KA24E Tuning Primer (Rom Tuning)

[Edub1]

So, you are considering tuning your car’s ECU and you want to know where to begin or if you should attempt it in the first place. The first thing you should know is that tuning, while not insurmountable, is fairly involved and one should have a thorough understanding of engine management before beginning. Also understand that there are a few tuning sites with a good deal of info, one such site is http://www.hybridka.com. This is a good place to search for references to existing write-ups or files. A list of links will follow.Once you have decided that you are up for the challenge, the next question is weather you have a DE or an E motor. Fortunately for the DE crowd there is a good base of knowledge and a very user friendly devise called a Bikirom that comes with everything you need to hook up to a laptop and tune away. There are also a number of tunes floating around for this motor. This devise comes with a daughterboard which is soldered into the ECU. There are a couple of very good write-ups with pictures that cover this procedure.

Those of us with the E motor have to deal with a slightly less user friendly situation. Our understanding of the ECU code is not as far advanced as the DE, but progress is being made. To add insult to injury, our ECU lacks consult capability (explained later)

The Board:

E tuning will require removal of a chip in the ECU and soldering of a levered zif socket in its place. The socket will be used to inset an EPROM chip that will contain the tune you design. Once again, pictured write-ups are available.

Burning the Tune:

The chip mentioned above is created with a chip burner. This is a device that can be purchased for about $50 for a serial port type and $80 for a USB type - these link to a computer on which the tunes will be designed. The device comes with the necessary software for the file transfer.

Emulators:

An emulator is basically a chip with a cord attached that links to a laptop and will allow you to tune in real time rather than swapping and re-burning chips. These are nice but expensive.

Tuning Software:

There are a number of free tuning soft wares available. The only one I know of that can currently be used is one called RomEditor. This can be downloaded from the aforementioned site.

Once you have this downloaded, you will need to enable Japanese fonts to get it to display properly.

To use romeditor, you will need two files – an address file (adr) and a bin file (bin). The address file is basically a file that tells the software where everything goes and how to make sense of your bin file. The bin is the tune itself.

To begin, you will click “setup, are crowded reading address file.” Then you will select your address file. Now, select “file, load bin” and find your bin.

At this point I would take some time and get to know the features of the software. Although it is simple software and we are only using a handful of its features there is still too much to go into in detail.

Some key features:

A/F ratio does not work for us.Graphic editing makes things a lot easier to understandFunction, replace VQ map allows instant MAF swapCompare allows you to load another map and compare in graphic view.

Maps:

Notice there are 4 maps entitled “low & high octane fuel and ignition.” The low octane maps are believed to be used in conjunction with the SCV or secondary butterfly valves. This can make tuning quite difficult as the ECU switches from low to high at 2500RPM under load and 3500RPM during cruising. The files I have included disable this function and only use the high maps.

When looking at there tables, you will notice an X and a Y scale – Y being RPM and X being load. The load scale is referred to as TP – it might help to think of it as throttle position although it technically isn't. In the fuel map you will notice some numbers in the high 100s, these are areas of that map that are used for closed loop operation. The others are used to adjust the amount of fuel for the given RPM and load cell. The same is true of the ignition map except it is spark timing rather than fuel.

You will also notice that TP values can be changed. It was previously believed that these should be scaled in the same way K is. This is not the case and these values should be left alone.

K value:

K is a base value used to determine injector pulse for fueling. K is adjusted according to changes in injector size and MAF. A good rule of thumb is to first adjust according to the ratio of old injectors to the new ones, say 270cc/460cc which gives ~.58. It is important to know that the K number is in Hex so a number converter (I use Quick Base) is needed to convert to decimal before doing the math and then back to hex afterward. MAF swaps also involve adjusting your K value. For a Z32 MAF this should be around 2.5. So, .58 (injector) *2.5 = 1.45 – this is your multiplier.

6020 hex = 24608. 24608*1.45 = 35681 = 8B61 in hex.

Mine came to 37800 dec or 93A8

Note this is ballpark. You will need to play with this number until you get it about where you want and then you will fine tune using the fuel map.

Do not try to use idle to adjust K, instead apply light throttle and observe cruising AF ratios which should be between 14.5:1 - 15:1. Light throttle aplication and/or load should put you into the 13s. Idle should be around 16:1 but can be tricky. If you go just a little too lean it will begin to drop into the high 9s or 10s. At this point, increase K 1%-2% or untill it maintains around 16:1. You may also notice that idle tends to drop, this will be corrected by closed loop when you instal your narow band O2 sensor.

As far as I currently know, TTPmin should be scaled according to injector change. From the example above this would be .58

The other values should be left alone at this time.

Timing:

This is straight forward but can be tricky. It is as simple as changing the numbers based on how you want your timing. The trick is knowing exactly where this needs to take place. For a turbo setup you should pull around .75* per lb of boost. Knowing where your turbo will produce boost and how much it will produce at any given point is the tricky part. I chose to avoid this situation and a lot of dyno time by using a BTM which I set to begin pulling timing after 5lbs and then 1* per lb after that.

Tuning:

A good N/A tune can be had by increasing the high load and RPM values by about 5* and leaning out your fuel to 12.5:1. The KA runs super rich in the high load high RPM range. You will need a wideband or some dyno time but it should pep it up quite a bit. Just be aware that this might shorten the life of your cat converter.

Turbo timing has been covered. The correct A/F ratio while boosting is between 11.5 and 11.9 with 12:1 being an absolute maximum. Many people suggest running very rich mixtures in the belief that this cools the intake charge and prevents detonation. While the cooling part is not true, it does decrease the risk of detonation but it does this at the cost of lost power and a mucked up engine. Under extremely high boost levels such measures or water or alcohol injection may be necessary. But, most of us should be aiming for about 11.9:1 and proper timing.

Links:

http://www.hybridka.comhttp://www.moate ... wt...iteup

Hope this helps get things started.

Attachment: EC1.adr (1668 bytes, downloaded 0 times)

Modified by Edub1 at 5:42 PM 12/20/2006

Modified by Edub1 at 5:07 PM 12/21/2006

Modified by Edub1 at 5:12 PM 12/21/2006
Modified by Edub1 at 12:22 PM 12/22/2006

[S13FX]

Now those tunes that we see on hybridka.com for instance like 460cc with z32maf do those have timing pulled in the map? If so how did the person know when to pull timing? Cause it would seem weird to post a tune for everyone to use and not know where to pull timing.

[WDRacing]

Great writeup Eric...I'm going to forward this to the articles forum so it can be hosted in the articles section of Nico as well. Very well done...keep it up!

WD

[turbo2nr]

great write up.

i also recomend going to ecca. and reading the basic of fmu, and enging tuning, its like 15-20 pages each but well worth it, and reallys go indepth about what you mention.

a must for anyone considering tuning their ecu...

i wish some one would unlock a obd2 already and make my like easier..

[Edub1]

Now those tunes that we see on hybridka.com for instance like 460cc with z32maf do those have timing pulled in the map? If so how did the person know when to pull timing? Cause it would seem weird to post a tune for everyone to use and not know where to pull timing.

Good question. I have also found that my super 60 will boost in different places in different gears and at different throttle positions, making it real tough to determine where and how much boost will occur. They are working on converting MAF to MAP to solve this but for now I chose to buy a BTM and let that handle my timing - it eliminates the guess work.

I can also tell you that some of those are base or "example" tunes. I have a tune that works quite well and I've found it to be quite different from what I've seen posted. For instance, mine has stock TP values while those posted scale theirs for injector MAF swap. My car runs like a raped ape.

[WDRacing]

Thats the ***** of a MAF system...timing is so crucial yet such a PITA to get perfect. Not that the BTM is by any means close to perfect, it simply takes the guess work out.

WD

[Poor_S13_Driver]

In a thread awhile back, and i may have even been the one that started it, there was debate about using the BTM some said it was great and someone else said something about that it just plucks timing out randomly. Well it pulls it per PSI so i dont see how that is random. The setup ive been researching for awhile is something like described above. Z32/460cc combo, and a super 60. Basically im still trying to make sure the BTM is a safe way to control my timing. like you said WD takes out the guess work and thats what Im looking for. And some type of chipped tune. (still learning/researching about that) Edub1 are you using SOHC as well? Sorry to thread jack, and i understand if this gets deleted.

[KATwo40]

Thats the ***** of a MAF system...timing is so crucial yet such a PITA to get perfect. WD

This is probably one of the most common misconceptions in the world of DIY tuning.

If I might elaborate a little, without jacking Edub's thread (great wrietup, sir)...

Many people have heard that a MAF system is tuned according to load, not pressure. Therefore, it's difficult to determine the appropriate load cell for different gearing, despite boost levels. However, that's not quite the way it works.

Let's step away from the term "load" and look at it for what it really is. A MAF system is calibrated according to a given weightflow (mass) of air at any given rpm. Period. Forget about throttle angle, boost pressure, gearing, theoretical pulsewidth, etc. Just RPM vs Mass Airflow (hence the name of the sensor).

"Isn't the correction table labeled in RPM vs. TP (theoretical pulsewidth)?" Yes. The TP is a calculation of base injector pulsewidth for a particular weightflow of air. So, effectively, the TP represents air in mass.

Think about this. If you boost 10psi in 2nd gear, the engine ingests less mass air than it would if you were boosting 10psi in 4th gear. Remember, the ECU refers to the correction table to reference a given air mass against a given rpm. So, if the referenced weightflow column (TP) has the correct timing and fueling value, the ECU will always use that value for that particular mass of air, whether it's in 2nd gear or 5th gear.

[WDRacing]

My point is this, with a positive signal from a MAP sensor you can retard timing based on on/off boost WAY easier. Of course a MAF controlled ECU can be tuned, but big HP cars almost always run MAP. I think MAP is the way to go...Speed Density all the way baby!!!

WD

[KATwo40]

Speed density is much easier to tune, I won't discard that.

It really would be cool if someone would figure out how to morph our ECU's into speed density systems.

[WDRacing]

Oh I know how to, I'm just not telling anyone!!! Besides, I don't want to HIJACK this thread anymore.

[Edub1]

This is probably one of the most common misconceptions in the world of DIY tuning.

If I might elaborate a little, without jacking Edub's thread (great wrietup, sir)...

Many people have heard that a MAF system is tuned according to load, not pressure. Therefore, it's difficult to determine the appropriate load cell for different gearing, despite boost levels. However, that's not quite the way it works.

Let's step away from the term "load" and look at it for what it really is. A MAF system is calibrated according to a given weightflow (mass) of air at any given rpm. Period. Forget about throttle angle, boost pressure, gearing, theoretical pulsewidth, etc. Just RPM vs Mass Airflow (hence the name of the sensor).

"Isn't the correction table labeled in RPM vs. TP (theoretical pulsewidth)?" Yes. The TP is a calculation of base injector pulsewidth for a particular weightflow of air. So, effectively, the TP represents air in mass.

Think about this. If you boost 10psi in 2nd gear, the engine ingests less mass air than it would if you were boosting 10psi in 4th gear. Remember, the ECU refers to the correction table to reference a given air mass against a given rpm. So, if the referenced weightflow column (TP) has the correct timing and fueling value, the ECU will always use that value for that particular mass of air, whether it's in 2nd gear or 5th gear.

1 problem with this theory. I have observed that my ecu accesses given cell values regardless of boost levels. That is to say, when I go WOT, I can watch my AF ratios qucikly reach their pre-determined level and then maintain as boost increases. This might be because the ECU quickly finds the last load column based on max flow for our stock motor and stays there ever after. But, it does not need additional cells to calculate AF for more air. For instance, once it finds cell value 49 which means 11.5:1 the ecu will take the MAF value, multily it by 49 and have the right AF ratio for any amount of air so fueling is always perportional to incoming air mass and always held at a given ratio. Another way of saying it is that the ECU say, for RPM Y, and load X use (MAF*cell) and not for RPM Y see MAF and go to load X. Anyway, I've observed that my AF ratios find the correct spot on the map and maintain AF regardless of boost level. I've ran 0lbs - 17lbs on the same fuel map and found no change in Af ratios - this confirms my theory as otherwise AF would change dramatically. WOT is ~11.5 regardless of boost level. It does follow my throttle position almost like clock work even though everyone says not. Perhaps it follows it untill it tops out and then just keeps calculating based on that value and MAF.

As for timing, I assume the same is true. However, there are simply different boost patterns for different gears. I can boost to 15lbs at 2700RPM in 3rd but only be at 5lbs at 3500 in first. Likewise I can see boost in high RPM under light throttle too. So, do you pull 7* at 2500 RPMs and back of to stock at 3500? Obviously that doesn't make sense. And this would hold even if load is determined by MAF readout.

I've also found that changing to higher TP does nothing. The ECU looks where it looks.

[KATwo40]

This pushes me toward a standalone even more.

[S13FX]

Pfft with the gizmos that are coming out here recently that Iv been looking at, Standalones are pretty soon going to be only considered by the hardcore tuners.

Something I have been lookin at here will alow for me to not even worry about timing at all, and just use a afc for afr correction. Also with running E85 Timing is going to be the least of my worries. Only thing I see my self using a rom tune for is if I need to make the ecu think that for instance 550cc injectors are stock, because since E85 requires 30% more fuel and the safc only goes +/- 50% the ecu set at 270 would be screwing everything up.

But stay tuned that is tottaly another subject. And what everyone is saying about MAP is very true and I tottaly agree, but why not work with what we got, how many people here are acutually going to be running more then 400rwhp. I mean look at the recent posta on this board seems like we only have a hand full of people that are actually going above the 350 mark.

And Edub that is a freakin great write up, Rom tuning FTW if your using a SOHC in my opinion.

[Edub1]

Thank you. It's not that bad once you get in there and get your hands dirty. I also found that keeping closed loop and using a good O2 sensor takes care of rough idle problems.

For 550cc Z32 MAF I'd start with

K=75F8VQ switched to Z32TTPmin scaled by .49 TP values left alone. Fuel map boost areas set around 47-49BTM for timing.

[Edub1]

Oh I know how to, I'm just not telling anyone!!! Besides, I don't want to HIJACK this thread anymore.

I hate to give away your secret, but...

You can use a trubo Sunbird ECU to make a budget speed density ECU that handles up to 3bar of boost.

[SSS]

Gabe (deviousKA) is working on a full MAP conversion for the SOHC ecu. He already has the timing controlled by a MAP sensor input.

[S13FX]

REALLY WOW GO SOHC. I wanna test it out I wanna test it out. Hmm I wonder how this type of setup will work with my E85.

[WDRacing]

I hate to give away your secret, but...

You can use a trubo Sunbird ECU to make a budget speed density ECU that handles up to 3bar of boost.

Thats actually almost exactly what I was talking about...LOL. I didn't know there was a turbo option of the Sunbird...what turbo does it have, probably tiny??

[Edub1]

Gabe (deviousKA) is working on a full MAP conversion for the SOHC ecu. He already has the timing controlled by a MAP sensor input.

Is that why I couldn't get the EC3 code to work right?

[Edub1]

Thats actually almost exactly what I was talking about...LOL. I didn't know there was a turbo option of the Sunbird...what turbo does it have, probably tiny??

I'm not sure of the turbo size but the ECU is universal and can use up to 3 bar. The guy who turned me on to it said they have been using it on Mustangs and all sorts of things. Best thing is that someone leaked GM's code so everything about the ECU is known. I have the part number and all the stuff for Tuner Pro. It really is like a stand alone. Only thing is it's speed density which I hear is a step backward from a MAF system.

[KATwo40]

I'm not sure of the turbo size but the ECU is universal and can use up to 3 bar. The guy who turned me on to it said they have been using it on Mustangs and all sorts of things. Best thing is that someone leaked GM's code so everything about the ECU is known. I have the part number and all the stuff for Tuner Pro. It really is like a stand alone. Only thing is it's speed density which I hear is a step backward from a MAF system.

Care to email me a little more elaborate info on this ECU?

Also, speed density is the most common high performance tuning platform. As WD stated, it's much easier to tune for specific boost pressures.

[WDRacing]

SPeed Density rocks, anyone who says it doesn't shoudl simply look at all the really high hp drag cars in the import comunity. I don't see GTR's running MAFS, Supra's running MAFS...I could go on. MAF is not a bad thing. Its got benefits, but for tuning and WHP, SD is the way to go.

WD

[KATwo40]

Not to mention F1 cars, GT series cars, Indy series, etc.

[Edub1]

Perhaps I should have listened to the guy when he told me to do the swap. Oh well, I'm plenty happy with my tune.

I'm going to try to post the xdf file and a bin. You might hae to search to find which ECU it is but it's used on a few GM vehicles such as the Turbo Sunbird and the Cyclone truck.

Well, I don't see the ability to attach files here. I think I got the stuff from boostcruising.com

[Thursday]

Thats actually almost exactly what I was talking about...LOL. I didn't know there was a turbo option of the Sunbird...what turbo does it have, probably tiny??

Funny you ask, I ran this turbo on my old civic, it has a garrett tb25, same downpipe flange and exhaust flange as an sr t25g, but the tb25 is a bit smaller with a .48 a/r on the very different compressor housing.