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I have a 2012 I4 Terrain with right at 2k miles on it. A few weeks ago I noticed that the idle felt a little rough sitting at stop lights after the engine was warm. Not horrible, just bounced between about 450 and 650 rpm. I have driven it in ECO mode probably 85% - 90% since I picked it up in October.

I took it to the dealer to make sure everything was okay and their computer showed nothing was wrong. Target RPM & actual RPM matched, etc. I didn't notice that the tech turned off ECO mode when we took it for a spin to see if we could duplicate the issue (we could not).

They told me to call if it did it again and they would take another look.

On the drive home it was indeed fine. About half-way home I noticed ECO mode was off; I flipped it back on. The slightly rough idle returned!

If I'm sitting in ECO mode, the idle bounced between 450 and 650 rpm. If I turn ECO mode off the idle jumps to maybe 850-900 rpm and is very smooth.

Just curious, is this normal behavior as the engine tries to eck out as much efficiency as possible or should I head back to the dealer for this?
 

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Same experience here; slight rough idle in eco mode at idle. Sometimes the vibration is more pronounced than other times. Several automotive reviews I read prior to purchase, specific to the DI I4 engine, reported similar finding(s). I only use eco mode on the highway once I've reached cruising speed; I've noticed NO discernible difference in mileage with eco on or off for suburban (daily) driving. Idle in non-eco is 'silk smooth.' To answer your question, rough idle in eco mode is a known issue with this engine and manufacturer (not all owners report this problem, mind you). Regardless, its an unnecessary issue, IMHO. My other ride also features a DI engine (w/ sport and eco modes) and the latter setting in that engine does NOT produce rough idle when stopped, idling. Just one more facet that makes owning GM.....special.:p
 

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I agree with the roughness which is inconsistent in degree.My rpm's can vary from 600 to 900 at idle/stop lights.
 

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I would recommend returning to the dealer and having them take a look with ECO mode on. Please keep me posted on your progress and contact me with any questions. Thank you.

Tricia, GM Customer Service.
 

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Had same issue so i stopped using eco for 15k mi. Just recently turned it back in and i feel like i have more hp and smoother shifting and not that much idle roughness. I suggest if your nox is low mi. Leave it off for first 5k to 10k. Then turn it back on. It will feel like you have a car with more power on acceleration :eek:
 

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Discussion Starter #6
Tricia -

I'm going to take it back in 1000 to 1500 miles for an oil change and I'll have them check the idle with eco-mode turned on.

Thanks,
Jacob
 

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agree...ECO mode drops the idle, and it also shifts at different points than out of the ECO mode...

I found with my 2011, that ECO mode only really is beneficial while highway or freeway driving..I drove with ECO mode on for quite a while, didnt like the idling and the rough shifting..and Turned it off..and only used on the freeway..

I got maybe 1-2 MPG more in city driving with the ECO mode..in the long run it wasnt worth it to me..JMO.
 

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wrusprod said:
agree...ECO mode drops the idle, and it also shifts at different points than out of the ECO mode...

I found with my 2011, that ECO mode only really is beneficial while highway or freeway driving..I drove with ECO mode on for quite a while, didnt like the idling and the rough shifting..and Turned it off..and only used on the freeway..

I got maybe 1-2 MPG more in city driving with the ECO mode..in the long run it wasnt worth it to me..JMO.
My ECO idle RPM is about 600 and 750 non-ECO. Also notice that in city driving in non-ECO the RPM will be higher at 35 MPH or so in non-ECO, apparently due to not upshifte yet.
 

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Today I checked my 2012 I4 in ECO mode, engine warmed, at a stop, Transmission in 'D', idle was steady at 750 according to the dashboard tach
 

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wrusprod said:
agree...ECO mode drops the idle, and it also shifts at different points than out of the ECO mode...

I found with my 2011, that ECO mode only really is beneficial while highway or freeway driving..I drove with ECO mode on for quite a while, didnt like the idling and the rough shifting..and Turned it off..and only used on the freeway..

I got maybe 1-2 MPG more in city driving with the ECO mode..in the long run it wasnt worth it to me..JMO.
Our 2011 I4 Terrain also has a rough idle with ECO on. Why would there be any benefit to having ECO on at highway speeds?
 

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Do yourselves a favor and run the car with ECO off. Highway is really the only beneficial place to use it. Also, in my not so sceintific, nowhere near an engineer opinion, I'm not convince that running eco isn't harming things. Carbon buildup for example. I'm also curious if it plays a role in some of the engine problems we read about. So, for such little gain, it's ECO off for me.
 

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tsduke said:
Do yourselves a favor and run the car with ECO off. Highway is really the only beneficial place to use it. Also, in my not so sceintific, nowhere near an engineer opinion, I'm not convince that running eco isn't harming things. Carbon buildup for example. I'm also curious if it plays a role in some of the engine problems we read about. So, for such little gain, it's ECO off for me.
I agree..and have wondered the same thing about some of the engine problems.
When test driving the Equinox(several)..we tried ECO out of curiosity...but just couldn't quite understand the engine...tranny change in performance for a mere 1 more MPG. My wife has never used ECO and has had no problems with her Equinox. She has been getting 23-24 mpg city..and on a recent Christmas trip of several hundred miles broke the 30 mpg barrier with 31.4 mpg.
 

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Some say Eco is better for city, others say for highway. To me it seems like it would have more effect in city driving. The consensus is that it lowers idle RPM, causes earlier upshifts, and locks up the torque converter sooner, and also allows the car to lug more at low speeds. Further when accelerator is hard pressed, little to no observable difference is noticed in its ability to accelerate (some say poorly, either way) These observations by forum members (here and others) and the automotive press tend to support the above symptoms and reactions. Thus, it would seem like city type driving would benefit most.

Who knows for sure? And how did you measure it?
 

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Terrain2011 said:
Some say Eco is better for city, others say for highway. To me it seems like it would have more effect in city driving. The consensus is that it lowers idle RPM, causes earlier upshifts, and locks up the torque converter sooner, and also allows the car to lug more at low speeds. Further when accelerator is hard pressed, little to no observable difference is noticed in its ability to accelerate (some say poorly, either way) These observatopms by forum members (here and others) and the automotive press tend to support the above symptoms and reactions. Thus, it would seem like city type driving would benefit most.

Who knows for sure? And how did you measure it?
In theory and maybe design that would be true, but most forum members have found the gain of using ECO to be highway driving. On the highway, in ECO mode the car will hold in OD longer and maybe lose a bit of speed rather than downshift right away. I saw zero gain of using it in town on my first Nox, don't use it on my current Nox. Irregardless of the gains for city driving, it drives like crap with ECO mode.
 

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I had my 2011 Terrain I4 for one year and 28k miles..

I played around with the ECO mode a bit for a while.. I found the only time it really showed that it worked was on a long freeway trip...

city, i saw maybe 1 MPG, but had to deal with the idle issues, and shifting issues...finally just turned off the ECO and didnt use it again..
 

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Besides the annoyances numerous people have already stated, has there been any noteworthy mechanical issues that can be attributed to leaving eco-mode engaged all the time?
 

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jdubs1211 said:
Besides the annoyances numerous people have already stated, has there been any noteworthy mechanical issues that can be attributed to leaving eco-mode engaged all the time?
I have had mine in ECO mode for almost 2 years, and haven't had any mechanical issues from this, nor even any minor annoyances. But, i also don't know if it has improved the gas mileage - the green light just makes me feel "green". ::)
 

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I have a 2012 I4 FWD and I have not noticed this problem at all. It sits around 600 rmp when sitting idle and stays there. Build date on mine is December 5, 2011
 

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RIT333 said:
I have had mine in ECO mode for almost 2 years, and haven't had any mechanical issues from this, nor even any minor annoyances. But, i also don't know if it has improved the gas mileage - the green light just makes me feel "green". ::)
One year here, but +1
 
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