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Discussion Starter #3
NO




NO

Brevity is the soul of Clarity!
I was so pissed at this answer until I realized i didn't phase my question correctly. :p

For a 100% stock Spyder, the air fuel ratio gets more rich as load (perhaps better thought of as TPS since load is often used to refer to injector demand?) increases for a given RPM, and also gets more rich as RPM increase under WOT.

One way to compensate for a significant chunk of that mixture change (make the mixture stay the same instead of leaning out under increasing throttle) is to reference the manifold instead of atmosphere with the fuel pressure regulator. Since the spyder doesn't reference manifold pressure for the fuel pressure regulator, the injectors must supply less fuel at the same duty cycle with the throttle open than closed. Putting this together with the fact that the mixture gets richer, I'd have to conclude that there is some sort of trim applied elsewhere to increase the duty cycle in response, which was my suspicion and what I wanted to know more about.
 

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I was so pissed at this answer until I realized i didn't phase my question correctly. :p

For a 100% stock Spyder, the air fuel ratio gets more rich as load (perhaps better thought of as TPS since load is often used to refer to injector demand?) increases for a given RPM, and also gets more rich as RPM increase under WOT.

One way to compensate for a significant chunk of that mixture change (make the mixture stay the same instead of leaning out under increasing throttle) is to reference the manifold instead of atmosphere with the fuel pressure regulator. Since the spyder doesn't reference manifold pressure for the fuel pressure regulator, the injectors must supply less fuel at the same duty cycle with the throttle open than closed. Putting this together with the fact that the mixture gets richer, I'd have to conclude that there is some sort of trim applied elsewhere to increase the duty cycle in response, which was my suspicion and what I wanted to know more about.
If you're referring to a stock setup, the Toyota engineers invested probably thousands of manhours into programming the OEM ECU to account for all of the things your mention when the engine's operating in the open loop regime.
If you're referring to a setup with an aftermarket EMS (supplemental piggyback or standalone), that's where tuning comes in - whether using a "fixed" FPR (e.g., the stock one) or a FPR that's pressure referenced to the IM. Doing the latter won't be a magic bullet that will eliminate the tuning challenge, but it's a much more elegant approach for a heavily modded engine.
If you're willing to risk potential problems by leaning out the AFR in open loop (as the factory tune is likely on the safe (or slightly rich) side of ideal, you might want to contact Cap Weir who (I believe) has some tricks up his sleeve for doing that.
 

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I was so pissed at this answer until I realized i didn't phase my question correctly. :p

For a 100% stock Spyder, the air fuel ratio gets more rich as load (perhaps better thought of as TPS since load is often used to refer to injector demand?) increases for a given RPM, and also gets more rich as RPM increase under WOT.

One way to compensate for a significant chunk of that mixture change (make the mixture stay the same instead of leaning out under increasing throttle) is to reference the manifold instead of atmosphere with the fuel pressure regulator. Since the spyder doesn't reference manifold pressure for the fuel pressure regulator, the injectors must supply less fuel at the same duty cycle with the throttle open than closed. Putting this together with the fact that the mixture gets richer, I'd have to conclude that there is some sort of trim applied elsewhere to increase the duty cycle in response, which was my suspicion and what I wanted to know more about.
This has soo many errors in it.. it's hard to know where to start..

But I think the Main Problem is, you are ONLY looking at this from a Fuel Stand Point..

It's Not Just Fuel.. It's a Ratio of Air to Fuel.. and how it relates to the Engine and Cat..

It sounds like you somehow have the Fuel Injector Pulse Width Tied to the TPS ONLY.. and then the Fuel Pressure must be changed to fit the New Pulse Width of the Injector.. to keep the Fuel/Air Ratio Proper..

ALL of the Various Sensors feed into the ECU, and the ECU will perform Calculations to set a new Injector Pulse Width.. The Only way the ECU can Control the Air/Fuel Mixture on a Drive by Cable T-Body set up, is to Control the Injector Pulse Width... then in CLosed Loop the Resultant AFR is Sniffed by the O2 Sensors.. and a New Error is Figures, then added to the Last Calculation, and a New Solution is Output to the Injectors.. and this Process is Repeaded...

With the Fuel Pressure as a Constant, the Fuel Delevered will be a Known.. There will actually be some errors, as the MAP Pressure is Changing and the Fuel Pressure is Not.. the the Flow Rates will be higher at Part Throttle, and Lower at WOT for the same Injector Pulse Width.. but SOMEHOW, Some Map in the ECU is Fixed for that error..


As for Fuel Mixture.. Few Coments.. my 'Learnings..'

Best Cruse Lite Load is a Mixture of 15.7 AFR.. you can push into heavy Loads with these Mixtures.. but won't make much Power.. and temps will start to rise FAST.. Don't keep it there for Long.. Engine runs Shitty at Heavy Loads at these AFR's

Best Power is 13.7 AFR.. this is where the Burn is the 'Best'.. but Heavy engine use in this AFR Range MIGHT start to heat up Cylinders.. and WILL Heat up the Cat Converter.. and if Maintained Opperation in this AFR Range Cat Damage will result..

14.7 is the 'Perfect Mixture' .. but it's only good for Smog Compliance.. and to keep the Cat Converter from being Wounded.

Usually the 'Power Band' will be set at 13.5.. when tuners set Mixtures.. but the Cat Converter will be wounded..

The Reading I have Done Indicates the Overly Rich Mixture in WOT is to Protect the Cat Converter from damage while Pulling Long Hills.. or heavy Loads in Trucks and Pick-Ups..

To cool the Engine as it gets hotter in the heaver load bands.. a Richer than Normal Mixture CAN be used to cool the Engine Internals.. The Burn Rate will Change.. and Ignition Timing will have to be Changed..

Also to Cool the Engine Internals.. a Water or Water Meth Mixture can be used..

EDIT: For a Stock Spyder.. the AFR's Will Be 14.7 after warm up. and ALL partal Throttle Running Conditions of Light Load, the AFR's will be 14.7.. When heavy Loads are Calculated by the ECU, the AFR's will snap from 14.7 to 13... then as the Loads Increase the AFR's will fall to the low 12's..

Now with the Basics on the Table.. what are you trying to do?.. or are you just Figuring??..

Cap
 

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More Spyder Ramblings..

The Stock Fuel Pressure is about 44 PSI.. that is what Mine is.. There is some conflicting Information about the Size of the Stock 1ZZ Green Injectors.. some say 260.. some say 280.. I don't know..

The Error Calculations for the O2 Sniffing is Located in Two Pairs of Maps.. On is the 'Error Difference that has always worked in the Past'.. and that is called the Long term Fuel Trim.. And the Other Pair of Maps are the 'New Error' Maps.. called the Short Term Fuel Trims.. the two Maps are added together to be part of the 'Final Solution' calculations for this round of Fueling..

The Trim Maps, could be reduced to only One Set of Maps ( Bank One and Bank Two ).. and that would Work.. but the Calculations would always be adding Large Numbers to the Factory Base Maps.. and the Numbers would be almost Meaningless to Humans.. if the 'Trim Map' was bouncing between +22.06 and +28.85.. the Numbers look Mostly the Same.. and the Human would thing all is Fine..

But if the Long Average of the Trim ( For this Load Cell) is saying +22.06 and the Short Average is Bouncing 0 to +6.85.. that is the same thing.. but seeing the short moving close to 5 is an indicator of something moving.. Less than 5 is good.. but closer to zero is better .. you'll never get zero.. but close is good..

There was likely other factors then Easy Human Reading.. but it does make it a snap to see what is going on..

EDit: Ant the Spyder ECU will run Mostly fine without the TPS.. it's only used to predict when to add fuel for Quick Throttle Movements, that would otherwise cause a Lean Spot in the Throttle Movement.. Without the TPS, if you roll on the Throttle Sowly, you will never feel the Lean Spot.. Roll on Quick.. and you will..

The Only Sensors the ECU gets really pissed about not having is the MAF.. as it cant Calculate engine load.. and will limit RPM to 2800.. and Crank Sensor.. as it wont know where to put the Spark.. The Engine will run without the other sensors.. but depending upon the sensor.. some decrease in performance is expected..
Cap
 

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Discussion Starter #7
I've clearly mis-communicated badly, and yet i still got quite a bit of great info from the responses! I was going to ask about several points you touched on, such as the stock injector size, transient fueling off the TPS, and more!

Clarifications:

I'm approaching this area I don't know enough about the same way I approached suspension mods a long time ago. Learn the hows and whys of the stock system, the hows and whys of typical mods, and then start modifying based on understanding how things work. I'm an engineer by training and so i have the advantage of quite a bit of relevant education background, but I don't have a ton of experience with automotive control systems, and i know nothing about how the spyder in particular is set up. This needs to change before I dive in and start changing things, obviously!

Right now my spyder has almost exclusively suspension development mods. It is supremely capable at autocross and on the track, but I've hit a long-term plateau in the learning curve as a driver. I want more power to make the car harder to drive to its limits, so I can get back on the steeper part of the learning curve slope.

I didn't mean to imply that the computer is using TPS to figure injector duty cycles, just that injector pulse width is a function of more than just load, and many tuner devices are basically defining the word "load" as "injector pulse width."

Questions (all regarding the stock ECU system):

1.) Does long-term fuel trim have any influence over fuel delivery in open loop?

2.) Once the engine is up to temperature, how does the ECU determine when to go into open loop? It appears like it might be a function of load percentage, but is that calculated off the MAF numbers vs rpm, TPS, calculated injector pulse width, or what?

3.) How does the stock fuel pressure regulator work? There seem to be a number of ways of executing a returnless fuel system. In the spyder, is there input from a computer controlling the pump with something like voltage or duty cycle, or is it a mechanical system with a bleed return port in the tank, or what? What I'm getting at is controlling the fuel pressure in some way as one of many tuning parameters. People talk about boosting the voltage to the fuel pump, but all that does is make it so there is enough power to provide enough flow at high power outputs, right? The pressure is independent of pump input voltage?
 

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A couple of good books that ought to resonate with the engineer in you are:
1. Greg Banish's "ENGINE MANAGEMENT Advanced Tuning"
2. Jeff Hartman's "How to Tune and Modify Engine Management Systems"
Really good for building a foundational understanding.
Re your questions part 3:
* How does the stock fuel pressure regulator work? It's a thimble-sized device with an internal spring (pressure relief valve) and is located inside the fuel pump housing (which is in the tank). Fuel from the pump in excess of the set pressure bleeds right back into the tank.
* In the spyder, is there input from a computer controlling the pump with something like voltage or duty cycle? It's just a dumb setup that runs off of the electrical signal it gets, which I believe does not change at all based upon any other parameters.
* What I'm getting at is controlling the fuel pressure in some way as one of many tuning parameters. People talk about boosting the voltage to the fuel pump, but all that does is make it so there is enough power to provide enough flow at high power outputs, right? The pressure is independent of pump input voltage? In order to change the fuel pressure at the injectors you'd need to either modify the OEM FPR to supply a higher pressure all the time, or remove the OEM FPR and make a return system using a manifold pressure-referenced adjustable fuel pressure regulator, which would provide a (relatively) constant differential fuel pressure across the injectors (i.e., pressure to the injectors minus the pressure inside the manifold). Such a return system on a FI engine would increase the pressure supplied to the injectors in accordance with the increasing boost as measured in the IM.
 

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Questions (all regarding the stock ECU system):

1.) Does long-term fuel trim have any influence over fuel delivery in open loop?

2.) Once the engine is up to temperature, how does the ECU determine when to go into open loop? It appears like it might be a function of load percentage, but is that calculated off the MAF numbers vs rpm, TPS, calculated injector pulse width, or what?

3.) How does the stock fuel pressure regulator work? There seem to be a number of ways of executing a returnless fuel system. In the spyder, is there input from a computer controlling the pump with something like voltage or duty cycle, or is it a mechanical system with a bleed return port in the tank, or what? What I'm getting at is controlling the fuel pressure in some way as one of many tuning parameters. People talk about boosting the voltage to the fuel pump, but all that does is make it so there is enough power to provide enough flow at high power outputs, right? The pressure is independent of pump input voltage?
Cap will likely know, but I'll hazard a guess:

1) Yes, absolutely.
2) If it's like most other ECUs out there, it will go into open loop above a certain load (MAF reading) OR in response to TPS above a certain percentage (either). It probably has a set RPM range for closed loop as well, but that's just a guess.
3)Stock FPR is a fixed pressure regulator. The return is at the pump/in the tank, so you're pretty much assured of getting 43-44 psi to the rail. As manifold vac varies, the effective fpr through the injectors varies (psi for psi) - but that's all built into the fuel maps. If you want to control fuel pressure independent of the open-loop maps.... well, good luck with that.
 

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Mike is Correct.. EXCEPT the TPS to Open Loop.. I'll Explain what I know..

I have been learning a few things from an SC member that is running a Smaller than Normal engine in his Track Spyder.. His problem is with the Odd Set up of MAF Housing Size, and Overclocking the ECU to raise the Rev Limit, and the Smaller than Normal Engine, the ECU will NEVER go into open loop. So he is Stuck with 14.7 AFR's on his Track Machine..

I think this is because the Calculated load is not there.. even when the TPS is a Full.. So Proves the TPS is not kicking this ECU into Open Loop..

If you want some Quick HP Fun on your Car.. read this..
http://spyderchat.com/forums/showthread.php?34825-1-and-2-ZZ-ECU-s-Side-by-Side..-Sorta&p=760150&viewfull=1#post760150

I've jumped to the Fun Parts of the Thread..

If you want to try a MAF Spacer and 2ZZ Injectors.. I'll get you a MAF Spacer.. your on your Own for the Injectors..

Cap
 

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Discussion Starter #11
I will check out the book references, thanks.

In our mazda3, open loop is triggered by about an "85 lod" on the OBD2. I'm guestimating 80 in the spyder, but it has enough power so it is very hard to tell (given the horrible lag of the OBD2 output).

I'm guessing "lod" is a function of MAF signal vs rpm with a pre-programmed map for the whole rpm range. Does this seem right?

How much HP can the stock maf in the stock maf tube support before it runs out of range?
 

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Discussion Starter #12
How to force open loop on the stock ecu (speculation):

Cut it off from the O2 data. No data, no closed loop. Downside is a CEL.

Flutter the TPS sensor signal just enough to force open loop. Downside, this gets you some anticipatory extra fueling all the time, but not even " more Extra " when you actually tip into the throttle.

What happens if we lie about the coolant temp? Isn't the load threshold lower and the fuel mix richer when cold under load?
 

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Why do you want to force open Loop?..

Just because it's in Open Loop, does not mean it will jump to the 13's Fuel Mixture..

I like keeping the ECU in Closed Loop.. as by Messing with the O2 Sensor Sig, I can keep the Fuel at 13.5 ARF if I want.. then Snap back to 14.7 for Normal Running.. and then do 15.7 for Hwy Cruising..

Problem with that scenario.. What will do the Switching Between the Various Fuel Mixtures.. Fooling the O2 Sensors is Easy.. Simple Voltage Offset will do that.. But Some Controller must do the Switching..

That is Why I linked you to the Fooling I was doing with the MAF Spacer.. let the ECU do what it thinks it wants to do.. then just mess with the Air Sig to get the Ignition Advanced More.. then Add Fuel Injector Size to Fix the Lean Fueling at WOT..

Cap
 

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Discussion Starter #14
Well, if I lie to the ecu about the actual mass air flow, and then keep it happy with a little bit bigger injectors, I might need to force open loop to keep from getting stoichometric mixtures at higher loads because the ecu doesn't calculate as high a load as it should because it thinks the airflow is lower and the injectors are smaller, right?

That's why I ask about the ultimate hp (or cfm or whatever) capability of the stock maf in it's stock housing....
 

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Going back to square one, it might help to define your situation and goal. I presume that you have a NA 1ZZ, maybe somewhat modified, with an OEM ECU, and you want to be able to tweak the fuel/spark in certain regimes in order to increase the performance (just reading between the lines).
If that's the case, then I don't know of anyone who's more familiar with ways to fudge the stock ECU any better than Cap does.
 

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^^^^^ What he said.

Are you looking for autox class-legal(-ish) short bursts of higher power? Or sustained track power? Or just a little more oomph on the road?

Short bursts of increased power is classic piggyback territory. Intercept the MAF signal, reduce it ==> leaner fueling and increased timing ==> More power but less margin of engine safety (but not that big of a deal when you have 2-minute runs and 20+ minutes of down time).
Do that for 20 minute track sessions and you run the real risk of grenading your engine.
 

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Discussion Starter #17
My long-term goal is an education. My long-term goal for the car is massively more power. Thinking 50 to 100 hp more so than 5-10 hp. My short-term goal is to explore the limits of the stock ECU without spending a ton of money.

One of the pieces I am missing to put together what I have learned so far into something useful is the limits of the stock MAF. I presume it is a 0-5v full scale output? Anyone know what it reads at idle (easy to read_? At WOT+redline+under load (tough without data logging)?
 

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Discussion Starter #18 (Edited)
oh, and the car's present engine setup:

PPE 4-1 medium length header and catted DP (longer tube, smaller primary, larger bend radius header in the garage not installed). Installed for the lack of precats, makes power above 6200 or so. I want power gains from 4k to 6500.

Modified Moroso oil pan

CSP legal windage tray (not installed, probably for sale if someone wanted it)

That's it. The throttlebody coolant loop is still installed. I use Denso filters in the stock airbox, connected to the stock plumbing in the fender. The spark plugs came from japan 62k miles ago. I took them out and looked at them. They look brand new. Back in they went :D

I dynoed the car with the stock oilpan and header at 129.5 peak hp and a nice even 125-ish ft-lb of torque. The same dyno pull showed a terribly rich mix pretty much everywhere like 13.5:1 at 4k and richer as the revs increased, with a small but sharp drop right at the cam changeover. I don't have the sheet anymore, but the SAE corrected peak HP was 125 at the wheels on a dyno that pissed off the guys who wanted to wave the sheet around and brag about peak numbers.

So basically, I have a stock engine on stock engine management. I'm NOT really interest in better fuel economy out of this engine, or tiny transient gains in power. I guess you could say I'm interested in knowing enough so I could build my own piggyback, letting the stock ECU do as much as possible. Not that I necessarily will, but....
 
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