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#2: 08-25-2012, 11:04 PM
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Title: Authorized Tuning Vendor
Location: Colorado - Cryotune Performance
Car: 08 Spec B now,06specB,2011 STi,2015 WRX
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Tuning FAQ

I wanted to make a FAQ related to pre-tune/post tune questions to help everyone out and obviously reduce the amount of emails needed to be answered which would allow me more time to work on what is important, YOUR TUNES! My theory is by taking the time to write this I will allow you to be more prepared when it comes to making the most out of your e-tune. I will try and update this as needed since it is always the same questions that are being asked.

Always plan your setup and determine your goals before purchasing parts *ie how much power do I want to make? How fast do I want to go? What will I be doing with the car drag, autocross, mountain carving daily driver, driving to the moon….Just making sure you were paying attention because this is the most often overlooked aspect when people begin throwing money at a car. They end up buying parts twice or more until they are happy with the overall performance and response, always remember power is not everything.

A Stage 1 tune will normally clean up some of the drivability issues in all model years as well as pick up smoother and quicker acceleration. The torque increase is more noticable than the overall hp increase but generally makes the car funner and more responsive. Some say a stage 1 tune makes the car run as it should of from the factory but nothing crazy. This will be the #1 hp to $ modification.

A Stage 2 tune moves forward and actually creates a decent amount more torque than stock and wakes up the car on the top end in the higher rpms as well. Most people are very impressed at the difference a stage 2 tune can make when compiled with the right modifications. A lot of people feel stage 2 power is all they will need in their modification quest for a strong daily driver.

Intakes –

1. A new panel filter normally will not require a tune as the ecu has enough adjustment to play with to compensate. Keep in mind any oiled filter like the K&N may cause issues by getting oil on the mass air flow sensor itself and require cleaning every once in a while after a recharge.
2. An Intake kit WILL require a tune designed for it regardless of Brand for the LGT/OBXT
3. Removing the Snorkel in the fender well will not increase performance and it should be left alone if using the stock intake box

Top Mounted and Front Mounted Intercoolers

1. A change to a larger TMIC from stock or from aftermarket to more efficient may or may not require a tune based on logs. A change from a stock TMIC to a FMIC may or may not require a tune based on logs. The one thing that can be said is to get the most out of the modifications you invest in it must be tuned for and every car will respond different. A Front mounted intercooler will not necessarily perform better for all situations and should be researched to see if it’s a benefit for your particular setup.

2. Most times a FMIC with a proper tune will result in a very small difference in turbo spool up but will be felt more in between shifts as the turbo has to build pressure in more piping. It happens very quickly but there is a delay over the same TMIC setup.


1. There is really no difference between power output of downpipes regardless of brand or style *ie divorced, open bellmouth, Vishnu tubular wg style etc* They all perform the same operation.
2. Gutted stock downpipes work but do not address the issue with a wall right in front of the wg flapper and the difference can seen when comparing the stock piece to an aftermarket unit.
3. Catted and Un-catted downpipes do not really produce much of a difference in power output and for most comes down to cost and local emissions laws
4. The factory catback exhaust is not considered a restriction until around 300+hp but an aftermarket unit does allow for more flow which is generally considered better plus many like the added sound benefit.
5. 2005-2006 LGT/OBXT models DID come with the catted up pipe,2007+ did not.

Injectors –

1. Plan your injector size based on your ultimate goals, If your upgrading injectors your probably upgrading the turbo, will you want E85 in the future or are you someone who normally upgrades to the next step often? Normally anything lower than 1000cc is pretty easy to control when tuning but if you have no plans of going bigger than a 16g on gas then 740’s are probably a better option, don’t go bigger than you need to. Don’t try and re invent the wheel and research what others with the same setup you are planning are running.

Blow off valves/by pass valves –

The Factory by pass valve is very capable of stage 1 and stage 2 levels and rarely presents any mechanical failures. After 18psi some have showed signs of leaking where as others have held 22-23psi daily for years with no signs of failure. Most wait untill they fail to replace them and is good practice in my opinion. There are a few aftermarket units that perform like stock and are of much better design so those can be great replacements if your stock unit does fail. Normally “tuning” the bpv/bov consists of adjustment of different springs for pressure.

Boost Controllers –

The most common question is if a manual boost controller will work on these cars. With the exception of a hybrid type system including the stock or aftermarket Electronic boost control this is not a recommended method because it disables all of the factory control for changes *temp,atm,etc.* The most common boost controller used on the Legacy gt’s is a 3 port electronic boost controller that can be used by the ecu to control boost. There are a few great options on the market but some are cheaper at the expense of not plugging into the factory harness. I can personally say using the stock boost control system up to stage 2 is more than adequate. If the turbo is upgraded I recommend upgrading to a 3 port EBCS to achieve and hold higher boost thresholds as well as have more control but will not overcome the short falls of a turbo falling off in power *ie vf40/46 in higher rpms*.


Software Needed for Tuning/Logging your subaru
Here are some helpful links to the software needed for the E-tune process
All software is linked to the website of origin out of the respect for the creators and operators. Please do not host any of these programs on your own site but link it to the people that deserve the credit. - A Free opensource program used to view and modify the factory subaru ecu. Many tables can be modified including timing,afr,boost response,delays,limiters etc all while keeping all the factory failsafes and drivability. This program also has the logger mentioned and can be used to monitor MANY perameters in the ECU like Maf voltage,knocksum,KFBC,STFT,LTFT,RPM,TPS,Turbo dynamics etc. This program was made by guys in their spare time as enthusiests and deserve all the credit in the world. *you must download current definitions for the logger and romraider before you can view any roms*

The definitions for Romraider, The logger and ECUflash are all different and all must be installed. The instructions on where to put these downloads are included in the links as well.

Logger Def’s -
ECU Flash – Def’s -

Learning view - This program was also written by the opensource guru's and is an amazing tool to pull a snapshot from your ecu to see how everything is performing. This program will show you a screen shot with your current Ignition Advance Multiplier,Long term fuel trims,knock learning being perfomed by the ecu in a grid format and any pending CEL's. This action takes about 20-30 seconds and gives you the option of resetting the ecu as well. - This is the place you will have to purchase the "cable" to read/write/flash or log your subaru. The openport2.0 is the only option for 2007+ subarus but 2006 and prior have the option of buying the tactrix cable 1.3 for less money or some have luck with a vag-com cable available cheap off ebay. The vag com can be frustrating to get working but once its working its good most times. The 1.3 cable will have to be purchased used as tactrix no longer sells it.

ECUflash *download free from* - This program is used to "pull/flash" your ecu "rom" and save it to your laptop. MAKE SURE AND SAVE YOUR STOCK ROM IN A SAFE PLACE AND MAKE A COPY OF IT IN A DIFFERENT FILE. USE THE COPY TO VIEW/MAKE CHANGES TO. NEVER MODIFY YOUR ORIGINAL COPY OF YOUR STOCK ROM. Ecuflash has a built in rom editor but most people use ecu flash to pull the rom then they use romraider to view and edit the rom because of a few added features and romraiders specific design to subaru.

Cobb AccessTunerRace software - Cobb released the street tuner software a while back and then re-released the Accesstuner Race software after that. The accesstunerrace software is a FREE download for anyone who legally purchased a Cobb Accessport V2 and just has to be requested from cobb. The handheld accessport can log and show many perameters now but has to be downloaded to a pc to view the logs. The handheld unit also cannot make any major tuning changes *although it can make small idle and timing adjustments* The accesstunerrace software can be used to fully tune the ecu in the same way the opensource software can but just lays it out in a little different format. The ATR software also allows you to log,veiw live custom defined gauges, and has a map tracer that shows you what cell of what grid you are currently in at any given time on any given map.

Both romraider/ecuflash and the ATR software can be used to tune a vehicle to the same performance potential. The one major difference between opensource and the ATR software is the realtime tuning/tracing and being able to store multiple maps whether off the shelf maps or custom tuned maps on the handheld accessport. The realtime tuning can cut out much of the time needed for tuning certain tables during a road tune and allows the operator the ease of not resetting the ecu each time he wants to make changes to afr/timing/boost to see the outcome as well as not resetting all the ecu's learned parameters.

Both Romraider and ATR allow you to tune your vehicle to run great or horrible. If you dont know what your doing you WILL do more damage than good and it takes a lot of research and testing/logging to make accurate decisions on what changes need to be made.....log,log,research,log,log,research

A Learning view will need to be sent to me before a base map will be sent out if using Opensource. Please make sure you are familer with this process.

Air / Fuel Ratio's and you

Here are some helpful details related to AFR, Lambda, Wideband 02 sensors, Narrowband 02 sensors and such. Please provide opinions,experiences etc.

Air Fuel Ratio is a very commonly misunderstood concept and I didnt see anything like this posted so figured I would see if its helpful.

As simple as it sounds it is the amount of air to fuel ratio you are seeing inside/come out of the engine at any given point of time. This is measured from the factory 02 sensors all the time and the signal is then sent back to the ecu for processing. The 02 sensors are what are used to send the ecu signals to determine short term and long term fuel trims. The computer trys its best to stay at a preset AFR *air fuel ratio* to conserve gasoline during cruise and idle situations *light load*. This targeted afr is 14.7 for gasoline although with the 10% ethanol content in current gasolines the "total burn effect" occurs at a slightly richer mixture according to what some believe. This cruise and idle situation is called closed loop and is a process used to keep the vehicle constantly in the most effective range for emissions. The factory 02 sensors are called "wideband" sensors because of thier output capability but unfortunatly in terms of reading output at full throttle they are actually quite useless for a few reasons including the pressures created in the manifolds. They are designed to be very accurate within about 1.5AFR around idle and cruise situations *ie 13.5-16 afr*. Most Subaru 02 sensor readings from the computer peg at 11.XX since thats as rich as it will read regardless or true afr. It should be noted that the fuel mixture can actually be leaner than 11.XX and the factory sensor may still read 11.XX because of its lack of ability to produce true afr numbers that far away from stoich. *example: Factory sensor reads 11.14 when true wideband reading may read 11.3-11.6.*

It should also be noted that subaru targets richer idleing mixtures for different situations so its not uncommon to see swings from 14.2-14.7.

Well enough about closed loop fueling lets talk about open loop and wide open throttle afr. Openloop is a term used for when the computer stops making adjustments based on the stock 02 sensor readings and starts referering only to the primary openloop fueling table *+compensations*. Openloop basically occurs when your putting your foot in it in simple terms, the thing to note is there is a "delay" in the changeover between closed and open loop and can cause fueling issues for a modified car without changes in the tune to accomidate things like quicker spoolup and earlier peak boost/torque.

AFR is a term used as a ratio but changes depending on fuel being used. Because of this most tuners use a term called Lambda instead. Lambda is when all of the "fuel" in the cylinder has been burned and used as energy or for cooling causing a complete burn and nothing left in the cylinder. The biggest benifit with using lambda instead of afr is different fuels burn at different rates and will need different afr targets to acheive that perfect burn while lambda remains the same targets regardless of fuel. Although lambda is what I reference more I will base my details and explanations on AFR in this write up. Lambda is an easy conversion once you understand afr.

First off there is NO perfect afr or lambda to set and forget for any car, each car will want a little different afr but for the most part you dont have to reinvent the wheel. This is where doing a lot of research about your vehicle and what others have done come into play. Nothing will replace a dyno when truly calibrating afr or timing but knowing your "safe zone" can be extreamly helpful until your trying to wring out every last hp. AFR really doesnt change hp levels all that much when dialed in closley and comes down to safety more than anything else. The rule of thumb is to always start off rich because its a lot harder to hurt things quickly with an overly rich mixture although its very possible. Fuel is used to make power but at the same time is just as important in cooling the cylinder temps and keeping pre ignition and knock at bay. Thats the tricky part to finding an optimum AFR, rich best torque is key but many cars like a much richer mixture and would have a serious issue running that lean under all situations. Most subaru maps are set from the factory at a 12ish afr at the onset of boost tapering down to 10.3-10.5 which is safe but on the rich side during peak torque and high rpm on thier turbo motors. There are different theory's to making power with afr and as a personal opinion I feel power should never be made with lean mixtures but overly rich mixtures can be just as much of a power robber and must be leaned out to provide smooth power delivery. A overly rich mixture can feel sluggish and non responsive while a lean mixture can feel great but can easliy cause more damage. Contrary to the old saying "lean is mean" power actually starts to fall off on either side of rich best torque and lean best torque. Its a happy medium.

On to the Tools and Equiptment

Wideband 02 sensors used to be extremly expensive and were not an option for anyone other than high end shops and tuners. Now there are quite a few options that offer different formats to work with. The biggest thing to keep in mind is you have to be able to trust your equiptment so if you decide to buy used or cheap it may come back to bite you. Many times I have seen people try and save money on widebands and cost them motors or tons of time chasing thier tails tuning because of improperly working equiptment. Look at the features and benifits of each Wideband 02 kit and choose which ever suits your needs best. I chose the Zeitronix Datalogging software and am very happy with it. Most units work with romraider and Accesstuner Race now days. Something to note is the further away from the engine the Wideband 02 sensor is mounted the more of a "delay" you have to account for in your data. Some standalones will allow you to configure that but always something to keep in mind. If mounted behind a catylitic converter expect to see leaner values as well.

LC1 Wideband 02 sensor- One of the most common options for people right now, Bosch sensor, logworks software and cheap guage options as well.

Zeitronix wideband datalogger - Somewhat expensive but nice software,lots of options for display guages, Same bosch sensor

AEM wideband - works with guage but not actually sure if it has software availible. Never seen it advertised and only seen it used with AEMpro

PLX devices - works with guages, series of sensors or standalones. decent reviews as well. Make sure to purchase the usb adapter if you plan on logging to a laptop

These are a few of the name brand options but do research to see which will work best for what you are looking for. AFR should ALWAYS start at lambda *14.7 or 1.0* and steadily drop to your target afr in the primary openloop fueling table as long as the CL - OL settings have been tripped. Any bumps,divits or deviation from the target show changes might need to be applied to the scaling.

any questions,comments or opinions are more than welcome. Just figured I would try and post a little helpful information.

This will keep getting updated but this is a start.

Thanks and hope this helps out



Last edited by cryo; 05-06-2014 at 05:25 PM..
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