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Discussion Starter #1
Hello

I have browsed through the various topics on this and have been unable to find a conclusive solution to the problem.

We have a 2012 Terrain 2.4l AWD with approx 140,000km on it.

A few months ago the vehicle began to idle rough when stopped, it has progressively been getting worse.

It began only in eco mode when stopped, and only from time to time. It has now come to a point where it happens frequently. Trends we have noticed are that it does not happen when the motor is cold and only after it has warmed up, it only begins approx 7 seconds after coming to an entire stop. Switching out of eco mode will reduce it and shifting to neutral will make the issue go away.

This is a rough idle to the point where voltage will fluctuate (lights dim), the car will also rock back and forth. On rare occasion the rough idle is so severe that it causes the engine to stall.

We have ran injector cleaner through, replaced both VVT Solenoids and cleaned the MAF sensor.

I am now at a loss for what some of the possible issues may be, thoughts would be a faulty MAF sensor, possibly O2 sensors. However the car runs perfectly fine under any other conditions which leads me to not suspect the MAF sensor.

I have looked at the readings on a few sensors, the part of the graph circled is during rough idle.

Any insight into this would be appreciated, shops we have had it in to so far have been unable to diagnose the issue . No codes are being thrown.

Thanks
 

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Discussion Starter #4
Thanks, that has also been done already.

Other things to note. The vehicle is a previous write off so as a result there is no warranty and is not eligible for recall.

Have monitored the oil consumption on the vehicle and it does not fall within the guidelines that would have qualified it for the recall, if it was eligible.
 

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Throttle body position sensor?

Your throttle position graph shows variation when you are having this issue, but is very smooth when you are not. I would think when you are stopped, the throttle position would be most stable.

Just a thought, as I am no mechanic.
 

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Discussion Starter #6
I had not thought about that one but could be a possibility, sensor just happens to be glitching out at a certain throttle position.

I was leaning more to that being a result of the issue. I was thinking MAF sensor originally as if this was malfunctioning it could cause an imbalance in the air/fuel ratio, which affects the rpm at idle. Then in turn it is sensed that the engine is not running at the proper rpm so the throttle is adjusted to compensate.

But if the position is not being relayed properly that could cause the RPM to fluctuate and give the same result with constantly trying to correct.
 

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Hello .. .. could this be related to your previous problem?

Did that ever get fixed and what was the remedy?

Looks like a part of the air box is missing, going to get this fixed and see if it solves the problem
 

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Discussion Starter #8
Hello .. .. could this be related to your previous problem?

Did that ever get fixed and what was the remedy?
Yes this was fixed.

Appears the shop that did the repairs post collision did not connect everything. Pulled the airbox out and everything was just sitting there, re connected it all and problem solved
 

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Discussion Starter #11
Hello. I have this identical problem on my 2011 terrain did you solve the problem?

Problem has ceased when the weather got cold. Has not been happening since late fall. Will see if it starts back up again when it warms up this spring. But have not changed or fixed anything that resulted in the problem going away.
 

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Hello. I have this identical problem on my 2011 terrain did you solve the problem?
Jpell - what engine do you have and how many miles on your vehicle and where do you reside ? If the 4 cyl., are you using Eco mode ? If so, you may want to disable it, and see if that helps ? Have you ever cleaned the throttle body/MAF sensor ? Have you ever changed the spark plugs ?

Sorry for all the questions, but in order to provide a quality answer/suggestion over the Internet, there are many unknowns that need to be known.
 

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I thought I’d bring this thread back to life. I have a 2013 2.4 with 90k on it. Ever since new mine has had a very rough idle only in the summer when the AC is engaged. I’ve noticed that the warmer it gets the rougher the idle. Turn off the AC and it smooths out. My theory which I have yet to look into has to do with increased Head pressure in the AC compressor. On a super hot day I may bring it into a shop and have them check pressures.

For those curious I routinely clean the MAF and TB. I have done a tuneup and changed out both camshaft actuators. 4K full synthetic oil changes and every 4k either Seafoam or Techron in the gas. I have also changed the belt and tensioner.
 

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As a guess.....
if the battery is more then 3 years old, buy a new one....

And 2 cents,
Never use eco mode, it increases LSPI, which will get you to burning oil faster....
And don't forget to check oil levels with dipstick frequently
 

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I thought I’d bring this thread back to life. I have a 2013 2.4 with 90k on it. Ever since new mine has had a very rough idle only in the summer when the AC is engaged. I’ve noticed that the warmer it gets the rougher the idle. Turn off the AC and it smooths out. My theory which I have yet to look into has to do with increased Head pressure in the AC compressor. On a super hot day I may bring it into a shop and have them check pressures.

For those curious I routinely clean the MAF and TB. I have done a tuneup and changed out both camshaft actuators. 4K full synthetic oil changes and every 4k either Seafoam or Techron in the gas. I have also changed the belt and tensioner.
Check the o2 sensors, similar problem on my 12 2.4 w100k miles. Bank 1 was destroyed. I had no codes.
 
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