How to tune your 3/S using Chrome and a Flash ECU

Disclaimer: I have used the method outlined below successfully to tune my car. I am an amateur and not a professional. If you use this method then you accept full responsibility for whatever damage you do to your car. If you are concerned about damage to your car, you are better off leaving your car without any modifications to the ECU.

I am writing this essay because I often see a lot of request from 3/S owners on how to begin flash tuning, what equipment is needed for accurate tuning, what approach should I take to tuning, etc….

All the info in this particular thread only pertains to Chrome V2. As I release future chrome versions, I'll be frequently come back to this thread and updating it.

NJ1266 from EVOm posted a thread like this over there and did an excellent job. Much of what you're reading here will derive from his thread and is adapted to Chrome. Full credit for this essay is given to him!

Aside from the equipment and approach, the two most important elements to have are PASSION and TIME. If you want to learn how to flash tune your car simply to make money out of tuning, then IMO you will suck at it. Passion should come first and making money out of tuning is a distant second. If you do not enjoy tuning, then do not do it. You will end up very frustrated and maybe mess up your motor.

The second important element to learning how to tune is TIME. You must read a lot and test a lot. The best place to visit and read is the Ecuflash forum on Evom. This is the hub for Ecuflash tuning. I spend hours reading threads over there…. Some of the stuff that I read is highly technical to me. I get confused, so I read and re-read and read again. Sometimes I read threads three to four times before the concepts sink in. I get very frustrated at times since it's such a different concept than what most are used to. Don’t be afraid to ask questions but please don't PM me. Start your own thread or post in the linked threads from the Tech Manual! If you are polite and have done your reading prior to asking your question, then I will be a lot more inclined to help you.

When you first start reading you will be confused. The learning curve is steep and the task seems daunting. There is simply too much to read. Some of the posts are top notch and some are pure crap. You will have to figure out which posts to believe in. But do NOT give up, persevere. You CAN do it. It is NOT hard to flash tune your own car. It is not black magic or rocket science.

On the opposite end of the spectrum, there are people who have this strange delusion that the Chromed Clone ECU is some simple plug and play affair which doesn't require any tuning at all. Nothing could be further from the truth! Chrome comes with all 100% stock tables for an American spec 99 VR4. If you car isn't a 100% stock 98/99 with 3 cats, stock MAF, stock exhaust and all emission equipment, then some changes need to be done. While the closed loop feature of the ECU is very good at compensating for many of these changes, it'll really only get your motor to start, run and cruise. That's about it. Don't believe anyone who tells you anything different!

If you have PASSION and TIME, then the next step is to get the best possible equipment that you can afford. So what will you need?

You WILL NEED a VR4 or Cloned ECU to utilize all the features of my patched ROM.[/B] If you're using another ECU other than the VR4 ECU (Montero, Diamonte, SL, Base...) some features will not be available. Fortunately there are guys who have been working on Cloning the VR4 ECU!

More info here!

www.clonedecu.com

www.chromedecu.org

You need the following:

1. Laptop: You must have a laptop. Modern tuning is all about computers. W/O a laptop, it is very hard to tune accurately with consistent repetitive results. There are many cheap used laptops on ebay. Make sure that you get one that is powerful enough for your tuning needs. I also recommend that you get a small laptop with a small screen. Mine is bulky and has a 17 inch screen. I am now in the market for a very small 7 inch mobile computer.

2. Logging hardware: You will need a logging/flashing hardware cable. The one that all of us currently use is the Tactrix Cable (http://www.tactrix.com). DO NOT BUY THE 1.3 CABLE!! We need the power booster from the 2.0 cable for flashing.

3. Wideband O2 meter (WBO2): Do not attempt to tune your car if you do not have a WBO2 meter. Do not use the narrowband O2 sensors to tune the car. The NBO2 was not intended for tuning purposes. It is used for emissions and it is only accurate under stoichometeric conditions and even then it is barely accurate. Logging them only tells you if the ECU is in closed loop or not.

Tuning with a NBO2 was used back in the DSM days when WBO2 were very expensive and no one could afford them. Today, you can get a WBO2 meter for as little as $180. I use Innovate products. I have an LC-1 wired directly into pin 93 of the ECU. More details into setting this up later.

4. Logging Software: The most widely used logging software is Evoscan (http://www.limitless.co.nz/EvoScan). It uses the tactrix cable to log data from your ECU port. It also allows you to integrate data from your WBO2 with the data from your ECU port. It costs $25. It is a one time fee that entitles you to later updates of the software. It is very user friendly and easy to set-up. After you purchase, download and install EVOScan, you'll need to add my custom 3000GT log file. NO other logging program available will support my patched ROM.

5. Tuning Software: The tuning software is known as Ecuflash. It is for free and you can download it from http://www.openecu.org.

6. Chrome V2: Unlike V1, I won't be releasing different patches for different setups. There is 1 universal ROM now which can be tailored to your needs.

Go to here and download the ZIP file.

www.clonedecu.com

OR
www.chromedecu.org

http://i.imgur.com/2RRZN.jpg

Inside is a folder with 3 files inside. One is the Chromed ROM (.bin file), one is the definition file for the ROM (.xml file) and the other is the definition file for EVOScan. All 3 are tied together and are meant to be used in conjunction with each other. You'll find many of the features in these definition files won't work with a stock ROM or previous versions of Chrome.

Extract the 23862006.XML fileto:
C:\***File Folder you installed EcuFlash***\EcuFlash\rommetadata\mitsubishi

The 23862006.bin is the ROM itself. This is the file you modify & flash to your ECU. Extract this anywhere you'd like. It doesn't matter where you put it, what you name it or how many copies you make of it. It will always reference the 23862XX6.xml.

Finally, the Mitsubishi MUTIII 3000GT.xml file is the definition file to convert EVOScan to work with our cars. Extract this file into:
C:\Users\USER\Documents\EvoScan v2.9\DataSettings

http://i.imgur.com/PLmII.jpg

Note: Sometimes there's an issue with installing ECUFlash/EvoScan. Windows 7 and Vista have a feature called UAC. It makes a duplicate copy of your program files. This means when you try to install the EvoScan and EcuFlash .xmls, the changes won’t take effect, instead the duplicate .xml will be used

Try this! Uninstall EVOScan and ECUFlash and don’t reinstall them in C:\Program Files. Instead install to another directory created by you. For example C:\ECUPrograms\

After EVOScan is installed, you'll need to install the 2.0 cable drivers. There are instructions on the EVOScan website for this.

Now open up ECUFlash and open the 23862006.bin. This file is a stock tune for a 99 VR4. If you've flash tuned your car before, you'll need to copy your tables to the new "Chromed" ROM. Sorry. :( I can assist with this if needed. It's a good idea to save this file under a different name. It'll still be linked to the correct definition file no matter what you name it or however many copies you make of it.

So now that you have all the equipment and tools, what do you do next?

First, you must install the WBO2 properly. DO NOT install the WBO2 sensor behind the Catalytic Converter. That will give you erroneous AFR readings. The best position to place the sensor is in the down pipe 2 inches before the flange in the three o’clock position on the passenger side. Do not place the sensor in any position below three o’clock. You do not want condensation to form on the sensor and destroy the sensor.

After the sensor is installed, you can wire the 5V output into pin 93 of the ECU. This pin was never used on the 91-97 cars so it should be open on your adapter harness. Brett will populate this pin with a wire for you to hook up with if you request it at the time of ordering your adapter harness. Brett is also willing to sell the pig tail with the individual pin if you need it as well.

Installing pins is easy. The pins come out of the stock wiring harness by unhooking the little cover that holds a row of pins in place. Then all you do is push the pin into the correct slot in the harness plug.

If you mess up and put it into the wrong slot, you need a tool that goes around the pin to depress any tangs that stick out from the pin which help hold it in place before being able to pull it out. A jewelist's flat heat screw driver, a paper clip, even a bobby pin work for this.

This is a great video on how to remove/install pins. The only thing left out from this video is removing the locking cover from the back side. I'll get pics of this soon!

http://www.youtube.com/watch?v=LLKn_5Wqs8g

Pin 93 is shown in this diagram.

http://i.imgur.com/OBuly.jpg

One last bit before you can log the wideband is to scale the wideband table to your particular sensor voltage.

http://i.imgur.com/xSI5E.jpg

The left hand side of the table is the sensor voltage, the right hand side is what AFR value corresponds to that voltage.

Both AEM and the LC-1 list their particular sensor voltage in the instruction manual that came with your gauge. You can also find them easily online.

Note: you can edit both columns in the table to match your sensor.

In EVOScan, in order to log the wideband you must use the Wideband Scaled request:

http://i.imgur.com/Vyred.jpg

Optional:

You can also install a 5V map sensor for logging boost into pin 92. A MAP sensor is usually tapped into the little hose that connects from the back of the intake manifold to the FPR solenoid on the firewall. That is the way it reads pressure. The pressure pulses are translated in the sensor into 0-5 volts signals and sent to the ECU. The data logger takes the signals and based on the calibration data that you supplied translates the voltage into psi.

One method to log boost uses the GM 3 Bar MAP sensor. This sensor is widely available and very easy to set up and use. I recommend 1G guys use this. I bought mine with a pig tail harness for $75. If you're really nice, Brett could be talked into supplying this with his ECU adapter harness too. ;)

Like the wideband, you must set it up using the calibration data that was provided by the manufacturer. The calibration data for the scaling table is as follows:

Volt --------- PSI
0.000 ------- (-14.7)
0.631 ------- (-8.9)
1.134 ------- (-4.4)
1.600 ------- 0.0
3.884 ------- 20.1
4.914 ------- 29.4

Another method to log boost is to use a EVOX MAP sensor. This is the sensor I recommend for the 96+ cars as it literally plugs right into the stock harness and manifold! No mods even need to be made to the adapter harness!

More details on setting up the EVOX sensor here.

http://www.3sgto.org/f104/disassembl...nsor-8260.html

Note: You can use either the GM or EVOX or any MAP sensor in any car. My suggestions are based purely on installation simplicity.



***optional Clutch switch install***

This setup is only needed for the Clutch In rev limit (NLTS) feature and fuel pump on clutch chrome mods. It's very simple. Cut the wire for pin 67 of your ECU adapter harness. That pin should be populated and do not tap it! Now extend the ECU side of the wire you cut to reach all the way over to the cruise control power kill switch (easier one to access) or the starter interrupt switch. This involves crawling under your dash and tapping one of the two wires (do not cut it). I can't remember what color wire it is you want to tap but it's the side that does NOT go to chassy ground.

Again, I'm sure Brett can be sweet talked into including a wire for this with this ecu adapters.

*picture coming soon!

First thing you must edit in the ROM are the periphery bits for your car. This is most important for the OBD1 (91-95) cars. When V1 first came out, there were still a few of these I didn't quite understand (especially in periphery 0). This area of the code probably took the longest to disassemble and Jeff deserves major credit for his help in tracking down which bits correspond to what CEL.

Basically, Periphery 0 is just a bit to toggle specific OBD2 functions and Periphery 2 thru 4 just toggle individual Check Engine Lights. This is Periphery 0:

http://i.imgur.com/TSerT.jpg

When you install a flash ECU into your car and/or you want to do a full vac reduction, there aren't any bits that need to be disabled in this periphery.

The only thing you might want to play with are the Speed Limit Function (bit 6). This enables the safety feature. Handy for when you drop your car off at a shady mechanic and you're afraid they're gonna play with your car. ;)

If you want your car to run only on 1 narrowband instead of 2, disable bit 2. This will then make the code function off the rear narrowband only.

If you want to disable closed loop entirely for any reason, switch bit 4 off and the ECU will be in open loop all the time.

Also note that I made mention to not play with bits 11 or 12. This is because they don't enable/disable the code, they only switch the code to another type of function. Since Mitsu used this ROM in every one of their vehicles, they encoded the functions for all the cars and used these bits to trigger which condition they wanted the system to function under. If you play with these, you'll find your car will run like ass.

Leaving these as they are and eliminating the solenoids will not hurt anything.


This is Periphery 1:

http://i.imgur.com/MWQwr.jpg

AKA the Chrome Mods periphery. I took it over as it was all just unused space in memory. I've also included a switch bit to disable all the mods at once for diagnostic purposes should you run into issues.


This is Periphery 2 thru 4:

http://i.imgur.com/U8g12.jpg

These are all the CELs I could find in the code. Quite literally all you have to do is disable the bit containing the code you don't wish to see illuminated on your dash.

So when you first install your Flash ECU, you'll need to disable bits 15, 14, 13, 11, 10, 9, 3 and 1 to ensure no CELs if you're a 1G car (or any car with a full vac reduction) without any of these systems. Even the 96/97 cars will need to disable bits 13-15 as you guys don't have the same purge system as the 98/99 cars.

Say you wanted to eliminate the secondary O2 sensors without a CEL. Then all you gotta do is disable bit 3 and 11. See how that works?

Disabling these bits won't disable their function, only the Check Engine Light!


All 3/S came with an EGR and purge system. Functionality of both these systems is still tied into Chrome, however, the OBD1 cars (91-95) cars have a different setup for the purge. The stock boost and EGR solenoids are PWM on all year cars so nothing needs to change with them.

More info on the EGR:
http://farnorthracing.com/stealth/AEM_Mitsu_EGR.htm

Special thanks to Dennis for the link!

The purge is switched on when driving with a low to medium load on the engine, the fuel vapor absorbed by the canister is drawn into the P port of the throttle body in the same way as in engines without turbocharger. When driving with a high load on the engine, the purge control valve opens and the fuel vapor absorbed by the canister is drawn into the air intake hose.

In the OBD2 cars, they redesigned the purge system a bit. Instead of an on/off style solenoid, they switched to a pulse width modulated (PWM) type solenoid. If you have a 96+ car and wish to keep the purge system, you don't need to change anything.

If you have a 91-95 car, there's a couple options available. You can swap the purge solenoid for a PWM solenoid (the stock boost solenoid is an option) and it will function like a stock OBD2 car. If you'd like to keep the simple on/off style solenoid, use one of the Chrome Custom Pin Outputs to operate the purge solenoid. You'll need to swap the ECU pin on your adapter harness.


***optional EVO MAF install***

The ECU calculates airflow starting with the MAF Size and the MAF Pulses. Being able to read this number accurately is advantageous over the traditional boost gauge/butt dyno as you're able to see if your airflow numbers go up with each mod performed. When you get to the point where you keep raising the boost, but airflow isn't increasing, then you hit the limit of the efficiency of your turbos on your particular setup. There's a MAF Pulse Limitation in the code. This isn't a physical limitation of the MAF itself, just an issue where the ECU will stop adding fuel past a certain PPS (Pulse per stroke) due to a 1 byte limitation in memory. Beyond this limitation, the ECU will stop adding fuel so be forewarned.

This limitation is 13.06 PPS or 319.7 grams of air/second (table is shown in the V2 xml). With a stock MAF, this is only about 450hp depending on which HP calculator you're using. This is coincidentally is about where the stock 3/S MAF also seems to run out of resolution. Thought that was interesting. Obviously the car is capable of making more power as people have been doing so for years by fooling the ECU into seeing less air with a piggyback.

The EVO MAF won't pulse as often for the same airflow as the stock 3/S MAF so this is the current method for getting around this limitation. Wouldn't be surprised if the limitation is double the stock 3/S MAF. When you install an EVO MAF, these are the settings you need to make your tables. Leave everything else alone.

http://i.imgur.com/laCsg.jpg

JestersDeadd is currently selling EVO MAF intake adapter kits for the 3/S! Details here:

3000GT/Stealth International Message Center


***optional Throttle Body Replacement***

All our cars are approaching the 15+ year old mark. The throttle body is the crucial part of the engine which regulates idle and cruise operations. 90% of all issues come from sensor failures, clogged FIAV and leaking BISS and throttle plate screws. To compound the issue, nearly every car gets this oil muck saturated within the small chambers within the throttle body which impact airflow. I'd highly highly HIGHLY recommend you get it replaced with a NEW unit from mitsu, or contact April to get it rebuild. She does great work rebuilding our throttle bodies!!

http://www.3sgto.org/f62/throttle-bo...ice-10630.html

After you get your peripheries setup, the next thing to do is get your injectors setup.

The stock injectors are rated at 360cc/min. Generally speaking, the stock injectors will give you adequate fuel flow with a TBE, an intake, and 14lbs of boost. Once you get bigger turbos, then definitely get bigger injectors.

If you install bigger injectors, then you will have to scale them properly and use the correct injector voltage latency. In the Fuel Section of Chrome, locate the Injector Scaling table and the Injector Battery Voltage Latency table. Injector Latency scaling equation is a function of the Injector Dead-Band Coefficient. There's no need to modify this value. It's needed for figuring out which Latency Scaling the table lookup value is used.

http://i.imgur.com/gVWxQ.jpg

Setting the scaling is simple. Just enter the rated size of the injectors you are running for pump gas. If you're running E85, take the rated size and multiply it by .7 and use that number. This will add 30% enrichment needed for burning alcohol.

The latency (aka injector dead time table) requires a little bit of research. The numbers in the right column are in milliseconds. The numbers refer to the amount of time that the injectors take to open completely and produce maximum flow. The numbers in the left column are in volts. As battery voltage decreases, the time between the injector receiving the signal to open and when it actually opens increases. Therefore, you must send the signal sooner to have the injector open at the appropriate time. The larger the injectors, the more time is needed for them to open. So you will have to increase the numbers in the millisecond column to compensate for larger injectors.

This table is a great reference for dead times!

Fuel Injector Lag Time

Note: You can rescale the voltage side of the table to match the chart if you please.

After you have these 2 tables set for your particular injectors, you can forget about these tables. This should be adequate to get your car to start/run/drive. The EVO guys like to fine tune their cars by playing with these values. I've come up with a much much simpler method for tuning.



Before we go any further you need to understand the closed loop feature of the code. Jeff L has a great description of what this is:

Stealth 316 - 3S Fuel Injection Control and Fuel Cut

Quote:

---

Originally Posted by Stealth316

Closed Loop Control (Feedback Control)
In closed-loop mode, the ECU is using oxygen sensor voltage (see figure above) in a feedback loop to restrict the air-fuel ratio to a narrow range where the catalytic converter is most efficient. That range is A/F equal to 14.7 plus or minus 1% air (0.99-1.01% lambda, where a theoretical lambda of 1.0 equals an A/F of 14.7), or ~14.55 to ~14.85 A/F. The oxygen sensor indicates a (theoretical) stoichiometric air-fuel mixture (A/F equal to ~14.7) with a voltage typically in the range of 0.45 to 0.5 volts. When the sensor output is greater than this range, there is much less oxygen in the exhaust gas than in the atmosphere and the mixture is rich (A/F is less than ~14.7). When there is excess oxygen concentration in the exhaust gas, that is, as the oxygen content approaches that of the atmosphere, the sensor sends a signal less than 0.45 to 0.50 volts to indicate a lean mixture (A/F is greater than ~14.7). If fuel injection is stopped in the engine, oxygen content in the exhaust stream will equal that in the atmosphere and the O2 sensor voltage output will be zero. Typically the ECU uses a reference voltage of about 0.4 V, which is just on the lean side of ~14.7, or a lambda ~= 0.995. The ECU reacts to these rich and lean signals by reducing and increasing, respectively, the injector activation duration. By using this feedback control to maintain the oxygen content in the exhaust stream within a very narrow range, the three-way catalytic converter operates at its peak efficiency to reduce carbon monoxide (CO), hydrocarbon (HC), and nitrous oxides (NOx) emissions.

Closed loop mode is used generally during warm idle, low-load cruising, and low-load acceleration to reduce engine emissions. Best fuel economy actually occurs with a slightly lean mixture, with A/F a little more than 16. Despite the need to reduce emissions, there are certain operating conditions where closed loop mode is not used in order to prevent overheating the catalytic converter or driveability problems. These situations include:

While cranking the engine.
During engine warmup when the coolant temperature is below 45ºC (113ºF).
During strong acceleration or deceleration.
During high-load operation.
When the oxygen sensor is not functioning properly.


Open Loop Control (Preset Map Control)
In open-loop mode, generally during moderate-load and high-load acceleration, the ECU is not using the oxygen sensor information and instead relies on preset maps stored in ROM (read-only memory). These maps use engine speed and A/N to modify the basic injector activation time toward a target A/F. A/N is equivalent to engine load and is the amount of intake air into each cylinder per engine revolution. As mentioned above, correction factors are applied to the map-adjusted drive times. Using information from the wizards who de-code the DSM ECUs, our 3S ECU, which has similar programming, will select open-loop mode regardless of engine load when the following occur.

---

Basically, closed loop is an "auto tune" feature of the ECU. In the code it takes whatever HZ pulse value it gets directly from the MAF and multiplies that by a percentage before continuing on with its air mass calculations. It's a handy feature which aids a lot in handling the "age factor" of your engine or compensating for a poor tune you flashed onto the ECU. ;)

For a given RPM the ECU looks up both a minimum engine load and TPS. When both conditions are exceeded the ECU goes into open loop. There are 3 Load conditions. I'm not yet sure what factor the ECU uses to switch between the first two tables, but the 3rd table is used during warm up when the engine coolant temps are less than 140 degF.

The Load Inhibit table is just a reset value in a sense to re-enable closed loop when the ECU doesn't detect a change in load anymore. There's really no need to edit these tables.

http://i.imgur.com/oq0FJ.jpg


First Flash

At this point you're ready to flash! Read this:

People need to be aware of the risks when flashing as bricked ECUs from low battery voltage is starting to become a common enough of an issue where the importance needs to be stressed. Guys should turn their stereos, headlights and AC OFF when flashing to ensure as little draw on the battery as possible. It's best when flashing your ECU for the first time to have a battery tender hooked up to ensure there's no voltage drop during flashing!

Quote:

---

Originally Posted by Jeff V.

This cannot be stressed enough! I used to work at a General Motors support group, and the only function of my group was to support vehicle reprogramming and the related tools. There were pages and pages of dealer bulletins related to voltage while programming. They even started requiring the dealers to buy a special $300 battery tester/charger/maintainer for use while programming.

They had to buy this tool not because the technology sucked, but because the damned techs wouldn't follow the rules while programming. Then, rather than call us to see if the module could be recovered, they'd just warranty it and sometimes make the customer wait for a new part.

Doesn't matter if it's a GM, Mitsubishi or BMW. If you follow the rules, it will work every single time.

---

I've posted up "how to's" in the past but the absolute best resource for learning how to use ECUFlash and EVOScan are on EVOm. Even though these threads/videos are based on the EVO, the 3/S shares many similarities.

Must Read before using software!
Can't flash/read Rom? Start here!
ECUFlash/EVOScan Training videos

http://www.youtube.com/watch?v=qVtOSzzvF_g&list=UUHysplPp9tIb6h-0hFwfIUw&index=4&feature=plcp

These links should contain most of the info you need to know. Of course I'm available to assist with any questions you may have, but keep in mind, I can't educate every single person individually. There's no such thing as a stupid question but it's ridiculous to have to answer the same questions that are already answered in the links above. Even so, I will do my best to help where I can. :)

Take your time to read and learn all this!

Note: There's really no need to read and save the ROM flashed onto your Cloned ECU when you first receive it from Adam/Brett. We are discussing maybe selling these ECUs with V2 already pre-flashed with the stock file included so you can go ahead and flash your base tune when you have it setup.

Logging

Next, after you flashed your ROM to your Clone ECU, you have to go out and log data. You must log, log, and log some more. First you gotta configure EVOScan to use the 3000GT.xml file and don't forget to set the injector scaling to match the injector scaling you're using in your ROM. This is important for EVOScan to give you accurate IDC readings.

http://i.imgur.com/PLmII.jpg

Only log the essential data with Evoscan. Logging all the data from your ECU will slow your logger down. You must study and understand what the data means. These are the essentials:

http://i.imgur.com/yNIfv.jpg

A handy feature of 2.9 is the "Display Selected Items Only" check box which hides all the Requests you don't have checked. Really cleans up the list from the data you don't want to view.



Tuning closed loop/fuel trims

Before you can proceed to modify the tables in your rom, the most important advice I could give you is to work INCREMENTALLY. Make small changes to the tables.

For example, in the high octane fuel table lean out the map by making changes of no more than 0.3-0.4 target AFR. Do not go too aggressive in your changes. Another important piece of advice is to make the changes SMOOTH between cells. Recently, I saw a map that had the target AFR jump from 10.9, to 9.4 in two adjacent cells in the fuel map. This same map had a timing jump from 9* to 13* from 6500 to 7000 rpm. . The lack of smoothness in the map transition will more than likely trigger knock. A 4* jump from one load cell to the next will more than likely trigger knock on 91 octane gas.

So which part of the ROM do you start tweaking first?

You need to make sure that the numbers that you have entered for the fuel injectors (and optionally the MAF) are working properly. To do that you MUST log your fuel trims for an extended period of time. The trims to log are:

LTFT Low = Long Term Fuel Trim Low (front and rear)
LTFT Mid = Long Term Fuel Trim Mid (front and rear)

Note: The high trim is almost never used as typically you're in open loop by the time you get into that airflow range. NA cars don't even have a high fuel trim
Note 2: The ECU only modifies the trims while in closed loop, however be aware even in open loop, the fuel trims are still applied!

Both of these trims fluctuate between +/- 12.5%. The LTFT Low is for idle and the LTFT Mid is for cruising. Your aim is to keep both trim to +/- 5% or less. If the fuel trims are too positive, then the ECU will add fuel and this will royally make your AFR too rich. If your fuel trims are too negative, then the ECU will remove fuel and this will make your AFR too lean.

The Fuel Trim Range table is simply a percentage modifier to the raw input HZ from the MAF. Much like an SAFC actually. This table differentiates between the 3 trims. As it turns out the enrichment/enleanment factor from your fuel trims are still applied even in Open Loop so it's best to try to keep those trims as close to 0 as possible while tuning. This is the table which tells the code which trim to use.

http://i.imgur.com/rXl1E.jpg

I've never really needed to modify this table but I suspect a tweak may be needed on a car with large cams installed.

Logging fuel trims takes a lot of time and you will waste a lot of gas to get your fuel trims as close to 0 as possible.

Starting with the LTFT Mid. You must drive the car at a steady speed for at least 16 minutes. Why? The fuel trims cycle approximately every 4 minutes. You will need to have them cycle multiple times until they settle on a number in your log. 16 minutes will alow your trims to cycle 4 times. That will give them ample time to settle.

The LTFT Low is mostly applied during idle. You must let your car idle for quite a while to get this trim to settle. Be aware the any vac leaks and FPR over run effect this trim greatly!

Note: It's normal for the front and rear trims to not match. Don't sweat that too much.


What is volumetric efficiency

After a couple weeks of driving your car, if your trims are still within that +/- 5 range, you're good to go! If not, you gotta do some fine tuning. I need to explain something called Volumetric Efficiency. VE is the measurement of how close the actual volumetric flow rate is to the theoretical volumetric flow rate. An engine has a set volume (displacement) that can be calculated. However, your engine will not use the full volume (100%) it has available because of friction losses, leaks, and the fact that a mass produced engine can only be so good before the money out weighs the benefits (the point of diminishing returns). Turbos completely change the game entirely as now you can force an engine to be much more efficient by blowing air thru it.

A grease-covered, wrench-turning monkey like yourself cannot have your car operating at less than par performance. So you "have" to go out and buy aftermarket induction parts, a set of ported heads, bigger turbos and a good exhaust system. It is all in the name of automotive science (at least that is how we explain our addictions to our better halves). All of these parts help to increase the volumetric efficiency of the engine and bumps up the power output of the car allowing you to edge ahead of your racing buddy.

The Code is tuned for a stock motor's efficiency using this table here:

http://i.imgur.com/XSo98.jpg

This is the table you will become intimately familiar with tuning over playing with values in the fuel table. As you get this table fine tuned with your car, you'll find that your wide band AFR readings will match the fuel table almost perfectly! The left side of the VE table corresponds to the input signals from the MAF and the right hand side is a correction multiplier applied to the air volume calculation. As you increase the numbers on the right side of the table, you tell the ECU to add more fuel. Lower numbers mean less fuel.

So going back to the logs you took of your car, observe the 2 byte airflow values and what they did with the trims. Remember the low trim is 94 HZ and below so if your low trims are negative, you need to take away from the numbers in the 100hz cells and below. If they are positive, you need to increase the numbers. I'd suggest making only 1 or 2% increment changes at a time as even 1% is a significant difference in fuel.

You shouldn't play with the numbers on the left hand side of the table as there are a couple other tables that use these axis values. Take note that there's a lot of resolution below 300hz. This is because that's about all the airflow your engine sees 95% of the time while you're driving.

Repeat this process till your trims are within spec. Should point out any vac leaks you neglected to fix will be tuned for at this point. If you do go back and fix them at a later time, suddenly your trims might go a bit rich.

Once you get your fuel trims within spec, you can finally start tuning open loop. You need a long stretch of road (1-2 miles) where you feel safe and comfortable topping 3rd gear. A private stretch off public streets where the speed limit laws don't apply are ideal. You need to log foot to the floor from 2500rpms all the way till red line. The knock CEL feature of V2 will alert you when you're in danger of hurting the motor. Pay close attention to what's in front of you and not the logger. You can pull over and review the log after the pull.

Tuning Timing tables

This is the first thing you should tune. Timing advance refers to the degrees that the spark plug is fired prior to the piston reaching Top Dead Center (BTDC). The higher the timing number in the load cell that the car hits during WOT operation, the further ahead of TDC that the spark plug is fired. This is known as advanced timing. The lower the timing number in the load cell during WOT, the closer to TDC that the spark plug is fired. As the rpm increases so does the timing advance. Why? Well the engine has faster speeds and the spark plug must be fired earlier or else there would not be enough time to complete the burn of the air/fuel mixture.

You'll note this behavior in the timing maps:

http://i.imgur.com/ChrGi.jpg

If you saw no knock in your logs, it's safe to say you can probably get away with adding a bit more timing. If you did see knock counts greater than 4 or 5 count, it's best to retard the timing numbers (read fire the spark closer to TDC) in the high octane ignition map(s) especially in the higher rpms.

Chrome has one high octane ignition map and one low octane map. I've never done anything with the low map but let me quick explain what it's there for. The code has a value it uses called Octane which is a percentage that varries from 0 to 100%. At 100%, it uses the High Octane map. At 0% it uses the low. Any variation in-between and it interpolates the values between the two tables.

The knock sensor adds or takes away from this Octane number based on knock count and how long the engine knocks.

More info on the Octane feature of the ECU here:
http://www.3sgto.org/f104/disassembl...code-7996.html


My approach to tuning timing is to follow the MTBT method, i.e., Minimum Timing for Best Torque. Simply stated, the method declares that a tuner should advance timing until advancing the timing no longer yields gain in power/torque or, lacking a dyno, until knock is encountered.

The method outlined above to setting the timing ONLY applies to 91-93 octane gasoline. If you are using E85 advancing the timing until knock is encountered will yield poor or catastrophic results. You can go past MBT on E85 and not encounter knock. You will end up damaging your engine.


Knowing what values to edit in the table simply comes from logging Load and RPM. Take this log for example:

http://i.imgur.com/0VGQe.jpg

High lighted are the areas where we saw knock. In the red circles you'll see RPM and Load. If you go to your timing table, all you have to do is look up the Load column and RPM row and see where they meet.

http://i.imgur.com/jPajn.jpg

Since we saw so much knock in this area, it's probably wise to lower the timing a couple degrees in order to deter it.

Note: You'll notice that the timing numbers don't necessarily match the numbers in this table. This is because there are several correction factors for timing which I won't get into too much detail here. One of the corrections is the knock sensor itself. For every knock count takes about .32 degrees of timing away from advancement. What you're seeing in the log is the final spark advance the ECU is calling for. Since there was so much knock, timing was reduced a few degrees, hence the discrepancy in the log vs the table.

Upping the Airflow

For years you've been told that more power comes from more boost. Now I need to get you away from the idea. Like the days of the EGT gauge when widebands starting becoming affordable, the boost gauge is fairly pointless now when you know the engine's true airflow. Airflow is horse power! The object of the game is to get as much airflow (Load) thru the motor as possible! You'd think that more boost would = more airflow and most of the time it does. ...but manifold pressure never gives you an accurate idea of airflow because there are all kinds of conditions which influence pressure. This is why most Speed Density setups have difficulty getting tuned accurately. 15psi from 9Bs is only a fraction of the airflow compared to 15psi from say, DR750s. The stock ECU doesn't know, nor does it care at all what PSI it's generating. Everything is done off the airflow readings from the MAF. See with a piggy back, you always had to fool the ECU into seeing less air in order to compensate for your larger injectors. We don't need to do that anymore. :)

This is the biggest issue with ALL boost controllers out there. They target a specific PSI and have no regard to airflow. Ever notice your car seems to have "good days" and "bad days"? The tune drifts doesn't it? This is because 15psi when it's 30 degrees outside is not the same amount of air when seeing 15psi at 80 degrees. Same thing with altitude.

There's nothing wrong with the traditional MBC or EBC. They've worked great for many many years and there's absolutely no reason you can't run them with your flash ECU. Just keep a close eye on your 2 byte Load numbers and be aware that depending on the weather, the ECU is going to see more or less Load (airflow) depending on what the outside air conditions are.

The stock ECU's airflow controller (more commonly called the boost controller) doesn't regulate boost at all. It regulates the wastegates based on airflow. This means it'll raise and lower the boost to compensate for all air conditions giving you the same airflow all the time which in turn means you get about the same HP no matter what! More details on tuning with the stock EBC here:

http://www.3sgto.org/f2/so-who-wants...tml#post138054


Tuning the Air Fuel Ratio (AFR)

After you get your airflow (boost) set to where you want it and your timing numbers don't give you any dangerous amounts of knock, the last thing to tune is your AFRs.

AFR refers to how many parts of air are mixed with how many parts of fuel. So an 11:1 AFR means that 11 parts of air are being mixed with 1 part of fuel to create the air/fuel mixture. When your motor is at idle or at cruising speeds your AFR is around 14.5-14.7:1. This is known as stoichometric or stoich for short. It has been found that the 14.7:1 mixture produces the least amount of emissions. And since cars spend 90% of their time at idle/cruise then that is the number that the manufacturers use to reduce the emissions on their car. It is worth noting that the 14.7:1 AFR does not produce the best gas mileage. The best gas mileage is produced are 15.2:1 AFR.

What AFR produces the best power for gasoline? Gasoline gives the best power when it burns at an AFR of 12.5:1. This is regardless of whether the car is normally aspirated, turbocharged, or supercharged. Some modern turbocharged engines with direct fuel injection can run that lean during WOT operation. The turbocharged Ecotec in the Solstice GXP is such an engine. That engine can boost up to 18 psi, yet it runs at 14:1 AFR at 3500 rpm and tapers down the AFR to 12.5:1 by redline.

So can you run your engine at 12.5:1 AFR? NO you cannot and should not. The 6G72 engine is over 20 years old, it does not have direct fuel injection, and the combustion chamber is not designed to handle such a lean AFR. Furthermore, if the car is running on 91 octane gas. Under high boost and lean conditions, 91 octane gasoline becomes very unstable and can self ignite causing knock and other assorted problems.

So why tune the AFR last? There are two main reasons. First, changing your ignition timing will also impact your AFR. Second, increasing the boost will also impact your AFR. Why? The higher the boost the higher the load cell that the car will hit in the fuel map. Mitsubishi designed the fuel map to become richer the higher the load cells. So when you up the boost you will hit those higher load cells and the car will run richer. If you tuned your AFR before your boost, then you will have to do it again after you increase the boost. Why do things twice?

Moving onto the fuel table.

http://i.imgur.com/A86ml.jpg

Note that the numbers decrease as the load cell increase. In other words the car becomes richer as it sees more airflow. It is very important to note that the numbers in the load cells of the fuel map are NOT actual AFR numbers that you will log with a WBO2. When you get your VE table (MAF Smoothing) table tuned perfectly, you'll find that the wide band numbers will be very close to this table BUT under no condition should you enter the AFR that you logged with your wideband into the fuel map. They are just numbers. The higher the number, the leaner the AFR, and the lower the number the richer the AFR.

Setting your AFR depends to a large extent on the boost and timing that your car is running. When running the boost and timing mentioned in this essay, I generally set the AFR at 12.5-12 during spool up, 11.7-11.5 during peak boost and then slowly taper the AFR until it hits 11-10.9:1 by redline/cutoff.

So how do you go about editing the fuel map? Well, first you have to look up your wideband AFR readings from your logs and compare them to load and RPM in the same manner used for the timing map.

The formula for adjusting the fuel map is very simple. Look at the rpm row and load cell. This is the fuel map AFR (MAFR) and the actual AFR (AAFR) is the value from your log. Let us assume that we want a desired AFR (DAFR) of 11.4:1 in that load cell. What should the new map AFR (NMAFR) be?

NMAFR = DAFR * MAFR / AAFR

The NMAFR you calculated with this formula is the new number you enter in the fuel table. To make this easy on yourself, simply create a template in excel with the above formula and use it over and over again. This way you will not have to do any manual calculation. Just plug in the numbers and excel will take care of it. That is what I did and it works like a charm. This method takes the guessing out of AFR tuning and allows you create a very flat and consistent AFR.

Maybe one day I'll write a fuel map tuning program that takes your data log and automatically calculates a new fuel table for you to use.

Proper way to tune idle

I've walked you guys thru all the idle tables in this post (http://www.3sgto.org/tuning-engine-e...tml#post211650) but it seems a lot of guys don't understand setting the idle. Those of you who experience RPM dips, on/off throttle stumbles, etc... know what I'm talking about. Though you can sometimes get away with setting the target idle RPMs, flashing then turning the key, there's an initial setup you have to go thru in order to ensure your car will idle properly.

This setup is actually taken out of the Mitsubishi manual for our cars. The process is exactly the same as any other Mitsubishi. This post applies to turbo and NA cars as well!


This is the procedure:

*Install NEW/Remanned throttle body
*Verify TPS is set properly and Idle Switch works
*Flash ECU with your target idle tables set to whatever desired idle RPMs you wish
*Drive the car until engine is completely warmed up
*With the engine still running, put the ECU into SAS mode (make sure your AC is OFF)
*Adjust BISS/SAS till engine idles at the RPM you want
*Disengage SAS mode



First off....

***Replace your throttle body!!!!

All our cars are approaching the 15+ year old mark. The throttle body is the crucial part of the engine which regulates idle and cruise operations. 90% of all issues come from sensor failures, clogged FIAV and leaking BISS and throttle plate screws. To compound the issue, nearly every car gets this oil muck saturated within the small chambers within the throttle body which impact airflow. I'd highly highly HIGHLY recommend you get it replaced with a NEW unit from mitsu, or contact April to get it rebuild. She does great work rebuilding our throttle bodies!!

http://www.3sgto.org/tuning-engine-e...ice-10630.html

If you can afford $1500 for turbos, then you can afford to get your throttle boy rebuilt. Don't be cheap. ;)




Next....

After your new throttle body is installed, it's crucial that you don't have the throttle cable too tight. You can verify this by logging TPS with EVOScan. You should see values somewhere between 10% and 13% with your foot off the gas.

You also need to verify the idle switch is working with EVOScan (it's just a simple on/off). You see a value of 1 with your foot off the gas pedal, and a value of 0 with it slightly depressed.


Note: Some people are reporting that EVOScan isn't logging the idle switch correctly.

Verify this is what you're seeing in EVOScan:

http://i.imgur.com/CxC9qhi.jpg

If not, you'll need to edit that log value to match the screen shot (right click, edit data item....)




Next...

After you get your injectors scaled, your intake/fuel and timing maps tuned well enough to at least let the car start, run and drive, there's still a calibration that needs to be done with the BISS (also called the Speed Adjusting Screw) in the throttle body. This is what I'm talking about:

http://i.imgur.com/44gL6g7.jpg

Note: In this image the cover for the BISS is removed (usually it's missing on many cars).


SAS mode

If you recall in the chrome manual I talked about the idle timing stability control. The ISC will get the airflow in the right range for your desired idle RPM but it's ignition timing which is used to keep the idle at the desired speed. You've probably noticed that at idle, your timing values are always inconsistent and constantly jumping around. This is why.

When calibrating the BISS, the ECU has an input switch to disable this function along with the ISC all together so you can properly set your idle without the ECU trying to counter your adjustments. This is called SAS mode. There are 2 ways you can put the ECU into SAS mode. The first method is shown in the WIKI linked above. The second method (the easy way) is to use EVOScan.

Open up ECUFlash and the .bin file you flash to your ECU. Scroll down to the bottom and click on the Diagnostics tree, then Select MUT Actuator Mask:

http://i.imgur.com/YCWXcIK.jpg

These are a list of all the MUT commands I've found in the ECU. What these commands do is they manually activate switches on the ECU to test a function. In this case we are going to use MUT command C3 to put the ECU into SAS mode.


So start off by driving your car till the motor is completely warmed up, then pull over and let the motor idle. Open EVOScan and scroll down to the bottom.

Ever see this?

http://i.imgur.com/Xb9EpZK.jpg

If you enter in the MUT command into the Custom Request box, then check the repeat box, you will activate the switch. :) Very handy feature for testing solenoids/relays/fans to make sure they are working properly!

So you have your engine warmed up and idling what you need to do now is data log RPM. You can NOT use the stock Tach to set your idle. It's not accurate enough to tell you the exact engine RPM. Start your datalog and monitor your engine RPMs appearing on the screen.

In this case, we just want to put the ECU into SAS mode so you just type C3 into the Custom Request box then check repeat.

http://i.imgur.com/Ut3Ja87.jpg

As soon as you hit enter (with the logger still connected), you'll see some numbers appear in the Response box telling you SAS mode has engaged. You'll also notice your engine idle will change.

Now is when you pop your hood and adjust the BISS/SAS. A simple flat head screw driver will work just fine. Turning the screw clockwise will lower your idle and counter clockwise will raise it. You'll notice very suttle turns will make a HUGE difference in RPMs. Just a 1/16th of a turn can make as much as 100 RPM difference.

Stock these cars are setup for 650-700rpms at idle BUT you can make this any value you'd like. I typically go for 8 or 900rpms for better oil pressure and smoother idle with cams. Just remember to match the target idle RPM tables to whatever RPM you're trying to manually set it to in SAS mode!

http://i.imgur.com/1fhNYut.jpg

Once again, disregard the stock tach while you're setting the idle! Look at the RPM number you see in EVOScan!

After your idle is set, uncheck the Repeat box and delete C3 from the Custom Request box and the ECU will return out of SAS mode.

You will be absolutely amazed how much smoother your car will run now. :)

Discussion here:
http://www.3sgto.org/tuning-engine-e...roper-way.html

***more to come soon along with several updates! :)

How to tune your fuel trims

This is one of those things that needs to be done individually on each car. It's actually quite simple. It's harder to explain than actually tuning it. All you're doing is changing the way your MAF reads air

So the first step is to tune your car so that the O2 sensors are cycling in closed loop. It's not that closed loop targets any specific AFR, all the ECU is trying to do is get the sensors to cycle between .1 and .9 volts. Unless there is something really screwy with your setup, there isn't any reason why the ECU won't operate in closed loop right out of the box with your injectors scaled.

Let's start with the Intake tables. We got the MAF scaling table. Every type of sensor out there has a scaling. Doesn't matter if it's a temperature, pressure, frequency... The MAF scaling is quite simply just a table that relates the frequency of the MAF to an amount of air. The higher the frequency (HZ), the more air is being sucked into the motor by the turbos. When you swap in an EVO MAF, you change the MAF scaling table to match the readings the EVO MAF reports.

http://i.imgur.com/laCsg.jpg

The blue numbers correlate to a frequency the MAF is sending to the ECU, the right side is the airflow that frequency corresponds to.

The MAF Smoothing table is a correction factor applied to the MAF scaling table lookup.

http://i.imgur.com/qbrf24m.jpg

Mitsubishi put this table into the code to adjust for the changes having the sensor installed in the car compared to what it reports on a flow bench. The NA's and TT cars have the same airflow sensor (in the 98/99 cars anyway) BUT the MAF Smoothing table is quite a bit different!

http://i.imgur.com/8l7cJ.jpg




What does this have to do with fuel trims?

After the ECU knows the amount of air being ingested into the motor, it then can calculate an IPW and spray in the proper amount of fuel. Except there are several "X factors" that vary from car to car. Intake leaks, fuel pressure, compression variances, VE, injector flow, spark strength, cylinder temperature... All the math done in the code to calculate that picture perfect AFR and it's almost always never what's expected due to all these X factors. That's why we have sensors in the exhaust. They measure the AFR and a correction is applied to adjust it back to where we want it.

The long term fuel trims are a way for the ECU to remember how much correction is needed to keep that perfect AFR again. Problem is, it only has so much range. About +/-12.5% in the ROM. It's important to tune your trims to be +/-5% to keep at least some adjustability in the code so it can do it's job of keeping your motor running in closed loop.

Remember each trim is updated once every 4 minutes and it takes 16 minutes for the trim to have gone completely thru the cycle. So you're gonna want to drive your car for a while to get the trims settled.


Starting with logging just the Low and Mid Long Term Trims (front and rear). You don't need to see any other information.

Say, for example, your Low trim Front is -10.6% and your Low trim rear is -2.8%. We want to get that front trim back above -5% but not going so far that it brings the rear trim out of spec either. What this means is we want to add at least 6% more of fuel to bring that trim within spec. Tuning Chrome to bring those trims back within that 5% range is actually quite easy. Especially if you're familiar with this table:

http://i.imgur.com/BTsBcDw.jpg

The first row in the table shows us that anything under 101 HZ the ECU uses the Low fuel trim and from 101 to 503 HZ the ECU uses the mid trim.

http://i.imgur.com/GM3G828.jpg

What this means is we need to add another 6% to the MAF Smoothing cells in the low fuel trim range.

http://i.imgur.com/grY6Vas.jpg

Flash these changes to your ECU and drive around with them for a while. Your long term LOW trims should gradually increase the 6% needed to come back within spec. :) You may have to go back and forth with it a few times before it's all perfect but the general idea behind tuning is simple.


It's just like an SAFC only instead of adding or taking away fuel based on RPM, you're going right off the MAF signals itself. If you're feeling crafty, you can even disable closed loop entirely and tune strictly off your wideband and this table alone. Log your wideband and 2 byte airflow and add or take away fuel from this table in the HZ range till you get your desired AFR. The next version of chrome will have this table extended AND allow for finer correction values (.1% instead of 1%) so you can really get particular with fine tuning your car. Use the fuel table itself as a target AFR table.

The EVO guys always played with their injector scalings and latencies to bring their trims within spec. Never really understood that approach. It's the air count compensation that's off, so that's what should be fine tuned.



Note that the last row is only 1600hz. This doesn't mean that the ECU can only read up to 1600hz. It can go as high as the MAF can count. All it means is that anything above 1600hz uses the last row in the table. You might want to consider rescaling the blue numbers to read higher if you wish to fine tune in a higher airflow range. Even a 100% stock car sees over 1600hz BTW so definitely be considering it. :)


Discussion here:
http://www.3sgto.org/tuning-engine-e...ms-chrome.html

Start to finish, the whole process is very time and gas consuming and it can get very frustrating but with time and patience, it can be done! Don’t be afraid to ask questions but please don't PM me. Start your own thread or post in the linked threads from the Tech Manual! If you are polite and have done your reading prior to asking your question, then I will be a lot more inclined to help you.