Auto rescaling not just scalers but also maps

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NeWT
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Auto rescaling not just scalers but also maps

Post by NeWT » Wed Jun 03, 2015 8:26 pm

Hi, Matt.
I assume to suggest you a thing which probably most of us was thinking about.
I suggest you to make an algorithm of maps rescaling. This algorithm is like a bitmap image resizing. So, when you change the MAF by wizard and when new MAF is selected, we get a new K. So, we know a multiplier coefficient between new and old K. So, I suggest to automatically rescale all TP based maps horizontally to fit them to an old TP range in a new range.
Hope, you understand, what I mean.
Together with a new TID/TIM values it will be fully automatical stock program maker on a new injectors/MAF.
Values on the right cells, which will be unknown as map will be narrowed to the left, you can set to some safe values (10 AFR for fuel for example).

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Mon Jun 08, 2015 2:24 pm

We no longer advocate rescaling TP scales in the maps. This has always been the way everyone has tuned Nissan ECUs because when you adjust K it changes TP (load) which then changes injection

So changing K has the desired effect of changing injection time (when resizing injectors) but the undesired effect of also changing TP load (and require load rescaling)

Adding TIM to feature pack allows adjustment of injector time without affecting load. So load scales always stay the same, and the fuel and timing maps do not need adjusting or resizing

The retuning still requires manual monitoring of AFRs and trims to ensure you are in the correct place with total fueling adjustment

mtnickel
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Re: Auto rescaling not just scalers but also maps

Post by mtnickel » Thu Sep 22, 2016 5:38 am

I still think having a fuel and ignition map be shrunk down could be useful.

For instance:
Lets say your stock map is setup from 8-80TP. Lets also say that the car hits 80TP on just 11psi. We very likely need to create room on the right side of the map for higher TP values. lets say we want to tune out to 25psi that ends up being something like 120TP. If we want our TP scalers to be nice and smooth, we need to rescale them.
Perhaps they were: 8,12,16,20.... They may now need to be 8, 14, 20, 26, ....

The ability to scale or rather import an existing stock map into the lower portion of a new map would be very useful. That way the lower values (from 8-80TP) would still be tuned just like stock and you would only need to do fine tuning on the higher load cells.
You can do this by interpolating the values.
I made an excel program to do just this when I was constructing my maps. It looked something like this:

Image

Having this sort of functionality built in would make creating a basemap very trivial. Note that the TIM does not solve this problem. You are still having to change the upper TP values to account for higher boost.

Note that in this map I didnt' change the RPM values, but it functions over RPM as well. For instance if you want to tune your vehicle up to 8000 RPM and the stock map only goes to 6400, you'd have to rescale all the RPM values.

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Thu Sep 22, 2016 12:55 pm

Lets say your stock map is setup from 8-80TP. Lets also say that the car hits 80TP on just 11psi. We very likely need to create room on the right side of the map for higher TP values. lets say we want to tune out to 25psi that ends up being something like 120TP. If we want our TP scalers to be nice and smooth, we need to rescale them.


What we would do these days, is lower K constant so that TP still reaches 80TP on 25PSI

With the reduction in K that will result in less fuel (say 30%) so then increase Total Injection Multplier by same amount to put fueling back to normal. There is now no need to change the TP scales (and since we are not shifting TP around doesnt affect all the other TP related parameters including knock, acceleration enrichment, and o2 feeback)

mtnickel
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Re: Auto rescaling not just scalers but also maps

Post by mtnickel » Wed Sep 28, 2016 5:56 am

Matt wrote:
Lets say your stock map is setup from 8-80TP. Lets also say that the car hits 80TP on just 11psi. We very likely need to create room on the right side of the map for higher TP values. lets say we want to tune out to 25psi that ends up being something like 120TP. If we want our TP scalers to be nice and smooth, we need to rescale them.


What we would do these days, is lower K constant so that TP still reaches 80TP on 25PSI

With the reduction in K that will result in less fuel (say 30%) so then increase Total Injection Multplier by same amount to put fueling back to normal. There is now no need to change the TP scales (and since we are not shifting TP around doesnt affect all the other TP related parameters including knock, acceleration enrichment, and o2 feeback)


But now you've completely destroyed the stock timing maps and have to tune the entire map from scratch. If you left the timing map as is, then at 25PSI (80TP), you'd be running timing that was originally intended for just 11psi...ie WAY too much timing. This shuffles down the entire map and the whole thing needs to be tuned from scratch.

If you want to Rescale the K constant and Load values like this then it would still be useful to have some sort of rescale feature that still condenses the original tune to work with the updated K constant and TIM.

If you do it your way, then anytime you want to use a bigger MAF or go for more power (high TP) then you're having to retune the entire map.

While I mention only ignition timing the same would apply for the fuel maps, though they are much faster to tune than timing. Proper/stock like timing maps in the low load sections can be tedious to do on a dyno.

"What we would do these days, is lower K constant so that TP still reaches 80TP on 25PSI"
Doesn't this sort of negate the point of the TIM. Wasn't the idea to keep the TP relation to actual load constant so that all the other TP dependant values would not need to be changed? ie. TP min/max's, TP thresholds for VTC, TP thresholds for knock learning, OverRun TP values.

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Wed Sep 28, 2016 8:22 am

Of course the timing map values will need to be redone on boost, because you have increased the boost from 11psi to 25psi.

Timing values themselves nothing to do with our intention of making the ECU stick within the existing factory TP scales

Depending on where the boost is now made (dependent on turbo setup) will now determined what timing values need to be made and where. Most of the high boost will be around the 3/4 mark onwards in the map where timing will be pulled out in blocks

Shifting the ignition timing values left does not fix this problem. It still needs a full retune... You cannot reliably work form the existing factory timing map (even if compressed original values are somewhat moved to the left). What timing values would you plan on 'automatically' filling on the right which would be considered safe?

The point of TIM was to make the ECU work within the same factory TP range as prior to any injector or MAF adjustments. When Nissan mapped these ECUs, the load (TP) ranges were determined and mapped for fuel, timing, knock, O2 sensing etc

We have found that if we adjust K constant only (and consequently this increases/decreases TP) then all those load ranges (and constants - including TP load used to enable VCT for example) would need to be shifted. There are too many TP parameters to change

Keeping TP operating in the factory range makes everything work the same as Nisssan mapped the vehicle, but we can inject more fuel or put on a different MAF sensor and still operate in this range

mtnickel
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Re: Auto rescaling not just scalers but also maps

Post by mtnickel » Wed Sep 28, 2016 1:01 pm

Matt wrote:Of course the timing map values will need to be redone on boost, because you have increased the boost from 11psi to 25psi.

Ideally you would only need to adjust the timing values (or columns) from 11psi to 25psi, not from 25" vac to 25psi.

Matt wrote:Timing values themselves [have] nothing to do with our intention of making the ECU stick within the existing factory TP scales

I think this is where you are misguided. You have some desire to not allow the ECU see a higher TP than what is in the fuel map? But if the ECU thinks 80TP is 14PSI of boost, and you adjust K so that 80TP is now 50PSI of boost, you just confused it. No, TP will not exceed 80, but at the same time lower values of 20TP it thought were low vacuum values, are now actually much much higher engine loads than it thinks.
The fuel map is simply a lookup table. TP is calculated from the MAF signal and RPM and the ECU goes to the table to see what value of fuel (or timing advance) to output. You'll even notice that often the Fuel maps and timing maps have different Maximum TP (timing map on the Z32 ecu goes to 96 vs only 88 on the fuel map).

Matt wrote:Depending on where the boost is now made (dependent on turbo setup) will now determined what timing values need to be made and where. Most of the high boost will be around the 3/4 mark onwards in the map where timing will be pulled out in blocks

Can you get a drivable car only adjusting the high boost values, yes. But why throw out all the stock mapping in the process. The bottom 3/4 of the map should be adjusted as well; many of the values are probably too advanced and above MBT.

Matt wrote:Shifting the ignition timing values left does not fix this problem. It still needs a full retune... You cannot reliably work form the existing factory timing map (even if compressed original values are somewhat moved to the left). What timing values would you plan on 'automatically' filling on the right which would be considered safe?

Only the higher boost columns would need to be changed instead of the entire map. What I did was do roughly what a Hondata (honda tuning) software would do and that is retard roughly .75-1.25* timing PER psi of Boost added. While not exact, a rough aproximation can be made between load and Manifold pressure. Logging on my car revealed about 39TP at 0ATM, 75TP at about 11psi, and about 88TP at 15psi. So for my mapping it turned out to be about 3.16TP per PSI. A wizard could be constructed to help users determine this rough aproximation (likely take inputs of what Vacuum and TP the engine idles at, what TP it's at when at 1ATM, and what TP it hits at maximum boost and what boost pressure that is).

The map could then be constructed such that you pull 1* timing per 3.16TP (or whatever relation your engine has) added up to the maximum TP you want to run. In my case I went from a max TP of 82 to 104. a TP difference of 22 or about 7PSI. So I pulled roughly 7* of timing in my final column. That situation does only work if the final column of your timing map was well tuned (the one you're basing the retard/psi off of). In reality the final column of the stock tune is VERY conservative and so using a fixed value is maybe a more realistic approach (12*? Perhaps give the user control). Once I knew the PSI to TP relation of my engine, I used PowerFC basemaps for the RB25 to create my upper column starting points. Worked out great.

Matt wrote:The point of TIM was to make the ECU work within the same factory TP range as prior to any injector or MAF adjustments. When Nissan mapped these ECUs, the load (TP) ranges were determined and mapped for fuel, timing, knock, O2 sensing etc

I'm amazed you knew you needed TIM yet you are misunderstanding the reason! The ECU doesn't need to operate from 0-80TP all the time. It just needs to operate knowing that say 10Cu Ft of air/sec (maf signal) at a given RPM = a certain engine load (TP!).

You wrote this yourself:
Theoretical Pulse width (TP) = MAF Lookup (VQ lookup) / RPM * K Constant
Injection Pulse width = Fuel table [ RPM , TP/256 ] * TP + Injector Latency + Various enrichment

You need a TIM because you want a shorter fuel pulse width than the ECU is sending. Since the Injection PW uses TP to calculate fuel, our old alternative was to adjust the K constant (and therefore TP) to get shorter injection times. But by changing K constant we are destroying it's ability to convert Air flow to load.

The TIM allowed us to change the PW without changing K const. The only time we will ever want to adjust the K constant is when we are changing the MAF. This is because if we change the MAF without K, the lookup values will show much lower flows than the actual airflow. The idea is that if the MAF can read twice as much air, we reduce K constant in half. 1 MAF * 1 K = 1 = 2 MAF * .5K.

Matt wrote:"What we would do these days, is lower K constant so that TP still reaches 80TP on 25PSI.
With the reduction in K that will result in less fuel (say 30%) so then increase Total Injection Multplier by same amount to put fueling back to normal. There is now no need to change the TP scales (and since we are not shifting TP around doesnt affect all the other TP related parameters including knock, acceleration enrichment, and o2 feeback)"


Your error comes here "we lower K constant". You are lowering part of the equation above and the ECU now is seeing a much lower TP than the actual load on the engine.

The only thing changing the K constant buys you is that you don't have to change the Fuel and Ignition map load scalars. But you just destroyed the reason you made a TIM in the first place which is to keep the airflow to TP load equation the same so all the ECU parameters referencing Load still reference the same (e.g. 10 Cu ft of air = 5 TP)

Correct me where I'm wrong:
Lets say some internal value disables Closed Loop O2 after 50TP. Lets say that corresponds to atmospheric Manifold pressure (50TP ~ 1ATM or 0psi).
Lets also assume we're working from stock fuel maps which range from 10-100TP for the fuel maps. Lets also assume that corresponds to full vacuum (or close to) up to about 14PSI of manifold pressure.
vehicle runs stock with injectors (370CC) and S14 MAF (266HP).
As per your Document:
Theoretical Pulse width (TP) = MAF Lookup (VQ lookup) / RPM * K Constant
And
Injection Pulse width = Fuel table [ RPM , TP/256 ] * TP + Injector Latency + Various enrichment

So step 1) We change to 1000CC injectors. Easy solution, just adjust TIM. Perfect, Nothing in the TP equation has changed, MAF hasn’t changed, and so the proper 1ATM of pressure will cut off O2 feedback at 50TP and we are using 1000CC injectors.
Step 2) We change to a 565HP MAF. K-constant gets changed from 360 to 701.
But since the VQ table of the MAF and K-constant changed equally and oppositely, then the TP equation still holds true (remember the 2 X .5 = 1)

Here are some real values
TP = MAF Lookup /RPM * K Const.
So with Old MAF
VQ lookup =100
RPM = 1000rpm
K Const = 360.
Therefore TP = MAF Lookup (VQ lookup) / RPM * K Constant = 100 /1000rpm * 360 = 36
With the new MAF
VQ lookup would be proportionately lower (voltage would read much lower at the same load), so lets say VQ lookup = 51
RPM = 1000
K Const = 701 now.
So TP = 51/1000 * 701 = 36
This is long winded, but I’m just trying to assert that you can change MAF’s and the same Load values will still be reached on your tune at the same airflow/power levels you were before. Therefore corrections/VTC/Knock limits will all activate at the proper Load.

Step 3) Now lets say I want to tune all the way out to 28PSI of boost. Lets next assume that that would result in a TP of 150 being reached. You are proposing that we should Scale the K constant back such that the 28psi only corresponds to a TP of 100.
Say you scale K Constant 701 back 30% to 490. Sure now you can adjust TIM so that the engine still has proper AFR’s, but you’ve changed the relation of Airflow to actual load.
Using our Example before.
TP = 51/1000 * 490 = 25
By changing the K constant and nothing else, now it’s outputting a TP of 25. So the engine is at 1 ATM of load, but the TP is under registering at 25. So the ECU is waiting to see a TP of 36 to turn off feedback, but the TP is only 25. In fact it might not be till 5-8PSI before the TP catches up thereby throwing off the relation from when those TP values are supposed to kick in and when they actually do.

Matt wrote:Keeping TP operating in the factory range makes everything work the same as Nisssan mapped the vehicle, but we can inject more fuel or put on a different MAF sensor and still operate in this range

Again, the ECU doesn’t need to see 0-100TP and only 0-100TP. It needs to see the relation from airflow to a corresponding TP stay the same.
I’ll try and describe it one more way, and I’ll exaggerate the values.
Stock engine: range 0-100TP in stock Fuel map. 0TP = 0ATM (full vacuum), 50TP = 1ATM, 100TP = 2 ATM (14.7PSI)
Lets say the VTC kicks in at just 20TP which ends up being around 18” vacuum or something like that. Now suppose I put a 2000HP MAF on the car and want to run 5ATM (58PSI) of boost. Doing as you suggest would mean to adjust K so that 100TP = 58PSI. But now 20TP is roughly = 1 ATM! But the ECU still has a value of 20TP before VTC will kick in, but it won’t actually activate till 1ATM (the new 20TP) is reached. By adjusting K to fit Max load to 100TP you are throwing everything else off.

The bottom line is the only reason anyone should ever Adjust K is if they are changing the MAF. If you need to run more load, then increase the scalars in the Fuel and ignition map. And that's why rescaling maps is so important is because you need to create room in the fuel/timing maps to run these higher TP loads.

I'd be happy to skype with you and get a whiteboard out or something to explain it more if you need.

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Thu Sep 29, 2016 11:09 am

Ideally you would only need to adjust the timing values (or columns) from 11psi to 25psi, not from 25" vac to 25psi.

In practise the timing values are not shifted left but completely changed

Matt wrote:
Timing values themselves [have] nothing to do with our intention of making the ECU stick within the existing factory TP scales

I think this is where you are misguided. You have some desire to not allow the ECU see a higher TP than what is in the fuel map? But if the ECU thinks 80TP is 14PSI of boost

We think it is best to keep the ECU operating in the same TP range as previously. I did not say 'fuel map' but usually timing map we use the TP scales of that (same values for fuel and timing)

and you adjust K so that 80TP is now 50PSI of boost, you just confused it.

How is that? The ECU runs over the same trace as factory, and usually only adjustments to timing map are required

No, TP will not exceed 80, but at the same time lower values of 20TP it thought were low vacuum values, are now actually much much higher engine loads than it thinks.

I have not found this to be the case. It appears to trace the same as before. Usually the higher boost starts kicking in half way

The fuel map is simply a lookup table.

Yes very well aware of that. Use the same table routines for flex fuel lookups

TP is calculated from the MAF signal and RPM and the ECU goes to the table to see what value of fuel (or timing advance) to output.

Well the MSB of TP is used to index the tables (not just fuel and timing, but many others)
TP is used as the base fuel injection adjustment input

You'll even notice that often the Fuel maps and timing maps have different Maximum TP (timing map on the Z32 ecu goes to 96 vs only 88 on the fuel map).

Correct. The fuel map will use the values from the last column when TP reads past this column. Normally when tuning we make fuel the same scales as timing (which are longer) and allows us more control

Can you get a drivable car only adjusting the high boost values, yes. But why throw out all the stock mapping in the process. The bottom 3/4 of the map should be adjusted as well; many of the values are probably too advanced and above MBT.

Not necessarily. See my maps attached

Only the higher boost columns would need to be changed instead of the entire map. What I did was do roughly what a Hondata (honda tuning) software would do and that is retard roughly .75-1.25* timing PER psi of Boost added. While not exact, a rough aproximation can be made between load and Manifold pressure. Logging on my car revealed about 39TP at 0ATM, 75TP at about 11psi, and about 88TP at 15psi. So for my mapping it turned out to be about 3.16TP per PSI. A wizard could be constructed to help users determine this rough aproximation (likely take inputs of what Vacuum and TP the engine idles at, what TP it's at when at 1ATM, and what TP it hits at maximum boost and what boost pressure that is).

We cannot assume here that MAF translates to MAP. I would be interested to try this out however and see what correlation there is. One issue is that TP reduces rate of increase as MAF drops down and RPMs increase

I'm amazed you knew you needed TIM yet you are misunderstanding the reason! The ECU doesn't need to operate from 0-80TP all the time. It just needs to operate knowing that say 10Cu Ft of air/sec (maf signal) at a given RPM = a certain engine load (TP!).

Agreed that it does not need to operate the exact same TP range as factory. However if the TP range changes, you cannot only just change fuel and timing TP scales to suit - everything needs to change

The point of TIM is to allow decoupling of K constant and the final injection time

History lesson: When Nissan tuned the S15 MT and AT models, different injectors (480CC/370CC). You will notice all TP related scales, parameters are changed because K constant was changed for injectors. This is why TIM was added, to avoid changing everything for injector size

When we originally tuned vehicles with just K, we found that vehicles which had 740CC/Z32 MAF for example moved the K constant one way (injectors) and then the other way (MAF) were reliable on the road. We originally thought that K had to stay close to the factory value. After adding TIM we moved the injectors using this new parameter, but with Z32 MAF adjustments, the K would be doubled

Some customers would only change MAF (and not injectors) and after rescaling only TP for fuel/timing there were many other issues with vehicle. After K was doubled (TP was also doubled) there were issues with enrichment, knock feedback, O2 feedback and other items. This was because the TP range which those other misc tables operated in were no longer being accessed normally

We found by dropping K until TP operated in the same ranges, the vehicle will operate normally. We also got this feeeback from our customers and now all of them have started tuning this way

You wrote this yourself:
Theoretical Pulse width (TP) = MAF Lookup (VQ lookup) / RPM * K Constant
Injection Pulse width = Fuel table [ RPM , TP/256 ] * TP + Injector Latency + Various enrichment

You need a TIM because you want a shorter fuel pulse width than the ECU is sending. Since the Injection PW uses TP to calculate fuel, our old alternative was to adjust the K constant (and therefore TP) to get shorter injection times. But by changing K constant we are destroying it's ability to convert Air flow to load.

Destroying is a strong work. Altering K contant changes the reported load measured (used by all the tables, and comparitor routines in the ECU) it also changes the pulsewidth.

You are adusting the multipler of how airflow converters to load. The same as when you are changing the MAF on the vehicle you are adjusting the total load that can be read by the MAF.

Our aim is after changing MAF and also the load capacity of the engine (boost) is to compensate K for both (not just one - being MAF resize)

The TIM allowed us to change the PW without changing K const. The only time we will ever want to adjust the K constant is when we are changing the MAF. This is because if we change the MAF without K, the lookup values will show much lower flows than the actual airflow. The idea is that if the MAF can read twice as much air, we reduce K constant in half. 1 MAF * 1 K = 1 = 2 MAF * .5K.

Incorrect. When MAF reads twice as much air - K is doubled (not halved)

Case: S14A SR20DET resize MAF to Z32 and K goes from approx 33,000 to 64,000. Want to resize to a HPX MAF in 3" tube, cannot be done. K cannot go high enough

However does my S14 have the capacity to read the entire 500hp the Z32 can read. Probably not (its 300hp engine) so adjust K back down to what the vehicle can actually use from that MAF (and offset TIM to suit)

Your error comes here "we lower K constant". You are lowering part of the equation above and the ECU now is seeing a much lower TP than the actual load on the engine.

I lower K constant afterwards, where my engine does not see the full capacity of the MAF (so consequently does not read the entire map). Lowering only two TP index tables (timing and fuel) in the entire ECU is not the solution

Correct me where I'm wrong:
Lets say some internal value disables Closed Loop O2 after 50TP. Lets say that corresponds to atmospheric Manifold pressure (50TP ~ 1ATM or 0psi).
Lets also assume we're working from stock fuel maps which range from 10-100TP for the fuel maps. Lets also assume that corresponds to full vacuum (or close to) up to about 14PSI of manifold pressure.
vehicle runs stock with injectors (370CC) and S14 MAF (266HP).
As per your Document:
Theoretical Pulse width (TP) = MAF Lookup (VQ lookup) / RPM * K Constant
And
Injection Pulse width = Fuel table [ RPM , TP/256 ] * TP + Injector Latency + Various enrichment

So step 1) We change to 1000CC injectors. Easy solution, just adjust TIM. Perfect, Nothing in the TP equation has changed, MAF hasn’t changed, and so the proper 1ATM of pressure will cut off O2 feedback at 50TP and we are using 1000CC injectors.

Fuel map needs adjusting here also. About 2.5 x injector size requires map 2.5 x flatter.

Step 2) We change to a 565HP MAF. K-constant gets changed from 360 to 701.
But since the VQ table of the MAF and K-constant changed equally and oppositely, then the TP equation still holds true (remember the 2 X .5 = 1)

The VQ table is only adjusted for the calibration of the MAF itself. It is not opposite.

The airflow capacity of the MAF sensor is increased, so you are assuming that this is half the voltage of the original MAF for same HP reading to reach the same point in the VQ map. But then again the MAF is not linear so there is no guarantee this is correct.

Here are some real values
TP = MAF Lookup /RPM * K Const.
So with Old MAF
VQ lookup =100
RPM = 1000rpm
K Const = 360.
Therefore TP = MAF Lookup (VQ lookup) / RPM * K Constant = 100 /1000rpm * 360 = 36
With the new MAF
VQ lookup would be proportionately lower (voltage would read much lower at the same load), so lets say VQ lookup = 51
RPM = 1000
K Const = 701 now.
So TP = 51/1000 * 701 = 36
This is long winded, but I’m just trying to assert that you can change MAF’s and the same Load values will still be reached on your tune at the same airflow/power levels you were before. Therefore corrections/VTC/Knock limits will all activate at the proper Load.

Check how much lower the VQ would be with the larger MAF. The lower end of the MAF should read approx the same as before, but the upper end will take more airflow to read this higher voltages.

We have seen on the dyno before/after that approximately the same load cells are reached before/after K constant adjustment when calibrating it for the capacity of the vehicle (not the capacity of the MAF). The best way to check this is to do before/after with Z32 MAF and see where TP traces

Step 3) Now lets say I want to tune all the way out to 28PSI of boost. Lets next assume that that would result in a TP of 150 being reached. You are proposing that we should Scale the K constant back such that the 28psi only corresponds to a TP of 100.

Yes this is correct. We want to adjust TP to the capacity of the engine (not the capacity of the MAF after resize

Say you scale K Constant 701 back 30% to 490. Sure now you can adjust TIM so that the engine still has proper AFR’s, but you’ve changed the relation of Airflow to actual load.

We also changed the equation once we swapped in the MAF for one which reads higher capacity than the previous one

Using our Example before.
TP = 51/1000 * 490 = 25
By changing the K constant and nothing else, now it’s outputting a TP of 25. So the engine is at 1 ATM of load, but the TP is under registering at 25. So the ECU is waiting to see a TP of 36 to turn off feedback, but the TP is only 25. In fact it might not be till 5-8PSI before the TP catches up thereby throwing off the relation from when those TP values are supposed to kick in and when they actually do.

I get what you are saying here, but the assumptions are based that the airflow is linear, and that double the size MAF results in exactly half the input measurement in the new MAF and that our K constant rescaling messes this up

The other thing is if you use the old method, you needed to adjust fuel and timing TP scales for the new TP range, but nothing else has been changed which causes the issues I mentioned before


Again, the ECU doesn’t need to see 0-100TP and only 0-100TP. It needs to see the relation from airflow to a corresponding TP stay the same.

I agree with this. The TP can be any range. however all the tables which rely on TP to be a certain range for knock sensing, certain range for VCT, O2 feedback (as well as fuel and timing) will need to be checked and adjusted

You are bascically having to adjust the fuel and timing TP scales, because the TP adjustments using K mean you do not have access to these maps the same way prior to changing the MAF

I’ll try and describe it one more way, and I’ll exaggerate the values.
Stock engine: range 0-100TP in stock Fuel map. 0TP = 0ATM (full vacuum), 50TP = 1ATM, 100TP = 2 ATM (14.7PSI)
Lets say the VTC kicks in at just 20TP which ends up being around 18” vacuum or something like that. Now suppose I put a 2000HP MAF on the car and want to run 5ATM (58PSI) of boost. Doing as you suggest would mean to adjust K so that 100TP = 58PSI. But now 20TP is roughly = 1 ATM! But the ECU still has a value of 20TP before VTC will kick in, but it won’t actually activate till 1ATM (the new 20TP) is reached. By adjusting K to fit Max load to 100TP you are throwing everything else off.

Have you shown this in real life scenario? I have not tried matching boost pressure to TP here (did not think this was possible since we are taking air intake to the engine, divided by RPM as opposed to actual pressure)

What I would do in a real life test is compare two vehicles standard MAF and Z32 MAF for example and see how TP traces in both scenarios and compare that to boost input into the software.

The bottom line is the only reason anyone should ever Adjust K is if they are changing the MAF. If you need to run more load, then increase the scalars in the Fuel and ignition map. And that's why rescaling maps is so important is because you need to create room in the fuel/timing maps to run these higher TP loads.

So do you still also pull K back if you are not using the full capacity of the MAF (300hp on a 500hp MAF) where previously the factory tune was done to approx 80% capacity of the factory (eg SR20DET) MAF?

What about all the other tables? Why are you only changing the scalars of the fuel and ignition tables. There are tons of other tables if you look at disassembled Nissan ECU code which rely on TP which you are not taking into account with TP range being moved around).

I'd be happy to skype with you and get a whiteboard out or something to explain it more if you need.
At this point I would like to run the car on the dyno and check actual figures compared to theoretics due to the variables including the non-linear curves the MAF uses which cannot be calculated without introducing polynomials, air dynamics and pressure into the equations

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Thu Sep 29, 2016 3:24 pm

Tune comparisons as promised. Note: NEO engines suffer from hesistation if the TP is moved too much outside the standard load range.
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madaxgt
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Re: Auto rescaling not just scalers but also maps

Post by madaxgt » Thu Feb 16, 2017 7:05 am

At this point I would like to run the car on the dyno and check actual figures compared to theoretics due to the variables including the non-linear curves the MAF uses which cannot be calculated without introducing polynomials, air dynamics and pressure into the equations


Did you get time to do this? Be interesting to see how the traces around the fuel and ignition maps would compare.

(below relates to non feature pack)
I had concerns about this when I recently swapped mafs on a bnr32 from Z32 to GTR slot MAFs in original 65mm tubes and I understand where mtnickel is coming from. Nothing else was changed and I believe I got the MAF VQ map correct but the car was certainly not really driveable and it was rich at idle then lean. Unfortunately the narrow band O2's were not working so I had to adjust K constant using the wideband to pass inspection quickly then drove the car properly after.

Using the maf resize my vq curve looked much lower than the Z32 curves with the GTR slots in a 65mm tube. Would you expect this? I thought they should be quite close? In fact it looks closer to stock gtr mafs than Z32...

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Thu Feb 16, 2017 4:48 pm

Have not had a chance... there were issues with the turbo on my car. Sent off to Hypergear and a 8 week long wait for the turbo to come back (and the car). Its been refitted but now not getting over 12psi of boost. Just pulled all the pipes off over the last few weeks. Found a small cut in one of them and got that fixed. Now fitted a Garage 7 IPC (boost controller) and testing that and measuring PSI and will see if able to get over 12 PSI... hopefully get it on the dyno soon now

R32 GTR ECU will halve the VQ maps becuase there are two MAF inputs, so that is normal. You will will need to adjust K constant until you get full usage of the map

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Re: Auto rescaling not just scalers but also maps

Post by madaxgt » Thu Feb 16, 2017 6:32 pm

R32 GTR ECU will halve the VQ maps becuase there are two MAF inputs, so that is normal. You will will need to adjust K constant until you get full usage of the map


But it had 2 Z32 mafs swapped to 2 gtr slot style mafs. If you did a calibration compare the maf curves for the new GTR slot curves were much lower than the original mapped calibration with Z32 mafs....
The k constant should not affect the maf curves surely?

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Fri Feb 17, 2017 8:56 am

Attached are the said MAF curves. Both will measure load upto 65535 / 2 = ~32767 which is half of the maximum load value (ECU then add both MAF readings together)

I would say they are only a little lower. However this is not of interest, the main factor with load measurement is the adjustment of K constant (which affects the final TP value)

TP = VQ lookup / RPM x K

The Z32 MAF will measure more load (in 3" tube) than the R35 GTR MAF so a higher K constant is required to get TP operating in the same TP scale range compared to R35 GTR MAF
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Re: Auto rescaling not just scalers but also maps

Post by NeWT » Mon Jun 18, 2018 2:37 am

Wow, wasn't here for a long time. Deep discussions here as I see. mtnickel, you've got what I meant. I fully agree with your conclusions.

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Re: Auto rescaling not just scalers but also maps

Post by Matt » Mon Jun 18, 2018 11:47 am

With the Z32 MAFs, the K constant was 'automatically' recalibrated to maximum capacity of the Z32 MAF, so the car would still drive the same (by adjusting injection time using K only)

The vehicle may not use the full capacity of the MAF to would drive differently and retuning of K/TIM would be required to get unit back to normal.

K constant does not directly affect the curves (conversion from load reference voltage to TP load quantifier) but is a multiplier against this table

TP = RPM/VQ x K

If you agree that you need to adjust TP for boost, you not only need to rescale TP for fuel and timing, but then also find that your VCT, O2 feedback, Knock feedback, throttle enrichment etc are all operating from the previously configured TP scales, then you need to adjust TP for all of those too.

By the time you have done this for all tables, you have adjusted all TP indexing for boost rather than just instead adjust K constant, and then use TIM to fix up the fueling

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