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CovertRussian's 05 LGT Build Thread


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I've been driving without an undertray since I ran over a deer with the car couple months back. I got a long trip coming up which will probably have snow to fight through so figured I would quickly fix up the pan. Eventually I plan on doing a real skid plate...

 

$2 of zipties and a drill go a long way :lol:

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Exterior/Undertray/20141124_220856.jpg~original

 

Looks like the black forest...

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Exterior/Undertray/20141124_220937.jpg~original

 

After cutting the ends off, doesn't look toooo bad :spin:

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Exterior/Undertray/20141124_221134.jpg~original

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Exterior/Undertray/20141124_221139.jpg~original

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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I plan on making it a little more durable and without theft :-D

Best part though, they're not stolen. Friend of mine owns a few acres, and we found these and others that were torn, and abandoned. So I thought, why not.

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Nice, that works even better then. I am planing on making them out of decent thickness aluminum and then use oem tray for aerodynamic enhancements.

I'm interested. I'm doing the same thing on my build.

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Cross posting this from the ECU Tuning for Fuel Economy thread, since it's useful to have this info in the build thread too.

 

I noticed my fuel economy would drop with ambient temps falling below 60*F. In one day I lost 3 hwy mpg just between driving in morning and night. Thus I've been looking for the culprit in the tune.

 

Traveled about 800 miles yesterday and had a chance to play with the tune. While I was expecting and hoping for cold weather for testing the below 60*F MPG drop, weather turned for the worse with snow and traffic. Both of those really mess up the MPG averages and make it hard to do consistent drives.

 

Quick Glossary:

IAT = Intake Air Temperature

TMIC = Top Mount Intercooler

AVCS = Active valve control system

 

 

Intake & TMIC Blocking to increase IAT

I wanted to first try to get higher IAT's reducing the efficiency of the airbox and by blocking the intercooler. If your going to make the intake less efficient you need to also make the intercooler be less efficient. Sadly the IAT sensor is part of the maf before the turbo or intercooler, so it's readings can be way different from actual post intercooler temps. This is why I had to block both to increase temps.

 

Removed stock ram air plastic, and setup a cardboard block, which should stop fresh air from front form going into the airbox.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Engine/Intake/General/20141125_191745.jpg~original

 

Blocked the intercooler, this increased the intercooler temps to be about 20*F warmer.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Engine/Intake/General/20141125_185357.jpg~original

 

Stock scoop does have holes for sending cold air to the turbo, which I didn't block.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/Engine/Intake/General/20141125_185429.jpg~original

 

Data

Ambient Temp: 37*F

IAT's: ~50*F

TMIC Temps w/Block: ~60*F

TMIC Temps w/o Block: ~40*F

Conditions: Wet/rain, no snow

Road: I64 West VA, but after the mountain peaks

AVCS: 10*

Timing: ~46* @ 70mph

MPG: 24.39

 

Conclusion: the cardboard blocks didn't help, they might have actually hurt the fuel economy.

 

Fool the ECU to think it's 70*F IAT

I completely forgot that I could just fool the ECU into thinking it was warmer weather by messing with the sensor scaling. This would help me see if an IAT based compensation table at fault for lost fuel economy. For this I returned the intake system to stock (with ram air plastic) and removed all of the cardboard.

 

Stock vs Modified IAT Scale

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/IAT%20Comp/05LGTIATSensorScale.png~originalhttp://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/IAT%20Comp/IATScaling70F.png~original

 

Data

Ambient Temp: ~40*F

IAT's: ~45*F

TMIC Temps w/o Block: ~40*F

Conditions: Dry & Sunny

Road: I64 Kentucky

AVCS 10*

Timing: ~45* @ 70mph

MPG: 28.28

 

Conclusion: I think that actually worked! Which means the cold weather MPG drop is probably mostly ECU related. Car didn't feel like it was racing, it was driving similar to 60+ weather.

 

 

AVCS 20*

With this test I returned the IAT scale to stock and wanted to see if more intake AVCS would help. I went extreme with 20*, which with stock downpipe had yielded me some of the better economy.

 

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/AVCS/AVCS20v3.png~original

 

Data

Ambient Temp: ~40*F

IAT's: ~45*F

TMIC Temps w/o Block: ~40*F

Conditions: Dry & Sunny

Road: I64 Indiana

AVCS 20*

Timing: ~46* @ 70mph

MPG: 26.78

 

Conclusion: While this definitely was better economy then the first fillup, it was still falling into the same under 27mpg below 60*F trend. Perhaps less AVCS (15*), would help, but I doubt it because learning views at 20* were clean.

 

 

Zeroing IAT Compensations

Since messing with IAT's helped more then more AVCS, next run I decided to see if I could zero out the compensations and see if economy improves. Four tables that use IAT based compensations are Wastegate Duty Comp A&B, Timing Comp, MAF Comp.

 

Stock IAT based compensations:

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/IAT%20Comp/05LGTStockIATComps.png~original

 

Zeroed them out for the temperature ranges that I was in.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/IAT%20Comp/IATCompsZeroed.png~original

 

Data

Ambient Temp: 42*F to 33*F

IAT's: 47*F to 35*F

Conditions: Cloudy & Snowing for 1/2 miles, traffic

Road: I64 Illinois

AVCS 10*

Timing: ~46* to 47* @ 70mph

MPG: 25.29

 

Conclusion: First 60 miles were dry smooth sailing, next 80 miles were not so good. First it started heavily snowing, but roads were not bad. Then I hit 1hr of 1mph traffic, that go me about 20 city miles which at 17 mpg really kills your averages. Thus I was impressed to see even 25mpg. Thus I'm now sure it's one of the 3 compensation tables that are at fault. Car also didn't feel like it was racing, like before.

 

Update: Zeroing the IAT comp tables didn't seem to help, got 26.91mpg at best on a more consistent highway trip. Thus it's either another table or another non tune variable.

 

 

Overview of the 4 Compensation Tables

Timing Compensation (IAT):

This table adds 1.05* at 50f and 2.11* at 32f. I personally don't think it's this table at fault, because stock timing is 40* and I saw this MPG drop with running 41* timing before. In this case I'm running 45-47* of timing.

 

Initial/Max Wastegate Duty Compensation (IAT) A & B:

These tables start to remove -4.7 duty cycles at 50*F. Which means between 50*F and 68*F they will be interpolating and removing less duty cycles and hitting 0 by 68*F.

 

I think it could be this table at fault, by removing initial and max duty cycles, the car might have to work harder to keep it going the same speed, which means more throttle has to be used. The thing that trumps this theory though, my Initial and Max duty cycle tables beings at 0 until 24% throttle. Logs show that I'm at 14-18% throttle at 70mph.

 

MAF Compensation (IAT):

This table didn't really catch my eye for a while because I wasn't reading it right and logging Mass Airflow. On one of my highway logs my average Mass Airflow was 30 g/s. Which means that at 32*F ECU would be pulling about 1% of fuel. That means at 50*F in theory the ECU will be pulling 0.5% of total fuel.

 

This plus colder denser air could be causing the engine to lean out, which means powerloss thus needing more throttle for same speed. But the O2 sensor should be correcting for this and keeping AFR's at 14.7.

 

 

I'm open to comments and suggestions, I will be driving back another 800 miles next week and will be trying to find the culprit table :lol:.

Edited by covertrussian

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Have you considered doing the GM style IAT sensor relocation to the TMIC outlet? Seems like a no brainer. Having the stock TMIC complicates matters some, since you can't easily weld a bung. This mod increases accuracy of ecu scaling under any circumstances. Edited by Cincy05LGT
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Rear O2 Compensations Zeroing

 

Most people see a pretty bad MPG drop when they would go to a catless downpipe (or catted but rear O2 is before the cat like in factory configuration). This is because 32bit Subaru's also use the Rear O2 sensor feedback to adjust the fuel trims. Without a cat infront of the Rear O2 sensor the readings will be leaner (O2 sensors read oxygen content, catalytic converts burn up oxygen along with fuel), which will make the ecu constantly add additional fuel.

 

 

On my 04 Forester XT with 160k miles, with stock downpipe but catless up pipe I gained around 2MPG in the city from this change! This could be because I have 1 less cat then what the car was meant for, or because of exhaust leaks, or because of a worn out rear O2 sensor. Either way I was pleasantly surprised to hit 20mpg city, when before I would get 17-18.

 

 

Rear O2 Compensations consist of two tables, AF 3 Learning Limits and AF 3 Correction Limits. The factory tune allows the AFR to be swayed from -0.5 to 0.5 lambda, in AFR speak it can sway the tune by 7.35AFR in any direction! This can be seen in the top images below. The second set of images shows those tables being zeroed out so that ECU can't adjust the fuel mixture based on the Rear O2 sensor anymore.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/Rear%20O2/AF3CompsZeroing.png~original

 

 

Sadly these tables are not defined in RomRaider or EcuFlash by default, your gonna have to find the table hex numbers and create new tables in EcuFlash. Refer to these two threads to find the proper values for your ECU.

AF#3 (Rear O2 sensor) correction limits

Rear O2 sensor closed loop fueling target limits

 

For O5 LGT A2WC522N Use:

AF3 Correction Limits - 2DF2C

AF3 Learning Limits - 2C91C

 

For 04 FXT A2ZJ5I2I Use:

AF3 Correction Limits - 293C4 (Stock Correction limits will be in percent; High: 50.00%, Low: -50.00%)

AF3 Correction Adder - 5D558 (Stock Adder limits will be High: 0.000500, Low: 0.000350

Edited by covertrussian

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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  • 3 weeks later...

Did more testing with the zeroed out IAT compensation tables and it seems like they are not the culprit. Going to the city that I usually go to for MPG testing, I got only 26.91mpg with IAT comps zeroed out. The three tables I zeroed out are not at fault, doesn't mean it's still not the tune, but I started looking at tires.

 

I've been keeping the tire pressures cold at 36/34psi at ambient temperature (adjusting them when temps go up or down). At 35*F they warm up to around 39.5/38psi (front/rear) after highway driving which got me 26.91mpg last weekend. This weekend I went to the same city and the only thing that I changed was tire pressure to 42/40psi cold, they warmed up to 45/43.5psi at 37F. This got me 28.72mpg at the pump (not the gauge which was way off). This is the best cold weather MPG I've ever gotten to this city, thus I believe colder tires are carrying the 50% of the MPG loss, the other 50% is probably tune and extra drag.

 

Here is my current theory on why below 60*F temps drops the gas mileage. 1.Tires, 2.Denser air = more aerodynamic drag 3.Colder fluids = more mechanical drag.

 

Tires heat up and air expands as you drive up to a certain point. With colder ambient temps, tires don't get nowhere near as warm as they would on warm day. So far the car seems to like about 45psi warm and starts getting better gas mileage. This makes sense since AWD means more drivetrain loss, thus reducing the rolling resistance as much as possible helps more then on a more efficient drivetrain setup.

 

I've been measuring tire pressures right as I stop before they start cooling down and writing them down for reference, sadly I only started doing this after it stopped being warm, thus will have to grab warm numbers before summer gas goes back in and adds another variable.

 

Cold 36/34psi, warm 39.5/38psi at 35F.

Cold 42/40psi, warm 45/43.5psi at 37F.

 

I believe 36/34psi cold tires would be closer to 43/41psi on a 60*F day. Another interesting variable, front tires tend to raise less then the rear tires on a cold day. I believe this is because front tires are exposed to more cold air then the rear tires which have air deflectors and front tires as air deflectors too.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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  • 2 weeks later...

More testing, this is to another city 2hours round trip. This one involves going over a 2,00ft mountain, thus adds another dynamic for MPG testing. While going through West VA, I got abysmal MPG's, and I wanted to see if closed loop to open loop delay being disabled was to blame.

 

Usually going to this city I would get 26-27mpg with temps below 60F with tire pressures at 36psi front and 34psi rear.

 

City A

Tune: Closed Loop to open loop delay on, 3 IAT comp tables zeroed out

Timing: 40* stock timing +0* IAT comp

Ambient: 48-55F

Cold Tire PSI: 42f/40r @46f

Warm Tire PSI: 48f/45.5r @55f after 60m

Dash Gauge MPG: 27

Pump MPG: 28.40mpg @ 70mph

 

City B

Tune change: Closed Loop to open loop delay off, Stock IAT comp tables

Timing: 40* Stock timing +2* from IAT comp table

Ambient: 38-48F

Cold Tire PSI: 42f/40r @43f

Warm Tire PSI: 47f/45.5r @48f after 60m

Dash Gauge MPG: 26.4

Pump MPG: 29.23mpg @ 70mph

 

29.23mpg is my personal best winter round trip mpg so far and it's my best MPG ever to this specific city, even my summer MPG to this city was 28.05mpg at best.

 

Thoughts about CL to OL Delay:

I don't think the open loop delay being on (OEM tune has it on) helped at all. I always here WRX guys saying that disabling the closed loop to open loop delay would cost them mpg's, but in my personal logs with non aggressive driving I see no difference or an actual improvement.

 

While going straight up the mountain at 70mph, my boost gauge would sit at 0psi a lot, but it would rarely get into boost, but since this is only a 2,000ft mountain. West VA ones go up to 3,500ft easily, thus I do remember those getting into more boost, which is where CL to OL Delay would cut back the amount of fuel used.

 

Another thought on why disabling the delay actually helps, less fuel means less torque, less torque means more throttle for a longer period of time. By having the delay be always off, you run a little richer but you make more torque thus you use extra throttle for a shorter period of time.

 

 

IAT Comp Tables:

I hate to introduce multiple variables, but due to cost of gas and cost of time, sometimes have to test changes in bulk and then dissect them to see what helped or didn't help.

 

Since this is a round trip run, any mpg gained from downhill terrain you loose when you go back uphill. When I was testing the IAT comp tables initially, it was all one direction, thus I must have hit a nice downhill patch through one of the states that made it seem like IAT comp tables were at fault.

 

Thus I can comfortably say that IAT comp tables were not to blame for the winter MPG downspike, I'm pointing my finger to tire pressures as the culprit. :lol:

 

Tire Pressures

There are plenty of magazines that tested tire pressures and said on their xyz skinny tire cars increasing tire pressure made no difference. I do believe that my tire size (225/45/17) and tire tread (Cooper RS3-A) is probably the reason why the car suffers such drastic cold weather MPG drop. My Nissan runs 195's and I've never seen such drastic MPG difference between different tire pressures, but it's also FWD and has much less drive train drag.

 

So far it seems like the best MPG comes from warm tire pressures of around 43+psi.

 

Dash MPG vs Pump MPG

I added in the dash MPG in for kicks above, but it made me see another trend. In cold weather when ever my real MPG would get above 27mpg, the dash always underestimates, but if my real world mpg is below 27mpg the dash is usually optimistic. If I recall correctly, the dash mpg gauge works of injector duty cycles. The higher your duty cycle the more fuel you use, which is not wrong. But it seems like in real world, more fuel in right areas can actually mean lower overall consumption.

 

Using more fuel can also be attributed to higher throttle body opening, which reduces the engine's pumping losses (same way intakes and exhausts help with power increase). While in closed loop, your O2 sensor will adjust your air to fuel ratios to 14.7. As you add more throttle (more air), O2 sensor will tell the ECU to flow more fuel to keep the mixture from leaning out. When ECU tells the injectors to flow more fuel, injector duty cycle increases.

 

This is why you can't rely on the dash mpg gauge for actual testing. Sure fuel pumps have errors too, but you can minimize those by using the same exact pump and filling up the same exact way.

 

 

 

Sorry for the long post, I'm pretty stoked to finally get 29mpg in the winter, especially on over the mountain trip. Now that I know that tires were the main culprit with the winter MPG loss, I can move onto testing various AVCS, Timing, and Fueling changes to see what helps most.

Edited by covertrussian

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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  • 2 weeks later...

Made a key for the three cities I drive to test round trip fuel economy (since single location driving has inconsistent terrains on the East Coast).

Driving Location Key

City A = Front Royal VA, 130 miles roundtrip, Rountrip Elevantion: 1300 to 600 to 1300ft

City B = Charlottesville VA, 120 miles roundtrip, Rountrip Elevantion: 1300 to 2000 to 600 to 2000 to 1300ft

City C = Winchester VA, 150 miles roundtrip, Roundtrip Elevation: 1300 to 700 to 1300ft

 

 

-------------------

 

Went to City A yesterday, got 29.44mpg, 45-46* Timing @70mph, 38-48F, Tire PSI 42/40@38F, 440lbs additional weight (to the base car weight), similar temp ranges. Two changes, fresh 5w30 synthetic oil (Valvoline) and AVCS set to 10*. Last week I went to that city, I got 26.37mpg, 260lbs, 46* timing, AVCS 0, 38-42F, Tire PSI 42/40@38F, Shell Rotella T6 5w40 (3300miles in).

 

On T6 the best mpg I've gotten to City A was 28.72, 440lbs, AVCS 10*, 36-37F, Tire PSI 42/40@37F, but that was with 41* max IGN timing at 70mph. I have gotten 29.23mpg to City B on T6 and 42* timing. Thus I don't think T6 had as much to do with the gain as just going from AVCS 0* to AVCS 10*.

 

I hate to have multiple variables for testing, but realistically it's very timing consuming, and expensive, to test only one change at a time, plus the weather is never 100% same (who knows about the wind speed differences haha).

 

Overall car seems to like AVCS 10 more then 0 with the downpipe. I'm tempted to try out AVCS 5-7* and see if it likes it more. Luckily gas is cheap and it costs me $10 to go roundtrip...

Edited by covertrussian

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Are you monitoring knock when you test?

 

I do pull learning view logs after every trip, and all of them has had 0 knock in all ranges in the last couple months of driving. They look similar to this:

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/AVCS/LWAVCS10Cruise130miles.jpg~original

 

The only time I've seen any knock was running AVCS 30* with the stock downpipe.

http://i160.photobucket.com/albums/t188/covertrussian/Cars/05%20LGT/ECU/AVCS/LWAVCS30Cruise130miles.jpg~original

 

I'm starting to tune the car for stage 2 powers, and I will redo my learning view scales to be a bit less combined then they are stock.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Some updates, been mainly driving the car because my Forester and turbo Nissan has needed mechanical love. But here are some updates

 

  • I noticed that switching back to Valvoline Synthetic 5w30 pretty much eliminated cold piston slap. It was getting pretty annoying with T6, not sure I'll go back to T6.
  • Noticed also the car is running 13-14psi max in cold weather. Need to fix my IAT based WGDC table to reduce it back down 11-12psi that it runs at 60*F.
  • Since I do most of my virtual dyno pulls in 2nd gear, I figured the engine doesn't spend enough time to run 13.5psi stock targets. Did a 2nd gear and 3rd gear pulls, noticed that 2nd gear actually boosts higher then 3rd gear. 2nd gear hits max 13.8psi@3379rpm, 3rd gear hits max 13.06psi@3806rpm. Thus still not sure why even 100% stock car only ran 11-12psi.
  • Clutch is starting to slip in cold weather :spin::mad:

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Funny you mention the clutch slipping in cold weather.

 

Both my cars do the same thing until they are fully warmed up. The Spec has a stock clutch with 63,000 miles. The wagon has about 45,000 miles with the Spec 2 clutch.

 

Yesterday getting on the highway on the up hill climb temp gauge was about a 1/3 up the red line, I rolled into the throttle a bit from about 60mph, not much may be 2/3rd throttle. The clutch slipped. 25 miles later I dropped it into 4th gear from like 60mph, went to WOT and all was fine. Air temp was 11F.

 

 

Last week from a stop light, the wagon easily spun the all 4 tires for about 50ft with only about 2/3 throttle and 3500rpm. Felt the back end slide to the right a little.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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I can see that, clutch is like brakes, they need to be warm enough to work better. I felt the slipping in 4th after the car was fully warmed up, but doesn't mean the flywheel it self was warm enough. Plus being a dual mass flywheel, heat probably doesn't transfer as well to the surface as a single mass one.

 

I've been considering selling the car and getting a newer LGT. Something something, folding seats and less rust would be nice.

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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My clutch is already on the way out, and the cold doesn't help it either. Talk about driving like a granny until it's warmed up. Forget about 4th & 5th gears, any amount of boost and it just spins. Just have to baby it 2 more weeks.
My wife's balls are delicious.
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