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Old 03-11-2005, 11:19 AM   #1
RodimusPrime
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Default new 2005 RS - question on a slight rough idle?

Hi all,

I have a 2005 RS (5spd) with about 400 miles on it. I notice that once the car warms up, when I am at a stop sitting in neutral, I can feel a barely perceptable roughness in the idle. It sits around 500 rpm or so and the needle doesn't move on the tachometer, but I can feel just the slighest little shakiness in my seat, and it's not like a completely regular thing. Seems like every few seconds, but not on a normal repeating patern.

Again, this is REALLY a slight little thing - not a huge shake at all. Am I just being paranoid or should I take this in to get looked at?

Thanks
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Old 03-11-2005, 11:25 AM   #2
Aphex28
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Normal.. have you ever had a car with a horizontally imposed engine before?

It moves so much because instead of moving up and down the pistons move back and forth.
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Old 03-11-2005, 11:30 AM   #3
Airboy
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Quote:
Originally Posted by RodimusPrime
Hi all,

I have a 2005 RS (5spd) with about 400 miles on it. I notice that once the car warms up, when I am at a stop sitting in neutral, I can feel a barely perceptable roughness in the idle. It sits around 500 rpm or so and the needle doesn't move on the tachometer, but I can feel just the slighest little shakiness in my seat, and it's not like a completely regular thing. Seems like every few seconds, but not on a normal repeating patern.

Again, this is REALLY a slight little thing - not a huge shake at all. Am I just being paranoid or should I take this in to get looked at?

Thanks
I am pretty sure that your car is idling at ~750rpm, the normal value. One "tick" below the 1k mark is 750, two is 500...the tach is kind of confusing this way.

The "shake" that happens every few seconds would seem to be "normal" as mine ('05 RS) does the same thing.
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Old 03-11-2005, 12:02 PM   #4
RodimusPrime
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You're probably right about the 750 - i'll check it out next time i'm in the car.

Aphex - this is my first boxer engine, and first subaru! So no, i've never experienced that, but it makes sense.

Thanks for the info guys! My mind is now at ease
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Old 03-11-2005, 12:53 PM   #5
Aphex28
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Quote:
Originally Posted by RodimusPrime
Aphex - this is my first boxer engine, and first subaru! So no, i've never experienced that, but it makes sense.
Ah well then congratumalations! Because of the different layout of the engine it has some noises you may not be used to, ticking and vibrations
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Old 03-11-2005, 08:13 PM   #6
wht052.5
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Yup, welcome to the boxer club. These idiosyncrasies are what make the Subie's so unique. Off idle, though you won't find a smoother motor.
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Old 03-11-2005, 11:25 PM   #7
Caplin 2.5
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haha everybody has this so called "problem". Its just normal get used to it. the only time you have to worry is when it shuts off.
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Old 03-11-2005, 11:40 PM   #8
RodimusPrime
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^^ haha ok well that's good to know! Thanks for the welcome guys - I just put up a little post in the newbie section with some pictures of the new ride:

http://forums.nasioc.com/forums/showthread.php?t=732179
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Old 03-14-2005, 02:25 PM   #9
garface
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I thought the H4 was supposed to be smoother and more balanced due to its design. Mine is very smooth at idle with the STi EJ20.
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Old 03-14-2005, 02:43 PM   #10
bobby d
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I had a hard time getting used to my 05 RS at first. I went from a quiet little 2001 Civic EX to this growling machine. LOL I like it though, I almost have 3,000 miles on the car and I am used to all the weird noises and the idle problem I had seemed to stop. I think the computer was just getting used to things.
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Old 03-14-2005, 03:55 PM   #11
powerlabs
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Quote:
Originally Posted by wht052.5
Yup, welcome to the boxer club. These idiosyncrasies are what make the Subie's so unique. Off idle, though you won't find a smoother motor.

Have you been driving a tractor before you got your subi Boxers are nice motors, but smooth? Erm, try V-8 / V-10 / V12... A V6 and many inline 4s are smoother also. The whole point of a boxer is good low end torque and low center of gravity; they are/were never designed to be very smooth, and definitely aren't with only 2 cylinders in each side of the car.
Also, the engine is supposed to idle at 700RPM. Mine stays between 692RPM and 720RPM when warm, usually hovering around 700 - 707 (monitored digitally via S-AFC rpm pickup). If your idle drops below 650 the car will shake. A rough idle is usually a sign of a vacuum leak.
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Old 03-24-2005, 03:36 PM   #12
wht052.5
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This is old but, H4's have no balance issues/shafts. other than a rotary there is no other perfectly balanced, and yes, smooth motors that don't have to have some sort of correction.

As for the tractor thing, I have driven old BMW's, Hondas,VW's, Land rovers,
Subies (of course). No john Deere's.
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Old 03-24-2005, 04:22 PM   #13
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Ok.. gotta jump in here...
Boxer engines, along with Inline 6cyls and V12s are naturally balanced motors. Very smooth! I found a great article a long time ago that goes into a fair bit of detail about what motors are balanced and such. I liked it enough, I scraped it from the site, and put it on my server. Her is the link.

http://www.aphkac.com/automotive/tec...ce/smooth1.htm
And specifically, for the Boxer engine.
http://www.aphkac.com/automotive/tec...ce/smooth5.htm

The rough idle issue some (including myself) notice, could be a result of rotational mass. The flywheel holds energy, and if its RPM changes, even just a little bit, you'll feel it in your car. Kinda like when you blip the gas, the car shakes.

Just my .02c worth.
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Old 03-24-2005, 04:51 PM   #14
greg donovan
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when the ac cycles on and off there is always a bit of a "burble" in the idle.
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Old 03-24-2005, 04:56 PM   #15
wht052.5
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[quote=Skidd]Ok.. gotta jump in here...
Boxer engines, along with Inline 6cyls and V12s are naturally balanced


Thank you.
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