature-dependent. So we have 3 formulas, A, F, & H which are all interacting with one another!

Last Paragraph.

Now for anyone intimidated by this, or who just doesn't care about the math, this is for you. While this has been a fun little exercise here, the point is that these formulas have always existed. Believe it or not, whenever you're troubleshooting something you're actually performing algebra. Algebra is the fundamental bedrock of troubleshooting. Now I'm not picking on anyone in particular, let alone any DeLorean owners. But far too often whenever someone has a problem, they want someone to tell them what to replace without performing any troubleshooting. I fully believe that a big part of that problem comes from weak mathematical skills which makes the troubleshooting process far too intimidating. Down below I'm going to give an example of a diagram of a simple flashlight. It contains both a schematic, as well as a pictorial diagram of a flashlight (or torch if you're from the rest of the world). The components of the circuit within the schematic tells you in what order the components would be, and the pictorial shows you what they look like and/or their physical location in the real work. Now, what is the goal of any flashlight? To product light of course! So now that you know what the purpose of this device is, you now know what it's desired sum is. And the components of the circuit become components of the formula. So a functioning flashlight should have a mathematical expression of Charged Battery+Positive Wire+Closed Switch+Second Positive Wire+Light Bulb+Negative Wire=Light Now think about what you'd do if you had a flashlight that didn't work. What would you do to troubleshoot it? And BINGO! You're using algebra to troubleshoot.

bulb3.gif

I love math!

[DMCVegas]

Yes, I have that wrong.
[Brain fart- plates became plate's as in metering plate's. And what happened to "Throttle" I don't know, maybe got lost in butterflies = plates or ???]
Anyway, two "y"s would be better, but they should be placed down under (not on) the plates. Lets call the butterfly CFM, b1 & b2.
And n can not go where y is, because it can take from 2 to 4 paths, stock, and up to 6 if all of the screws are open.
To include n, we would have to be split it into n1 & n2 and ignore v, then place each in their respective chamber along with b1 & b2, but immediately before the ports from the CSV tube.
[You didn't comment on notation/definition changes, so I'm continuing with with ((x+y+z=n)+v)/f=Σ, which don't matter because (x+y+z)f+v=Σ is wrong too...]
Note that (x+y+z=n) does not hold because that would be adding the same value (blue arrow flow) twice to z to get n. The diagram is of a stock engine at idle, I.E., the screws and butterflies are closed. So in this case, x=y=n and (x+z)=n and (n+v)/f=Σ.
Fix all that and we have:
In all cases, b1+b2+x+z=n, so (b1+b2+x+v)/f=Σ. z can be broken down into s1 and s2 where z=s1+s2. Giving, (b1+b2+x+s1+s2+v)/f=Σ.
[Makings for a diagnostic tool. But that's as deep into the rabbit hole as I want to go w/o agreeing on notation/definitions. Changing things like p=plate CFM and x to i= ISM CFM would make it easier to follow too.]

n should be the sum of all air passing through the metering plate to mechanically influence the flow of fuel, regardless if which path it takes to final destination. Add up the sums of the throttle plates, the ISM, and the brass idle screws, and they should always total n. Now when it comes to calculating those individual sums, then that becomes a different story. The sum of the throttle plates/butterflies is always going to be simple addition to add the two together. The idle screws, however, that is a different kettle of fish since we're dealing with proportionality. The ratios of air passing into each cylinder bank via screws 2 & 3 is directly proportional to the constant flow rate of screw 1 which feeds both of them.

In any case, I certainly concur that the naming convention of these components absolutely needs to be sorted out first.

No need for a diagnostic tool. We already know that with the idle speed we have a maximum deviation from the mean of 50 RPMs when LAMBDA is present and active. If we exceed that, then we know there is a problem.

Depends on exactly what you mean by "engine demand". Assuming, for example, if at idle you stomp it, you and the engine will be demanding full power, it will not get it until time has passed. So the result is not a linear relationship... The fuel rate of the FD depends on the engine demand. But it has to be raised gradually to maintain a combustible AFR. If linear, when you stomped it, the fuel would instantly be delivered at the rate it is when max rpm is met. If you graphed the result as the pedal was pressed, it would be a rising curved line, not a straight one. (All ignoring a slew of things that would change the load...)
Ideally, we want Σ=Final AFR, to be 14.7/1, (f ∝ n). K-Jet...puts up a relatively fair fight...the Lambda system gets it closer.

FlowShut2.jpg

Totally agree with you. But the funny there here is that we're debating two completely separate linear curves!

What I am referencing is the position of the metering plate in reference to the fuel flow rates and line pressures to maintain the desired A:F. A mechanical measurement. What you're referencing is the time in which it takes the fuel distributor to raise the line pressures to achieve those desired flow rates. A chronological measurement to achieve the aforementioned targets!

[crbritt83]

As a mathematics major, I can appreciate an attempt at talking some semblance of real mathematics in the forum.

[Ron]

n should be the sum of all air passing through the metering plate to mechanically influence the flow of fuel, regardless if which path it takes to final destination. Add up the sums of the throttle plates, the ISM, and the brass idle screws, and they should always total n. Now when it comes to calculating those individual sums, then that becomes a different story. The sum of the throttle plates/butterflies is always going to be simple addition to add the two together. The idle screws, however, that is a different kettle of fish since we're dealing with proportionality. The ratios of air passing into each cylinder bank via screws 2 & 3 is directly proportional to the constant flow rate of screw 1 which feeds both of them.

??? I believe that is exactly what I have...I think you missed where I said, "Fix all that and we have:" ...Use the definitions etc in the diagram.
(b1+b2+x+s1+s2+v)/f=Σ.

In any case, I certainly concur that the naming convention of these components absolutely needs to be sorted out first.

How about:
A/F = Air Fuel Ratio
M = Metered Air
B1 = Bank 1 Butterfly; B2 = Bank 2 Butterfly
I = ISM Air
S = Idle Screw; s1 = Bank 1 Balance Screw; s2 = Bank 2 Balance Screw;
F = Fuel; Fd = Fuel Distributor; Fx = Fuel Injector, where x = {1, 2,..., 6}; Fc Cold Start Valve;
V = Vacuum Leaks; Vx = Vacuum Leak #x, where x = {1, 2, ...}

The formula would then be (B1+B2+I+s1+s2+V)/F=A/F

I'll change the diagram once we agree...

No need for a diagnostic tool. We already know that with the idle speed we have a maximum deviation from the mean of 50 RPMs when LAMBDA is present and active. If we exceed that, then we know there is a problem.

Agreed, but I meant a tool to identify the source of a problem, E.G., To determine what component(s) are causing a high A/F.
Simplest example might be: (B1+B2+I+s1+s2)/F=15.6/1 => V>0, vacuum leak!

Totally agree with you. But the funny there here is that we're debating two completely separate linear curves!

What I am referencing is the position of the metering plate in reference to the fuel flow rates and line pressures to maintain the desired A:F. A mechanical measurement. What you're referencing is the time in which it takes the fuel distributor to raise the line pressures to achieve those desired flow rates. A chronological measurement to achieve the aforementioned targets!

OK, like I said, I wasn't sure what you meant by "engine demand". I was looking at it as we set the throttle plates' position, which determines the "demand". And the metering plate measures the passing air, as it is (re)positioned by the pressure (while the demand is met. Reaction). I picked the throttle plates because it seemed that you were considering what all was/wasn't linear and/or proportional. And since the function of the FD is to deliver fuel with a mass equal to ~1/14.7 of the mass of the air measured by the metering plate, maintaining a constant AFR, it must be linear. (Of course the WUR's input, control pressure, should be considered....and other things previously mentioned, air density, etc. for K-Jet Basic, add Lambda for Ds.)

To be clear, here I can see the metering plate relationship as linear...and directly proportional.
But, I'm not seeing both curves as linear (for the reasons I mentioned earlier).
(Which, doesn't matter now that we are on the same page...me thinks ;-)

======

JUMP IN, crbritt83!!!

[Ron]

Just read through everything and the NPQ firefighter instructor in me spotted a FWIW:

The three things fire needs to occur? Air, Fuel, and Heat.

The Fire Triangle is obsolete. It has been updated by a Fire Tetrahedron to include "an uninhibited chemical chain reaction (sufficient exothermic reaction energy to produce ignition).

[DMCVegas]

??? I believe that is exactly what I have...I think you missed where I said, "Fix all that and we have:" ...Use the definitions etc in the diagram.
(b1+b2+x+s1+s2+v)/f=Σ.


How about:
A/F = Air Fuel Ratio
M = Metered Air
B1 = Bank 1 Butterfly; B2 = Bank 2 Butterfly
I = ISM Air
S = Idle Screw; s1 = Bank 1 Balance Screw; s2 = Bank 2 Balance Screw;
F = Fuel; Fd = Fuel Distributor; Fx = Fuel Injector, where x = {1, 2,..., 6}; Fc Cold Start Valve;
V = Vacuum Leaks; Vx = Vacuum Leak #x, where x = {1, 2, ...}

The formula would then be (B1+B2+I+s1+s2+V)/F=A/F

I'll change the diagram once we agree...

I can dig it. What I was doing previously was breaking down the individual values of the unique butterflies into a total sum for Throttle. Just as I was also doing for the idle screws. The reason being is that the total is appropriate for an engine with no vacuum leaks when determining the full force of air flow acting upon the metering plate. Once we start chasing imbalances in the cylinder banks, those individual values then become relevant in terms of identifying vacuum leaks versus leakage of those 4 points. Which in the grand scheme of things itself may not actually figure into the actual troubleshooting per se, but it is important to the mathematical theory at work here. Speaking of which...

Agreed, but I meant a tool to identify the source of a problem, E.G., To determine what component(s) are causing a high A/F.
Simplest example might be: (B1+B2+I+s1+s2)/F=15.6/1 => V>0, vacuum leak!

Like I say, unless we have individual MAF sensors on each cylinder bank, it's impossible to determine if these items are leaking by themselves. Modern engines don't even bother with this. But what method modern engines use to monitor for cylinder bank imbalances, we can certainly utilize. https://www.innovatemotorsports.com/products/lc2.php

Using something such as DPI's exhaust with the optional second O₂ bung on the passenger side, we can easily have two of these units running in tandem to show us differences in oxygen level variations in the exhaust gasses to determine imbalances and vacuum leaks. Plus I love this thing because it also has an analog output to mimic the stock narrowband sensor to drive the existing LAMBDA controller. Although any old AFR meter setup would do.

OK, like I said, I wasn't sure what you meant by "engine demand". I was looking at it as we set the throttle plates' position, which determines the "demand". And the metering plate measures the passing air, as it is (re)positioned by the pressure (while the demand is met. Reaction). I picked the throttle plates because it seemed that you were considering what all was/wasn't linear and/or proportional. And since the function of the FD is to deliver fuel with a mass equal to ~1/14.7 of the mass of the air measured by the metering plate, maintaining a constant AFR, it must be linear. (Of course the WUR's input, control pressure, should be considered....and other things previously mentioned, air density, etc. for K-Jet Basic, add Lambda for Ds.)

To be clear, here I can see the metering plate relationship as linear...and directly proportional.
But, I'm not seeing both curves as linear (for the reasons I mentioned earlier).
(Which, doesn't matter now that we are on the same page...me thinks ;-)

======

JUMP IN, crbritt83!!!

Yup, we're almost on the same page. What I was referencing wasn't the FD's ability to maintain the 14.7:1 but rather the internal line pressures to the injectors themselves. Which have an operating rage of 54-80 PSI if I remember correctly. The pressures themselves I don't believe are linear, but absolutely the ability to feed the engine is.

[DMCVegas]

Just read through everything and the NPQ firefighter instructor in me spotted a FWIW:

The Fire Triangle is obsolete. It has been updated by a Fire Tetrahedron to include "an uninhibited chemical chain reaction (sufficient exothermic reaction energy to produce ignition).

UGH! I despise the tetrahedron model!

If the values of the individual components are sufficient enough to induce oxidation, that in and of itself should be considered the chain reaction which completes the triangle to cause a fire. Otherwise, you ain't got no fire! The tetrahedron model completely ignores the individual values of the contributing components and acts as if the chain reaction phase is itself some sort of magical primer that initiates the entire thing, instead of actually being the end product of fire. Likewise extinguishing any blaze isn't simply stopping the chain reaction by itself, but removing one of the three components by removing one or more of them from the chemical reaction.

I feel like the tetrahedron model was nothing more than trying to make fire safety more "hip".

[Ron]

I can dig it. What I was doing previously was breaking down the individual values of the unique butterflies into a total sum for Throttle. Just as I was also doing for the idle screws. The reason being is that the total is appropriate for an engine with no vacuum leaks when determining the full force of air flow acting upon the metering plate. Once we start chasing imbalances in the cylinder banks, those individual values then become relevant in terms of identifying vacuum leaks versus leakage of those 4 points. Which in the grand scheme of things itself may not actually figure into the actual troubleshooting per se, but it is important to the mathematical theory at work here. Speaking of which...

Like I say, unless we have individual MAF sensors on each cylinder bank, it's impossible to determine if these items are leaking by themselves. Modern engines don't even bother with this. But what method modern engines use to monitor for cylinder bank imbalances, we can certainly utilize. https://www.innovatemotorsports.com/products/lc2.php

Using something such as DPI's exhaust with the optional second O₂ bung on the passenger side, we can easily have two of these units running in tandem to show us differences in oxygen level variations in the exhaust gasses to determine imbalances and vacuum leaks. Plus I love this thing because it also has an analog output to mimic the stock narrowband sensor to drive the existing LAMBDA controller. Although any old AFR meter setup would do.




Yup, we're almost on the same page. What I was referencing wasn't the FD's ability to maintain the 14.7:1 but rather the internal line pressures to the injectors themselves. Which have an operating rage of 54-80 PSI if I remember correctly. The pressures themselves I don't believe are linear, but absolutely the ability to feed the engine is.

As promised:
FlowShut3.jpg

I can agreed on all...assuming you agree we do have enough already to determine if there is a vacuum leak w/o individual MAP sensors, just not where it is coming from (can't be the areas defined so far, since they are measured). Maybe we need to make some more assumptions, for now, to avoid the can(s) of worms. Expanding with the same example, a perfect stock engine with a perfect setup could have a high A/F caused by a fuel system leak getting into the air intake....endless rabbit holes going to China.