ECUtune Stage 2 version 3 ( 2v3 )
 

We have decided to replace the nitrous oxide tuning software with the much asked for software for using a larger mass air flow meter.

As many of you know, the SVX mass air meter is maxed out at the factory peak horse power and needs to be upgraded if you want to get more peak power than you already have. There is the possibility that this upgrade will improve your performance beyond that of stage 1v4 without any further hardware modifications but this is not yet known. We are not going to do any dyno measurements on our own right away but one of our customers is and we will share that information when it becomes available.

Of course the real impetus behind this upgrade and the reason we've gotten so many requests for it is because many of you do want to do mechanical upgrades to your svx to increase power. This software paves the way for supercharging, turbocharging, and running higher rpms.

Now to the nuts and bolts of it. The stage 2v3 software is the stage 1v4 software further modified to run a z32 mass air flow meter instead of the factory svx mass air meter. Just like the stage 1 software there is a second version of software on the memory adaptor with 5 degrees less ignition advance and without the aggressive ignition advance seek used in the base stage 1v4 software. When power is sent to the input pin of the memory adaptor it runs off of the second version of software. This enables you to run premium unleaded fuel or regular unleaded fuel at the flick of a switch. It also provides a good tune for forced induction.

Here are the particulars on the mass air meters and some of the basics on the adjustments made for the switch. The z32 mass air meter can measure two and a half times as much air as the svx mass air meter; however due to a mathmatical limitation we can only utilize it to measure about 1.9 times as much air in this version of the software. Still that's good for about 440 hp.

The mass air meters give a voltage signal between 0 and 5.12 volts according to how much air is flowing through them. In the ECU software there is a highly acurate table used to translate this voltage into a number used to represent air flow. I'm not calling it an actual airflow measurement because the # isn't in any particular unit for measure of flow and most importantly it isn't scaled to represent the actual airflow yet.
Here is a plot of both translation tables.
http://www.ecutune.com/posts/stage2/maf1.gif

You'll notice there that the plot of the z32 meter is lower than that of the svx meter. That does not mean that it is measuring less air. Remember that all mass air meters measure in a range of 0 to 5.12 volts. The value generated by these curves is multiplied by a constant the size of which varies depending on the flow rate of the mass air meter and the flow rate of the fuel injectors. A higher flow rate mass air meter has a bigger constant. Lower flow rate fuel injectors have a bigger constant. The z32 mass air meter flows 2.5 times as much air as the svx mass air meter and the constant should be made 2.5 times larger when switching mass air meters. Unfortunately with the size fuel injectors we only have enough digits to make our constant about 1.9 times bigger before it maxes out.

Of course we can't have our constant and translation table values not generate the correct #'s so our work around is to use the commutative property of multiplication/division and adjust the values in the translatoin table by the ratio of what the constant would be with the factory 300z translation table and what it actually is in our software. You'll notice not supprisingly that now the curves match up very closely. You'll also notice that while the meter makes accurate measurments on up to 5.12 volts we lost some of the top voltage measurements because now the table values are maxed out. Because of this we are only able to measure 1.9 times as much air instead of 2.5 so we will max out at 440 hp instead of the 575 that the stage 3 software maxes out at.
http://www.ecutune.com/posts/stage2/maf2.gif

This graph shows the comparitive airflow measured by each mass air meter. It shows the value output by each translation table multiplied by the ratio of the constants.
http://www.ecutune.com/posts/stage2/maf3.gif

That about sums it up. The software gives all of the benefits of stage 1 but now uses a z32 mass air meter so that timing is accurately controlled for loads up to 440 horse power and fuel will be accurately supplied to the utter physical limits of the fuel injectors.

Great explanation Michael.

-Chike (now just offer this for the OBDII folks and then we'll be talking... ;) )

Do you have a timeline for when this will be available?
Sounds like a great project.
Already trolling ebay for a used MAF. :D

It's available now. I haven't done a bang up job with the stage 2 page of the website yet but it has been changed to the new stage 2v3.

http://www.ecutune.com/svx-stage2.htm

So do you think we could combine this stage 2V3 with a Apex-i Super AFC and run larger injectors for a turbo (like sti 550s, or even the Q-45 370cc?)

No, you definitely do not want to mess with the voltage signal from the maf meter--that would completely mess up the ignition timing which would be dissasterous. I would first build your system and see if you need additional fuel. I think you will find that if you run a walboro fuel pump the increased fuel pressure and the fuel injectors being able to be driven to 100% duty will give you enough fuel unless you have an engine built to a lower compression ratio. If you need additional fuel then use additional injectors with a seperate controller to add the fuel.

Most people don't have a very thorough understanding of what happens if you go beyond the ability of the fuel injectors to deliver fuel. It's important to note where/when you would actually run low on fuel. When we talk about the size of a fuel injector we are talking about it's flow rate, the amount of fuel over a set time. It's when the time is short for fuel delivery that the injector is most limited in it's ability to deliver fuel. That means high rpms. The higher the rpms the shorter the time the fuel injector has to deliver the fuel necessary for the intake charge in the cyllinder. In driving that means the first place you can expect to go lean is the last place you will find yourself, high rpms at top gear. In the lower gears you will be shifting before you get up to redline. Our shift point is 5600 rpms. 5600/2 = 2800 intake rpms 2800rpms/60sec=46.67 rps 1 sec/46.67 rps = 0.0214 sec per rev = 21.4 milliseconds to deliver fuel. This is quite a bit of time. I certainly wouldn't recomend sacrificing accurate engine managment for 99.9999% of your driving time to get a higher flow rate for high rpms. The stage 2v3 software will run forced induction well--it lights up the tires on our stage 3 system at will. Build your system first after it's running if you find you need more fuel add it without messing with engine management.

Any idea how long it will be till we see some dyno results on this? I'm pretty sure I have a friend that should have like 2 MAF sensors laying around. And depending on how many people are looking for these I may be able to talk to some of my old Z buddies and see what I can do about getting some of these cheap. In case you can't tell I can't wait to get enough money to get my hands on one.

We won't be dynoing the stage 2 code ourselves any time soon. Our demo car has a blower on it which i think would qualify as cheating. Like I said though one of our customers has indicated that he will dyno the stage 1v4 and the stage 2v3 back to back on his car before installing his turbo system. He has a low miles engine and manual transmission so he should get some good clear results for us.

So running a upgraded fuel pump, and running higher fuel presure will be acounted for in the engine managment. I just thought the ECU ran off of a constant fuel presaure and doesnt check up on it, if it were to change.

when will that be happening, any idea?

Possibly discount about the price of dyno costs, if Im willing to do the same thing? :D

Michael,
Based on your understanding on how the SVX's ECU operates, how does it "close the loop" with the injectors with regards to factoring in injector duty cycle and BSFC??
Thanks.
-Bill

This thread finally prompted me to hook up the MAF signal and tachometer signal to my LM-1 data logger. Below are the results for a WOT run that I made this morning on the way to work. The outside air temperature was about 82F, so there was a bit less oxygen than usual. The MAF is peaking right at around 4.5 volts in all four gears. According to Michael's plots, that leaves about 20% headroom for engine mods. But there should be at least 10% reserve for driving in cold temperatures where the air has about 10% greater density. So, realistically, the stock MAF does indeed have only about 10% headroom for engine mods which isn't much (only about 230*1.1 ~ 250 max HP).

http://www.subaru-svx.net/photos/fil...czko/27877.gif

Great plots Mychailo. That definitely explains sheds light on the situation. I couldn't accurately tell from the graphs, but what was the richest afr you saw? Seems like you got pretty rich at the top of 4th gear...

-Chike

Actually 4.56 volts is 86.3% and 4.64 volts is 90.2% of the theoretical max of the svx mass air meter and is only 4 and 3 readings down respectively from the theoretical max--as you can see resolution at this far extreme of the meter is poor. With the z32maf this reading would be around 3.76 volts and lie right in the meaty belly of the curve.

what model airflow meters
 

Well I have access to a few 90-96 maximas and two 94 na 300zxs.Do I have to switch connectors.

No the ECU does not monitor fuel pressure. With the faster fuel pump your fuel pressure is raised accross the board increasing fuel delivery accross the board so that your afr is richer accross the board. At idle and cruise the ecu uses the oxygen sensors to move the afr back to stoichiometric for efficiency. The fuel pressure regulator maintains fuel pressure in relation to manifold pressure. When there is vacuum the fuel pressure is decreased and thus fuel delivery is decreased. As forced induction creates positive manifold pressure fuel pressure increases and thus the amount of fuel delivered increases. This is all mechanical not ecu controlled.

Don't answer my prior question that was answered on your new page,but will I still be able to run a 150 shot with the new software.I understand it retards timing for forced induction,if not I'll just get the software and stick with the two stage zex 125 shot I'm running.

z32 means 1990's 300zx. turbo or na doesn't matter, they both use the same meter.

Hi Chike. The richest was about 11.5:1 in 4th gear. This is pretty much what I observed before. Looking at the MAF reading and the AFR ratio, my guess is that the engine ran leaner in the lower gears because the MAF did not have a fast enough response time. Either that or the inertia of the air in the intake system was not allowing air to get into the engine quickly enough (intake restriction effects).

And as you have a 5spd, the top of 4th gear is around 110mph or so? (basically equivalent to the top of 3rd gear on my 4.44 4EAT)

Interesting to see the afr stays put at 12.5:1 in 1st-3rd gear, and only really richens up a lot in 4th.

Again, great info!

-Chike

Its starting to richen up in 3rd gear too.

is all that up and down gyration in the latter gears an artifact of your logging or real?

The LM-1 has an input signal resolution of ~0.005 volts, and it acquires data at a rate of about 12 times per second. The manual doesn't say how long it reads the signals. I'm reading the MAF signal where it enters the ECU. I'm using a ground wire on the ECU as the voltage reference. I'd guess that the MAF voltage oscilliations are real. Seems to be happening at higher air flow rates. Maybe turbulence in the MAF? Maybe something to do with the MAF response time?

True. What's your mph at the top of 3rd & 4th gears in your 5mt?

-Chike

So you think that this would work well enough for turbo charged vehicle. Do you know what the Fuel preasure would max out at if i were to run 7 PSI.

Well if those are real then there is the explanation of the afr going screwy at high flow rates. A half volt is a lot anywhere but because it's at the top end of the curve that half volt oscilation in voltage is a huge fluctuation in the load reading--25%-30% accross the range where it's happening.

In regards to the above statement Michael, how well would the Stage 2v3 chip work with an OBDI SVX that has an Impreza fpr installed (fuel pressure raised to 43.5psi, instead of the stock 36psi)?

-Chike

I believe 7 psi will raise your fuel pressure 7 psi. Like I said, I'm driving our stage III car on it now and it works fantastically. Our stage III car is probably getting a better bsfc than you will get but it is also putting out more power than i believe you can get from a turbo system. We are running 8 psi which seems to be the most the engine wants to run due to it's relatively high compression ratio. I haven't taken the car to high rpms to see if the fuel injectors can handle it but perhaps you are not getting the full jist of what I am saying by that. Do you realize how fast you are going in 4th gear above 5600 rpms? If you need additional fuel it's not like you will be hurting till you add it. Build the system first THEN if you need additional fuel think about it. I know this is the opposite of what you've heard repeatedly from all the people discouraging everyone from building forced induction systems but now that we've realeased this software things are changed. It is still a major undertaking and is probably best left to someone with some experience or taken on as a hobbyist venture on a spare car but it is now feasible. You won't spend a lot of money and find out in the end it doesn't work because of the ECU. You will succeed or fail based on your mechanics not your electronics.

That's about the same fuel pressure as with the walboro pump so it would be about the same--should work very well for forced induction. It might be a bit rich for a natrually aspirated car. You'll find the afr flattens out very nicely with the z32 meter and our software, richer in the lower rpms (decell is also improved). A naturally aspirated car should run the stock fuel pressure. A car with forced induction should run raised fuel pressure.

I wonder if this would help my situation. My engine won't rev all the way to 7400 rpm. I'm lucky to reach 7000 (w/stage I). When it reaches this limit it starts bucking but not like a normal rev limiter.

My dad's 95 does the same but gets an additional 200 rpm.

In 4th gear I reach 135mph before it starts bucking.

That could just be an inaccuracy in your tach or it could be something else. Subafreak has the same problem but at 6000 rpms and he used to get over 7000. We're trying to figure out what is going on now. He wired his neutral safety switch and switched versions of software around the same time. I checked the version of software i sent him and it has the same rev limit as what he used to have. I have a feeling the different rev limit that different people with manual transmissions are seeing is a result of how they wire up their neutral safety switch and that you may in fact be hitting something else i think i saw in the software. I recall seeing something that looked like a speed limiter around 152 mph from the top of my head. I think you may be hitting that. I don't have a lot of time to spend on it now but my guess is the solution will be to figure out who has the best neutral safety switch wiring and everyone do theirs the same.

My system is wired like a factory 5MT. I know Jesse is missing a few switches.

I know I'm not hitting 152mph :) Highest I've gone is about 145 on the speedo.

I hit the same RPM wall regardless of speed. I have mentioned before that resetting the ECU gives me a couple hundred more RPM for a short while.

I'm not referring to your actual speed. I'm refering to how fast the ecu may think you are going based on rpm and the signals it is getting or not getting from the inhibitor switch. It may not be the speed limit but it warrants looking into. Of course 7000 on your tach may well be 7400 actual rpms or maybe you are right and when you get to the top of your mass air meter readings the engine just doesn't want to go anymore.

Probably the only way to determine this is by measuring the AFR on my car at the limits.

I used to think that the bucking was due the engine hitting redline and the tach not accurately reading the engine rpm, but yesterday, I say over 6500 rpm on the tach with no bucking. In my previous cold weather runs with the air density was higher, I'd be lucky if I got to 6500 before my car started bucking. I'm beginning to think more that the bucking is an artifact of the MAF reaching 4.8 volts. Either the engine is running lean and pulling back timing, or the ecu is cutting spark/fuel when it sees 4.8 volts from the MAF.

Chike, with the SVX, RA 3rd tops out at about 80-85 mph, and RA 4th tops out at about 100-105 mph with a 3.90 axle ratio.

svxsubaru1, If you want to run the stock fuel injectors with a turbo (or SC), you'll have to increase the baseline fuel pressure (unboosted fuel pressure). Otherwise, the injectors will reach maximum duty cycle (80%) at around 250 HP. 7 psi of boost would give close to 350 bhp. To supply enough fuel to the engine for 350 HP, you'll need to bump the baseline fuel pressure up to around 60 psi. Then at full boost, you're fuel pressure will be about 67 psi.

Michael, are you planning to include any sort of afr enrichment changes in the Stage 2v3 chip?

That's the thing Michael, with yor Stage 2v3 software, n/a cars can now achieve much higher hp numbers as their MAF won't be maxed out... (saw signs of my MAF maxing out during my dyno runs last winter when air was a cool 45* in the shop and my only 'power' mod was an STI panel filter).

With the stock fuel pressure and injectors, per Mychailo's post above, at max duty cycle 250hp is the most that can be achieved. I'd just want to be sure that your stage 2v3 software would be adaptable to changes an owner might make over the life of the vehicle (e.g. high powered n/a motor -> forced induction).

I've decided to keep my SVX indefinitely and not get an '05 Legacy GT just yet. However, I'd want to get the most performance out of an n/a EG33 without cracking open the block... ;)

-Chike

Glad to hear you are keeping it!! I guess since you don't leak oil anymore, the car is like new. Or at least looks it!!

Tom

So after my stage III installed what will be left as far as options for me to suck more power out of this beast. Ideally I would hopefully get this heavy tub into the high 11's.

Yeah, but this car is frustrating to make faster. We'll see what the future holds. :) Even an '03+ WRX doesn't look bad at this point... ;)

-Chike

I'd see where you're at after the install. You might be in the high 12's...you might be in the low 13's (maybe higher depending on how heavy your car weighs). Getting to the 11's will take alot more horsepower than the stage 3 is going to provide. Maybe the 'built' low-compression piston Stage 4 motor LAN talks about doing in the future will get you even closer to the mark as you'll be able to run much higher boost than the 7-8psi he's running on his test car.

Going from high 12's/low 13's in a WRX/STI/Evo to the 11's typically takes and increase in those light-weight (3,200lb) cars of around 150+hp at the crank. If you don't believe me, read other boards like www.clubwrx.net or www.evolutionm.net.

-Chike