ECO mode - m/t

Just double post - this does not quite fit in Legacy Photos forum. Please take this as a guess at the moment, I want to ask Subaru/STi about it. In regards to the ECO mode on the manual transmission, I feel it is one of two things. The simplest one would be that when pressing the ECO mode button it switches over to another set of instructions for the DBW throttle, which reduces inputs from the throttle. This is tracked in conjunction with the new system for tracking fuel consumption. This only works for the first 20% of pedal travel - going beyond that, the Eco light goes off and it basically goes to "normal" for accelerating from lights/passing/hooning, etc. The more complicated option would be that it is switching to a completely new map in the ECU, one optimized for mileage over performance. I noticed that the engine actually sounds different between the two modes, which points towards it being No.2, and possibly to it actually modifying quite a few engine parameters, from the AVCS to the amount of boost available. It was noticeably more torquey and responsive even just cruising at 2500-3000rpm, comparable to the feel of a low-compression engine suddenly switched to a high-compression engine. Neat stuff. I will get some accurate information out of Subaru about this, because this may impact the tuning community quite a bit. If it has the ability to switch maps in the ECU, that means that it can store more than one map. It also means that it is likely to be a far more complicated ECU than in the USDM STi - reflash solutions may be a *long* way off. Cheers, Paul Hansen

[quote name='apexjapan']I noticed that the engine actually sounds different between the two modes, which points towards it being No.2, and possibly to it actually modifying quite a few engine parameters, from the AVCS to the amount of boost available. It was noticeably more torquey and responsive even just cruising at 2500-3000rpm, comparable to the feel of a low-compression engine suddenly switched to a high-compression engine.[/quote] iiiiiiiiiinteresting.... I bet it tweaks up the timing 5-10 degrees for better NA performance and then limits boost on the turbo to prevent detonation. That'd certainly help with mileage since most of the time while cruising you'd be at low revs, light throttle, and off-boost for the most part. Yeah AVCS tuning could be it too. At lower revs but under load you'd actually want some overlap between exhaust valve close and intake valve open assuming an NA engine. But under boost you wouldn't want that since it can bleed off boost. Being able to switch it to a "quasi" NA mode sounds like a neat but very useful trick if that's what it's doing. I bet the US version won't have it - because that's too complex for most people here. :lol: I hope it does have it anyways though. :) Steve

So I do not start too many threads, some additional notes somewhat related to gas economy. So far, I am averaging about 10km/liter in mixed city/expressway driving. That is about 25mpg, when keeping it below 4000rpm at all times and taking care not to full throttle often. On the expressway today, after filling the tank and resetting the tripmeters, it averaged 13 km/litre at speeds varying between 100 to 155km/h. That is about 63 to, um, 95 mph. And about 32.5mpg. While I was decelerating/accelerating due to engine break-in constraints towards holding revs. I think it may actually hit 14 or 15km/litre if holding steady at, say, 75mph. I do not think the USDM turbo will hit the same mileage - 2.5-litre motors are going to burn more than 2.0-litre motors - but 30mpg in steady-state driving should surely be achievable. It also feels like the first 4 gears on the 5-speed are fairly well spaced for acceleration, while 5th is geared for mileage. 4000rpm in 5th gear is about 158km/h - 98-99mph - while 4000rpm in 4th is about 120km/h. Cheers, Paul Hansen

That gas mileage is excellent. Even if the 2.5 turbo is a few MPG less than your 2.0 it would still be very good IMO. I'm hoping we get the ECO mode also but I don't recall seeing it on the GT at the auto shows.

I presume lean cruise is illegal ?

[quote name='EJ20H-TT']I presume lean cruise is illegal ?[/quote] What does that mean?

You can lean out the air fuel ratios when cruising. "Lean cruise means that fuel economy is better, so greenhouse gasses are less - but NOx goes through the roof. But if you think about it, it's only ever going to happen in the country or when you're cruising along at a steady speed. The problem with NOx is that it's bad for your visible emissions because it puts brown smoke in the air, but [at the same time] you're using less fuel and resources"

Interesting, never heard of it before.

[quote name='apexjapan']So I do not start too many threads, some additional notes somewhat related to gas economy. So far, I am averaging about 10km/liter in mixed city/expressway driving. That is about 25mpg, when keeping it below 4000rpm at all times and taking care not to full throttle often. On the expressway today, after filling the tank and resetting the tripmeters, it averaged 13 km/litre at speeds varying between 100 to 155km/h. That is about 63 to, um, 95 mph. And about 32.5mpg. While I was decelerating/accelerating due to engine break-in constraints towards holding revs. I think it may actually hit 14 or 15km/litre if holding steady at, say, 75mph. I do not think the USDM turbo will hit the same mileage - 2.5-litre motors are going to burn more than 2.0-litre motors - but 30mpg in steady-state driving should surely be achievable. It also feels like the first 4 gears on the 5-speed are fairly well spaced for acceleration, while 5th is geared for mileage. 4000rpm in 5th gear is about 158km/h - 98-99mph - while 4000rpm in 4th is about 120km/h. Cheers, Paul Hansen[/quote] I haven't reset the first tripmeter on my car since I got it. It has about 7.5k on it and I'm at 9.8 for avg km/l mixed city and highway. Thats on 2.0R (auto), I'm assuming you have the same model only in manual. Bear in mind I live on an island so the terrain is quite mountainous. While on a flat section of the highway I'm getting around 22 - 24 km/l while at 110 120. Any higher or lower in speed than that and there is a significant difference.

i Love the eco button!! it does remap the boost. and im pretty sure its fuel as well

 

i can tell the differce with it being turned on or off. the engine sounds different and revs harsher.

Im just in the process of asking the subbie guys in nz who i get my car stuff done if i can acutlly use that ECO button as a boost controller and run more boost or wht eva but they said they dont know as they aint seen a manual turbo with an ECO button.

They jst did my gear box and diff oil.. but now since thats been done my 3rd gear is really tite to get in when i rev it around 5 it kinda pops out.. so i have 2 go and ask them whats up with that.. n e one got any ideas. btw i got a 2005 legacy white sedan 2L turbo

Dave, I think you get the award for responding to the oldest thread

 

Kids in 5th grade for the previous post have now graduated from High School

my bad im new to forums and didnt look @ the date !

I am just playing with you Dave, Not trying to give you a hard time. This Forum is great, there are a lot of good guys here.

haha no problems nice 2 meet u

I've got a 2005 legacy 3.0R auto and it has an eco button. I like how it changes gear much sooner to keep the revs low. Does it change the engine mapping or AVCS as well? has anyone been able to confirm this? Also a friend of mine got a legacy recently and his eco mode doesn't seem to work, the light doesn't come on or anything. Got any ideas how to fix it?

When I run the ECO map from Cobb, which goes to a 'lean cruise' mode, getting the AF close to 15:1, and reduces boost to 1-6psi, I noticed ZERO improvement in MPG over the Stage 1 map.

 

At first I was driving long distance with only the ECO map, but after testing Stage 1 I never went back.

 

I wonder if the cobb map vs the subi map has a lot of differences?

Hey guys, am new to this forum and want to ask what can be the advantages of using the Eco button, does it saves fuel or ?. Thank you in advance for your responces.