1 day old '05 Forester idle not steady

[Guest]

Hi,
Just drove my brand spanking new '05 Forester home today. When I parked,
before turning off the engine, I sat there just soaking it in. And I
noticed that when idling, the idle has a pattern in which it goes up, then
back down, then up, then back down. All by itself.

When idling I would think the idle should be steady. Any thoughts on this?
Yes, I will be calling the dealer, but am looking to hear if anyone else has
experienced this?

Thanks!
Rogue Petunia

 

[schema]

Curious, Is the AC switch on?

 

[Henry Paul]

Or the defroster for that matter?

 

[Rogue Petunia]

Hi Henry and Schema,
That thought crossed my mind. I can't remember. I will drive the car again
over the weekend and try to determine if there is a pattern - engine cold,
or hot, AC on or not.

It's not likely the defroster was on. Unless by accident.

Other than this, I do love the car

Thanks,
Rogue Petunia

 

[Clive]

Hi,
Just drove my brand spanking new '05 Forester home today. When I parked,
before turning off the engine, I sat there just soaking it in. And I
noticed that when idling, the idle has a pattern in which it goes up, then
back down, then up, then back down. All by itself.

When idling I would think the idle should be steady. Any thoughts on this?
Yes, I will be calling the dealer, but am looking to hear if anyone else has
experienced this?

Thanks!
Rogue Petunia

A/C or electric cooling fan.
Normal.

 

[Edward Hayes]

I would give it several hundred miles before pestering the dealer. The
engine is very tight when new new and some run in time may change things as
it did on mine. ed

 

[td]

I had a rough idle problem on my new GT. it was a bad batch of oxygen
sensors. Once replaced, it idles perfectly smooth even with the AC and/or
defroster on. As you would expect of a modern car.

Tuan

 

[Henry Paul]

The idea is the A/C will cycle on and off and the A/C compressor will add
resistance to the engine lowering your rpms. The defroster also uses the A/C
intermittently to dehumidify the air.

Try with all of the environmental controls off and see if it persists.

 

[Rogue Petunia]

Thanks to all for your replies.
When I went to the car this morning I found that the AC button was on. So,
yeah the AC had been running when I noticed the fluctuating idle on Thursday
night.

And also, the more I think about it, I do recall several years back my '88
Subaru electric fan would kick on when parked after a long drive and the
engine was hot. It would make a similar loud noise and noticable drop in
rpms.

Thanks,
Rogue Petunia

 

[Niels]

What brands of gas are you using? I have found definite differences in the
way that 2004 Forester XT behaves. Gulf kills it, but loves Getty.

I keep very detailed gasoline consumption records, and approaching 20,000 mi
there are some definite winners & losers. Poor gas mileage generally
includes a rough idle & poor acceleration.