2nd Gen Engine FAQ - Turbos - MPG - Engine Builds - Engine Swaps - Engine Management
Under Construction with a new revised version
I've seen and answered countless questions about turbo charging the second generation Subaru Legacy. I'm putting together this FAQ to help clear up some of these questions.
If I have missed anything, please feel free to suggest something for me to add to this FAQ. I will edit it as I see fit.
Wiring Harness Merge - HOW TO
Can I turbo charge my Legacy?
Short answer is no, you can not. However, keep reading and I will explain ways that you are able to have boost in your car.Why can't I turbo charge my car?
I can go on for days explaining this. However I'll try to keep it short and to the point. The EJ25D is an open deck engine. It is NOT a strong engine and does not handle boost well. There have been people who have been able to run about 4 - 5psi on them though. This is typical for a TD04 turbo, and to be honest isn't enough power for the money you will spend doing it. You also run into other problems like weak internals and compression ratio. The EJ22E is a little bit of a stronger engine and can handle about 10psi, however the money thing comes into play here as well. You can do a swap for just a little more then it will cost you to boost your EJ22E and have considerably more power.What about the JDM second generation Legacys? They are twin turbo!
Unlike our USDM Legacys, the JDM Subaru Legacy has an engine designed to withstand the extra power of the turbos. The EJ20R has forged internals, and VERY good heads...I've seen Legacys online that have a turbo. How did they do it?
Most people do some kind of WRX or STI swap. This includes just about all of the WRX / STI guts. Engine, transmission, rear diff, ecu, wiring, subframe, etc. I'll go into more details later on.What other options do I have besides a WRX or STI swap?
There are a few other options out there. Most of the JDM drivetrains can be bought on Ebay for a reasonable price. Personally, I'm running an EJ20R setup with a stand alone ECU. You can also use the older USDM Turbo Legacy engines.What about my transmission?
The 4EAT and the 5MT are not strong transmissions. They do excellent under stock horsepower, but when you start adding the power of forced induction to them...they don't last for very long. They may work for a little while, but they will have severe problems A LOT sooner then then should.So if my transmission isn't strong enough, what should I do?
The easiest thing to do is to find a wrecked donor car. Or you can find a transmission / rear diff combo online. I'm currently running a JDM STI v3 5 speed with a stage 1 clutch. Its good up until about 400awhp.What about my exhaust? I've installed a turbo engine and I can't make the exhaust fit around the subframe. It looks like I have to cut part of it out!
Our stock subframes were not designed to accomadate for the turbo exhaust. The work around for this is to either use an 04 STI or any 02-07 WRX subframe. DO NOT cut your stock subframe. It will not be as strong as it needs to be if you do this. You can also run any of the USDM turbo Legacy subframes.So can you just give me a quick list of the parts I need to do a turbo swap?
This depends on what route you go. If you do a WRX / STI swap, you will need the followingSo I did a JDM swap with a stand alone ECU, but my car doesn't run right. What do I do?
You need to get your car dyno tuned at this point. Every ECU has parameters and settings for the engine to run within. With any kind of stand alone ECU, you have to "tune" these settings to your specific setup. Its not hard to do, its just hard to get it right. If you screw up when you do it, it will cost you your engine. If you really did a swap and didn't know the answer to this, you should probably build model cars instead.I want to do a swap, but I'm concerned about my stock axles. Will they be able to handle the extra power of a turbo engine?
You should be fine within reason. You're not going to be able to put 500awhp to stock axles, but the 200awhp area is fine on stock Legacy axles. A decent upgrade is STI or WRX axles. They are able to handle a little more abuse then the Legacy parts.I want the EJ20R twin turbo JDM engine in my car! It will bolt right up....right?
Wrong. Its VERY difficult to run the twin turbo setup on our USDM Legacys. The reason for this is the difference between right and left hand drive. Our steering linkage, brake booster, etc gets in the way of the second turbo. I have seen a USDM Impreza run the twin turbo EJ20R, but they had to heavily modify it. My personal EJ20R has been converted to a single rotated turbo. I HIGHLY recommend the EJ20R because its an excellent engine, but expect to NOT have a twin turbo system with it.So whats the hardest part about doing a turbo swap?
The wiring in our cars is a nightmare. If you do a WRX / STI swap with the WRX / STI ECU, you have to "splice" the stock Legacy wiring harness, and the WRX harness together. If you run a stand alone ECU, you will have to make a custom wiring harness. Trust me, there are A LOT of wires.I chose to do a WRX / STI swap, but I want a little more power out of the stock WRX / STI drivetrain. What can I do?
Before you start upgrading the stock WRX / STI setup, you should look into some kind of piggyback system like a CobbAP. This way, you're able to tune your car to whatever mods you have installed and get all the power out of it. After a piggyback, you can do a rotated turbo setup with something bigger then the TD04 or VF39. Bigger injectors, exhaust, MSD, boost controller, etc are all good upgrades.I always look on my local Craigslist classifieds for a wrecked WRX / STI, but I never see one. Where can I find one at?
The best places to look are local Subaru forums, NASIOC, and car auctions.I want to use X block with X heads for my turbo build. Can I do this?
YES! This is whats known as a "hybrid" build. Usually, you can pair any EJ series head with any EJ series engine. I would recommend using ARP head studs if you plan on running a lot of boost.I'm going to install a WRX engine, but I want to use the STI 6 speed transmission. Is this possible?
Yes it is. Just like the heads, you can mix-match engines/transmissions. Transmission mounts may be different for each transmission however. The STI 6 speed has the DCCD that will need to be wired in though, and I'm not sure how to do it...but I do know that it has been done on our cars.Can I use my stock Legacy clutch?
Probably. I would suggest otherwise though. It will likely shatter on launch or slip under power.What about gas mileage after a turbo swap?
Your gas mileage will suffer some. I know our cars are not the most fuel efficient cars on the road already....but any time you add more power to a vehicle, it gets worse gas mileage. My Legacy turbo isn't THAT bad on gas. The worst part of is is that I have to run 93 octane.What else do you suggest?
I suggest some suspension and brake work to be done with your swap. If you're anything like I am, you take advantage of the AWD system and haul *ss through the corners. Now that you have more power under the hood, you're going to be able to come into these corners a lot faster. Better suspension and better brakes are a MUST. I have WRX brakes and D2 Racing coilovers. I'm pretty happy with the suspension, however I am wanting to upgrade the brakes even more so then they already are.What is your current turbo setup?
I have a 1995 Subaru Legacy L. It has the JDM EJ20R engine in it paired with the JDM STI v3 5 speed and a limited slip rear diff. I have a Megasquirt stand alone ecu, port/polished heads, 252 cams, upgraded fuel pump, MSD, 660 injectors, front mount intercooler, rotated TD04, full 3 inch turbo-back exhaust, etc. I'm happy with my current setup, but its only good up until about 400awhp.There isn't much space under my hood. Are you sure all this turbo stuff will fit?
Yes it will fitMechanically, you can bolt up any EJ series engine to any EJ series transmission, and drop the two into any car that was designed with any EJ series engine.
The following is a list of Subaru EJ Turbo Charged engines that are able to fit into the second generation Legacy / Outback / Impreza
2.0L Single Turbo
-EJ20G JDM 93-96 STI, WRX 92-962.0L Twin Turbo must be converted to single turbo
-EJ20H JDM 93-98 Legacy2.2L Single Turbo
-EJ22T USDM 90-94 Legacy2.5L Single Turbo
-EJ255 USDM 06-11 Impreza, 04-11 Forester, 03-11 Legacy, 04-06 Baja
If you're needing the FSM - look here http://www.sl-i.net/FORUM/viewtopic.php?f=14&t=20753
A good read about swaps http://www.modified.com/tech/0403scc...ine/index.html
This thread is intended to be a consolidated source of information about gas mileage in our cars.
If you have any questions pertaining to MPG, please post them in this thread.
Please keep one thing in mind. You do not drive a 3 cylinder Geo Metro. You're NEVER going to get 35+ MPG. On a well running Second Generation Legacy, you can expect up to mid 20s
Things to replace
Things to clean
NON-TURBO ENGINE SWAP FAQ
Here is a list of non-turbo engines that can be fitted to any BD, BG, or BK Legacy. If an older non-OBDII engine is used, some modifications must be made for OBDII sensors.
Used in Impreza GC1 seriesEJ16SpecificationsEJ151
information from http://en.wikipedia.org/wiki/Subaru_EJ_engine
ENGINE MANAGEMENT FAQ
I am NOT a professional with engine management. I know some about it, but there are gaps in what I do know. If someone finds something that I'm missing, please let me know and I'll add it in.
DISCLAIMER : It is a violation of federal law (and possibly State law depending what state you're in) to tamper with vehicle emissions equipment unless the vehicle is for use on private property and closed courses only. It is not legal to operate a vehicle on public roads if it has a modified emission system. - United States law. I don't know about other countries.
When do I need engine management?
I believe every car can benefit from engine management. Out of the factory, your car is "tuned" to run as efficiently and clean as possible (thank you EPA). Unfortunately, when you aim to make a car efficient...you sacrifice some power.So what are my options? Am I able to reflash my stock ECU?
You are not able to flash your stock ECU. There are two options that one can choose fromI have an automatic car, but I want engine management. Is this possible?
Yes it is, however your only option is a piggy back system. You will still need your stock ECU to control the transmission, and you won't be able to do that with a stand alone.So I got my engine management and installed it, but my car doesn't start or runs poorly
You need to get it "tuned". Read the tuning FAQ in the post below this one.
I have copied this from NASIOC. Its specific to the WRX / STI, however most people who do swaps in our cars will be using a WRX / STI swap. A lot of the information crosses over to other engines as well.
Any mention of "open source tuning" aka RomRaider or the likes does not apply unless you run a WRX or STI ECU. If you plan on running a stock Legacy ECU, open source tuning will NOT work.
HYBRID BUILDS / FRANKENMOTOR FAQ
What is a hybrid build / frankenmotor?
It is a term used for using the heads off of one Subaru engine and the bottom of another.Can you give an example?
A popular hybrid build is an EJ257 (STI 2.5L) bottom end (block/crank/pistons) and EJ20 (WRX) heads / intake.What is the advantage of a hybrid build?
One of the biggest advantages is compression. Some decide to do hybrid builds to get higher compression then stock.So what heads can I combine with what block?
Pretty much any head intended for any EJ engine can bolt up to any EJ block.So whats the catch?
Most EJ engines are interference engines....meaning when the valves open they drop down into the cylinders. This is why when a timing belt breaks, you have to rebuild the heads.All the hybrid builds I have seen are for turbo engines. Can I do this with a non-turbo engine?
Of course you can! The reason hybrid builds on N/A Subarus is not well documented is because most decide to do turbo builds.Can I use my USDM EJ25D heads on a JDM EJ20K block?
Yes. I don't know what kind of benefit it would give you though. Usually people like to pair heads off a smaller engine onto a bigger block.What transmission can I use with my hybrid build?
Just about anything. Any transmission that was meant to be paired with any EJ engine will bolt up just fine.Can I use my stock ECU?
It depends on how big of a change you make. There is no concrete answer to this question.Should I have some kind of after market engine management?
Of course! I actually suggest even those running stock to have some form of engine management. Stock ECUs suck.
What is "tuning" your car?
This is a term used for programming the settings in an aftermarket ECUDo you mean that my stand alone or piggy back isn't plug and play?
Yes, thats what I meanSo how does one tune their ECU?
If you don't know the answer to this already, you should probably go get your car professionally tuned. If you want some basic information on how to do it yourself, I will cover the basics later on in this FAQ.What are all these horror stories I've heard and youtube videos I've seen of cars blowing up on the dyno about?
Cars blow up on the dyno for several reasons. One reason is part failure.This is always a risk because when your car is on the dyno, it is being pushed to its limits. Another cause of "blow ups" is the tuner. When adjusting the air/fuel ratios, spark advance, duty cycle, etc....things can go drastically wrong.So what will getting my car tuned do for me?
Ill sum this up as quick and simple as I can.I picked out a tuner and he gave me a list of mods to do before I got my car tuned. Should I listen to him?Air/FuelYour air/fuel ratios are very important. When running lean (too much air), your engine has a tendancy to pre-detonate the fuel. Pre-detonation can cause serious internal engine damage. The most common damage to Subarus from detonation is cracked piston ringlands.Spark AdvanceThis is another way to combat detonation. If your fuel is ignited by spark before TDC, you're less likely to get uncontrolled detonation.Fuel EconomyWhen tuning a car, this isn't really a major concern since most who do aftermarket engine management are going for as much power as possible. With that being said, a tuned ECU will run MUCH more efficiently then one that is not tuned. It will make more power and use less fuel.
Absolutly. Remember, the guy who is tuning your car is likely MUCH more experienced then you are. He probably knows what he is talking about. With that being said, each tuner has their strong points and their downfalls. While one tuner may be a pro at tuning Megasquirt systems, the other tuner down the street might not even know where to begin with one. Its best to provide your tuner with a car that has modifications that he is familiar with. That way he can tune it better, and there is less of a chance of it blowing up on the dyno.Should I plan for disaster on the dyno?
Hope for the best, but plan for the worst. My first trip to a dyno resulted in a trigger wheel flying off of my crank pulley and destroying a bunch of stuff under the hood. A 3lbs metal wheel spinning at 6000rpms can cause a lot of damage when it brakes off. NEVER put your car on the dyno if you're not prepared to repair what might happen.How strong are the straps that they use to tie down my car?
Pretty strong.....They are defiantly strong enough to hold your "stationary" 90mph car in place on the dyno. The chances of your car jumping off the dyno are slim to none as long as the tuner keeps his foot off the brake pedal.Why was I told I need an extra o2 sensor bung?
This is pretty much standard. You need a free spot for an o2 sensor since this is what the dynos computer will measure your air/fuel ratios withStoich fuel mixture is 14.7to1...but my tuner told me that I want to get about 11.0to1. Why is that? Isn't that running a little rich?
Stoich fuel mixture doesn't really matter when you're running higher levels of boost. Running a little on the rich side does two things. The extra gasoline in the cylinders helps cool the cylinder walls, and it helps prevent detonation (since you detonate when the engine is lean)What is the standard hourly rate for tuning?
This varies. I pay $150 an hour for professional dyno tuning.How can I prepare my car to get tuned?
Make sure everything is in working order on your car before you get it tuned. This includes a fresh oil change, checking all your fluids, tires, etc. The reason is because if your car has to be shut off on the dyno and repaired, you're still paying $150 an hour for dyno time while the repairs are done. Do everything in your power to prevent this from happening.What about Cobb Accessport? It says I don't need a dyno tune!
True. Cobb AP (and others on the market) will send you a file to flash over to your ECU. These are generic tunes that are close, but not perfect. You will always get a MUCH better tune having a pro tune your car for you.So if I want to start street tuning my car myself, what do I need to connect to my ECU?
It depends on what ECU you are using. A laptop is a must. I like to use a power inverter so I can plug my laptop in to keep it from dying. On top of that, you need whatever cable / software that is specific to your ECU. This is usally either a USB cable or a Serial cable. Both kinds of cables cna be bought for pretty cheap. The software comes with your ECU, and some venders offer a download of the software on their websiteWhat do I need to learn about before trying to tune my own ECU?
You need to understand how an engine runs. Not just the basics, but the computer operations and how the computer tells the car to delive air/fuel/spark to the engine. This includes air/fuel ratios, duty cycles, spark advance, ignition timing, TPS calibration, fan controls, fuel pump controls, launch control, flat shifting, map, etc. There is A LOT to itSo if I start tuning my own ECU, what will the program look like that I'll be working with?
It depends on what ECU you are using. Here is a picture of the Megasquirt softwareCan I tune my car to run nitrous?
Yes you can. A stand alone ECU is a MUST if you want to do this.Someone told me that I can set up traction control by tuning my ECU. Is this true?
Yes it is. Even if your car doesn't have traction control stock.I got my car tuned, but I didn't end up with as much boost as I wanted. What can I do to get more boost?
Running E85 is probably the most popular thing done to acheave more boost. However, this requires its own tune.
DISCLAIMER : Tuning an ECU is a very dangerous thing to do. If you plug in one wrong setting, it can cost you your engine. If you decide to try and tune your ECU yourself, be VERY careful.
CHECK ENGINE LIGHT
courtesy of obd-codes.com
P0001-P0099 - Fuel and Air Metering and Auxiliary Emission Controls
DTC Codes - P0300-P0399 - Ignition System or Misfire
Manufacturer Specific Codes
P1086 - Tumble Generator Valve #2 (LH) Position Sensor Circuit Low Input
P1087 - Tumble Generator Valve #2 (LH) Position Sensor Circuit High Input
P1088 - Tumble Generator Valve #1 (RH) Position Sensor Circuit Low Input
P1089 - Tumble Generator Valve #1 (RH) Position Sensor Circuit High Input
P1090 - Tumble Generator Valve #1 (RH) Malfunction (Stuck Open)
P1091 - Tumble Generator Valve #1 (RH)Malfunction (Stuck Close)
P1092 - Tumble Generator Valve #2 (LH) Malfunction (Stuck Open)
P1093 - Tumble Generator Valve #2 (LH) Malfunction (Stuck Close)
P1094 - Tumble GeneratorValve Circuit #1 (Open Circuit)
P1095 - Tumble Generator Valve Circuit #1 (Over Current)
P1096 - Tumble Generator Valve Circuit #2 (Open Circuit)
P1097 - Tumble Generator Valve Circuit #2 (Over Current)
P1100 - Starter Switch Circuit Malfunction
P1101 - Neutral Position Switch Circuit High Input (A/T)
P1101 - Neutral Position Switch Circuit Malfunction (M/T)
P1102 - Pressure Sources Solenoid Valve Circuit Malfunction
P1103 - Pressure Sources Switching Solenoid Valve Circuit
P1104 - Engine Torque Control Signal Circuit Malfunction
P1106 - Engine Torque Control Signal 2 Circuit Malfunction
P1107 - AIR System Diagnosis Solenoid Circuit Fault
P1110 - Atmospheric Pressure Sensor Low Input
P1111 - Atmospheric Pressure Sensor High Input
P1112 - Atmospheric Pressure Sensor Range/Performance Problem
P1115 - Engine Torque Control Cut Signal Circuit High Input
P1116 - Engine Torque Control Cut Signal Circuit Low Input
P1120 - Starter Switch High Input
P1121 - Neutral Position Switch Circuit High Input (MT Vehicles)
P1121 - Neutral Position Switch Circuit Low Input (AT Vehicles)
P1122 - Pressure Sources Switching Valve Circuit High Input
P1124 - TCS Signal Circuit High Input
P1130 - Front Oxygen Sensor Circuit Malfunction (Open Circuit)
P1131 - Front Oxygen Sensor Circuit Malfunction (Short Circuit)
P1134 - Front Oxygen (A/F) Sensor Microcomputer Problem
P1137 - Front Oxygen (A/F) Sensor Circuit Range/Performance Problem
P1139 - Front Oxygen (A/F) Sensor #1 Heater Circuit Performance/Range Problem
P1141 - Mass Air Flow Sensor Circuit High Input
P1142 - Mass Air Flow Sensor Circuit Low Input
P1143 - Pressure Sensor Circuit Low Input
P1144 - Pressure Sensor Circuit High Input
P1146 - Pressure Sensor Circuit Range/Performance Problem (High Input)
P1150 - Front Oxygen Sensor Heater Circuit High Input
P1151 - Rear Oxygen Sensor Heater Circuit High Input
P1230 - Fuel Pump Control UnitMalfunction
P1244 - Wastegate Control Solenoid Valve Malfunction (Low Input)
P1245 - Wastegate Control Solenoid Valve Malfunction (Fail-Safe)
P1301 - Fire Due To Increased Exhaust Temperature
P1312 - Exhaust Temperature Sensor Malfunction
P1325 - Knock Sensor Circuit Low Input
P1400 - Fuel Tank Pressure Control Solenoid Low Input
P1401 - Fuel Tank Pressure Control System Performance
P1402 - Fuel Level Pressure Sensor Circuit Fault
P1420 - Fuel Tank Pressure Control Solenoid High Input
P1421 - Exhaust Gas Recirculation Circuit High Input
P1422 - EVAP Purge Control Valve Circuit High Input
P1423 - EVAP Vent Control High Input
P1440 - Fuel Tank Pressure Control System Low Input
P1441 - Fuel Tank Pressure Control System High Input
P1442 - Fuel Level Sensor Circuit Range/Performance
P1443 - EVAP Control System Vent Control Function Problem
P1480 - Cooling Fan Relay 1 Circuit High Input
P1500 - Radiator Fan Relay 1 Circuit Malfunction
P1501 - Idle Control System Malfunction (Fail Safe)
P1502 - Radiator Fan Function Problem
P1507 - Idle Control System Malfunction (Fail Safe)
P1510 - Idle Air Control Solenoid Signal 1 Circuit Low Input
P1511 - Idle Air Control Solenoid Signal 1 Circuit High Input
P1512 - Idle Air Control Solenoid Signal 2 Circuit Low Input
P1513 - Idle Air Control Solenoid Signal 2 Circuit High Input
P1514 - Idle Air Control Solenoid Signal 3 Circuit Low Input
P1515 - Idle Air Control Solenoid Signal 3 Circuit High Input
P1516 - Idle Air Control Solenoid Signal 4 Circuit Low Input
P1517 - Idle Air Control Solenoid Signal 4 Circuit High Input
P1518 - Starter Switch Circuit Low Input
P1520 - Radiator Fan Relay 1 Circuit High Input
P1540 - Vehicle Speed Sensor Malfunction
P1544 - High Exhaust Temperature Detected
P1560 - Back-Up Voltage Circuit Malfunction
P1590 - Neutral Position Switch Circuit High Input
P1591 - Neutral Position Switch Circuit Low Input
P1592 - Neutral Position Switch Circuit (MT Model)
P1594 - Automatic Transmission Diagnosis Input Signal Circuit Malfunction
P1595 - Automatic Transmission Diagnosis Input Signal Circuit Low Input
P1596 - Automatic Transmission Diagnosis Input Signal Circuit High Input
P1698 - Engine Torque Control Cut Signal Circuit Low Input
P1699 - Engine Torque Control Cut Signal Circuit High Input
P1700 - Throttle Position Sensor Circuit Malfunction (A/T)
P1701 - Cruise Control Set Signal Circuit Malfunction (A/T)
P1702 - Auto Trans Diagnosis Input Signal Circuit
P1703 - Low Clutch Timing Control Solenoid Valve Circuit Malfunction
P1704 - 2-4 Brake Timing Solenoid Valve Circuit Malfunction
P1705 - 2-4 Brake Pressure Solenoid Valve (Solenoid D) Circuit
P1711 - Engine Torque Control Signal 1 Circuit Malfunction
P1712 - Engine Torque Control Signal 2 Circuit Malfunction
P1722 - Auto Trans Diagnosis Input Signal High Input
P1742 - Auto Trans Diagnosis Input Signal Malfunction
the engine mod sticky..
and the suspension sticky..
and the aftermarket sticky..
or at the very least the aftermarket one so i can update it still
can a mod delete all of the stickies at the top of the forum EXCEPT the aftermarket parts and ugrade one....
then stick this one and the suspension FAQ located here
WAY too many stickies up there. I just condensed all of them into two different ones...and added a bunch of stuff
Nice good job i vote make this a sticky and lose some of the old ones...
I'll give all the specs from my build when It gets started.. frankinsubaru! :D
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