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2014 Forester Manual
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8 Posts
Discussion Starter · #1 · (Edited)
Hi,

I have a Forest 2014 2.5i manual shift version. And I found the rpm of the engine is not constant (changes back and forth between 500-1000 rpm) when the engine is idle and the shift is neutral. Is it normal phenomenon?

Thanks in advance.
 

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Premium Member
2019 Crosstrek 2018 Forester XT
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14,922 Posts
If it goes up and down with that swing in rpm's its a problem. If it just starts high and gradually lowers to some value and stays there, that's OK. Perhaps you have the A/C or defrost on, which could cause this.
 

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Premium Member
2008 Forester X Premium 5MT
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8,064 Posts
It is normal.

Especially if the AC is on, as the AC compressor engages the engine needs to kick the idle up to accommodate for the larger load now being driven. The AC is also on when the HVAC dial/s are set to defrost.

Low idle is about 625-675 and high idle around 725-800.

The gages are in reality just reference gages, even more so at low RPM/speeds. They are not highly accurate calibrated instruments.
 

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2004 Forester 2.5X 5 speed manual
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2,136 Posts
Be safe and have the vehicle checked out. The RPMs on my 5mt Forester only change by about 200/250 RPM when the AC cycles on/off at idle. Granted, my Forester is just over ten years old, not exactly a 1:1 comparison. And you didn't indicate how long you've had your 2014 or how many miles it has, so your Forester could still be in the learning phase of the break in period, in which case it will seem to do some odd things from time to time (like occasionally run unnecessarily fast).
 

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2014 Forester Manual
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8 Posts
Discussion Starter · #5 · (Edited)
Hi,

Thanks all of you for your replies.

My Forest is pretty new, it is only 1 week and 200 miles.

So maybe it is still too new to get constant?

Do I need to wait some time before I go to check my engine?

BTW, the change of rpm is not rapidly. It is more like changing from about 1000 smoothly to about 600 (within several seconds) and goes back. And I do have my AC on because of the cold weather recently.

Thanks again.
 

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2004 Forester 2.5X 5 speed manual
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2,136 Posts
Only one week and 200 miles? You are early in the break in period and learning curve (both yours and the vehicle's). If it otherwise runs OK, isn't burning oil, and isn't throwing the 'check engine' light, then maybe wait until 1000 miles to reassess RPM changes and see if it needs a trip to the shop. It should start to slowly get better. Also note that the cold weather right now isn't helping. Probably should wait and see how it operates once more moderate weather returns. My Forester does OK in cold weather once it is warmed up. Until it warms up it can be quite ornery.

If no noticeable improvement or it's worse by 500 miles, however, probably best to have the dealership go ahead and check it out.
 

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2014 Subaru CVT
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2 Posts
Ours does the same thing; a 2014 2.5i Premium that we just got two days ago ~ 110 miles. Took wife to toysrus for some shopping and waited in the car programming the bluetooth and noticed the same thing sitting in the parking lot idling, heat on, lights on, radio on, no AC. I really don't believe it is a problem, I believe it does that on purpose. I don't know exactly why, but it could be for charging battery or because of low hours on engine etc. Now on my 01 Cherokee it would do that on start and worse, say up to 2000rpm which is indicative of a problem so I changed out the idle air control valve and throttle position sensor to fix it.
 
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