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Discussion Starter · #1 · (Edited)
I have heard some stories about ECO being really ECO or not at all.
From my observations it seems like ECO affects shift points and torque converter lockup clutch.
Basically shifts take place a bit sooner and the torque will lock almost in instant after the shift.

In non-ECO you will experience shifts at higher RPM (and higher speeds) and the torque will not lock this early. For example, 6th will kick in at slightly below 40 mph and torque will lock right away (ECO) making RPM to be roughly 1400. For non-ECO it will shift above 40 mph and torque will not lock until about 45 mph.
Downshifts are about the same.

Now, from my previous experience the best fuel economy would be in lower RPM range. Lower meaning 1500-2500 rpm. Maybe 2800. Going over 3000 would start drinking too much. Also, WOT or partial throttle - actually did not make so much effect.
BUT that was for NA engines!! That is not true for Turbo, though.

My suspicion for ECO and Turbo is that the same ECO algorithm was applied to Turbo engine as they used for NA versions. While for NA it works OK, Turbo not really.
Why? Well, because if you lock torque at 1400 rpm and need to accelerate, you need to produce more torque. Sure, NA would do the same, but when the turbo starts kicking in (and it does kick in more in ECO than in non-ECO), it makes the engine run richer. Hence, worse fuel economy.

This correlates with my findings.
In my everyday city driving (work and back) I noticed that in ECO I could not go over 25-26 MPG (from the display, not calculated). With ECO OFF, I can get to 28 MPG. Same conditions, same driving style.
One point though - it is to know that the ECO would work in similar fashion if you were every gentle with gas. Meaning, not allow turbo to spool too much.

I personally though ECO would be better, because you do not drop about 30-40% of power into slushy box (meaning ATF would absorb all wasted power when the torque is not in locked up position). Yet, that is not entirely true. Well, it is, but what happens is that the energy wasted in higher rpm is lesser than gained in locked torque converter only because to achieve same acceleration in ECO you need to run richer mixture (more turbo).

As for other aspects - as acceleration and reaction - I would say they are about the same.

I guess that's enough for ECO.

Now a bit about tune.
Before I got tuned, the best highway fuel economy I got was about 29 mpg (calculated on round trip at about 65 mph). Same day, so conditions roughly same. That was at about 8'000 miles ODO.

After tune, on 93 octane (US octane...), and basically stock car (no FMIC, same turbo, only intake KN drop currently) on same type of trip I got 35 mpg. That was at about 16'000 miles ODO.
The question one would pose - is tune worth for the fuel economy itself?

Well, not really, I think.
Why - because overall the numbers will drop as you will not be able to resist the urge to feel the extra power. Passing in 4th gear from 40 mph to 80 mph is just awesome. Or in 3rd from 30 to 60... or spinning wheels in 2nd gear all the way to 40 mph.
But if you can resist - then you are coming out pretty much even.
It is about 20% increase. I bet some other factors play in here, but well, it is what I got.
Petrol, 87 is say 3.00 per gallon, adding 20% will give you 3.60. Mine 93 is about 3.45, so I get not bad.


I forgot to add one more thing.
Since I got this nice 35 mpg calculated on about 200 miles trip while going no more than 65 mph, I decided to see how it would be if I was way more aggressive.
Therefore, on a very similar trip, about 250 miles, I was going a bit over the limit, like 78 mph to 85 mph in some places.
Oh well, I did not refill yet, but the display gave me 27.8 mpg. Knowing its about 5-10% error, I would say we are talking about 25 mpg calculated.
So there you have it.

13 Posts
I can say since I got my tune, I have not used ECO mode once. My gas mileage has gone down quite a bit. But I have been pretty heavy on the throttle, feeling the power!! Although. The tuner and I are still trying to work out an issue with the tune where it puts the car into “limp mode” during WOT pulls right after the shift from 2nd to 3rd

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534 Posts
ECO mode should also affect max throttle in some cases and also tip in speed, cam timing, timing as well as boost regulation and in some Kia models a/c and steering.

So to break it down
Tip in: throttle will no longer be at a 1:1 ratio but rather a 1:0.85 for example. This means that as you push on the throttle you push on the throttle the TB will open less are the same input signal. Monitor pedal position and throttle position to see what I mean. Another way it could modulate it is to make it more linear the further you push the throttle. So the further you push the throttle down the closer you get back to that 1:1 ratio. On the optima with a sport mode it actually changes this to open the throttle faster so less granularity but quicker response

Throttle: max throttle still only opens the plate to 85%. This in some cases could be less in eco mode.

Boost: could be electronically controlled to boost less on eco. I don't have an auto on my forte. But in the optima the boost feels more explosive than smooth in eco. Normal and sport feel much smoother on boost delivery. This one is a bit more complicated to explain but basically it would try to keep the car out of boost as much as possible. The time probably affected this btw

Cam timing and timing:. These would be assist for better combustion, hotter egts, etc. To ensure a more complete combustion.

A/c: turns out the compressor at certain times. Not sure this applies to the forte but it does on the optima.

Steering: it's electric so your thinking it does not have a pump so no load on the engine. Incorrect. Electrical load still causes drag on the alternator. So you will get less assist. This one maybe not be in the forte but does apply to the optima.

Now for the tune part. A factor thine for fuel economy is not always the most economical cause it's usually rich and not very efficient for part throttle. Also usually above a certain point (seems to be above 3k on the forte) your can profile will change and start making your car thirty. These cars are not very good for mpg though due to the gearing mostly. My MT which is geared worse than the auto does over 3k aft 80. Best I can get is that same 25-27 at that speed with family in the car for a road trip. However the optima which is heavier, has wider tires at 235, a bigger motor with it's 2.0 turbo, and is bigger drag against the wind gets 33 ish in normal mode, and a bit less in sport due to the delayed lock up of the torque converter and release of it every time you let go of the throttle.

Hope that helps and as usual if I'm mistaken in any of this please correct me.
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