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Old 07-26-2017, 11:24 AM   #1
NewtotheWRX
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Default 2017 WRX idling at 700rpm?

So today I noticed that my 2017 WRX was running a bit rough at idle and it runs at ~700rpm during idle.
Isn't this low? The idling can be a bit rough periodically and that 700rpm just seems low.

Anyone else have low rpm idling?
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Last edited by NewtotheWRX; 07-26-2017 at 11:30 AM.
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Old 07-26-2017, 11:34 AM   #2
sc00ter
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700rpm idle is perfectly normal. Rough idle might not be, though. Are you tuned? What fuel is in the tank?
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Old 07-26-2017, 11:40 AM   #3
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Quote:
Originally Posted by sc00ter View Post
700rpm idle is perfectly normal. Rough idle might not be, though. Are you tuned? What fuel is in the tank?
No tune and only been using 91 Octane.
I suppose "rough" needs further clarification:
Periodically my idle has the car kinda shaking a bit, not a lot and it's kinda light, but there is some. Sometimes there is no shaking.

I just got in my car again to test it and it was pretty smooth. But after driving a bit sometimes it's rough.
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Old 07-26-2017, 11:57 AM   #4
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Quote:
Originally Posted by NewtotheWRX View Post
No tune and only been using 91 Octane.

I suppose "rough" needs further clarification:

Periodically my idle has the car kinda shaking a bit, not a lot and it's kinda light, but there is some. Sometimes there is no shaking.



I just got in my car again to test it and it was pretty smooth. But after driving a bit sometimes it's rough.


Well, now "shaking" needs further clarification.
Are we talking more of a vibration that coincides w/ a quick (for half a second or less) drop of like 50- 100 rpm?

If that's what is happening it's totally normal, it's one of the characteristics of direct injected engines and nothing is wrong. Every 15+ WRX does it and AFAIK there is nothing you can do to change that.
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Old 07-26-2017, 12:02 PM   #5
NewtotheWRX
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Quote:
Originally Posted by Undercut56 View Post
Well, now "shaking" needs further clarification.
Are we talking more of a vibration that coincides w/ a quick (for half a second or less) drop of like 50- 100 rpm?

If that's what is happening it's totally normal, it's one of the characteristics of direct injected engines and nothing is wrong. Every 15+ WRX does it and AFAIK there is nothing you can do to change that.
I guess the best I could describe the shaking is more like a... burbling where the car doesn't idle entirely smoothly but I can feel the engine doing whatever it's doing. It's not some intense shaking by any means, but enough that I notice the difference to when it idles smoothly.

I shall have to pay attention to see whether the vibration coincides with slight rpm dips, thanks for the info.

I've read in a couple other threads where slight vibration it seems normal, but since it's all through written description it's hard to get an exact sense of what normal is.
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Old 07-26-2017, 12:06 PM   #6
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first boxer engine?
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Old 07-26-2017, 12:09 PM   #7
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Quote:
Originally Posted by mishapopa View Post
first boxer engine?
Yes, the first I've ever had real experience with at least.
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Old 07-26-2017, 12:17 PM   #8
whiplash willy
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Since this is your first Boxer engine, and the RPMs aren't dropping noticeably with the roughness, it is likely just a normal characteristic of a 4 Cyl Boxer engine called "Rocking Couple"

Quote:
The boxer configuration is the only configuration in common use that does not have unbalanced forces with a four-stroke cycle regardless of the number of cylinders, as long as both banks have the same number of cylinders.

These engines do not require a balance shaft[4] or counterweights on the crankshaft to balance the weight of the reciprocating parts, which are required in most other engine configurations. However, in the case of boxer engines with fewer than six cylinders, unbalanced moments (a reciprocating torque also known as a "rocking couple") are unavoidable due to the "opposite" cylinders being slightly out of line with each other.[3]

Other engine configurations with natural dynamic balance include the straight-six, the straight-eight, the V12, and the V16.
Boxer engines (and flat engines in general) tend to be noisier than other common engines for both intrinsic and other reasons.[5] In cars, valve clatter from the engine compartment is not damped by air filters or other components.[6]
Here is a great video for those not familiar with Boxer engines:

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Old 07-26-2017, 12:44 PM   #9
NewtotheWRX
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Quote:
Originally Posted by whiplash willy View Post
Since this is your first Boxer engine, and the RPMs aren't dropping noticeably with the roughness, it is likely just a normal characteristic of a 4 Cyl Boxer engine called "Rocking Couple"



Here is a great video for those not familiar with Boxer engines:

https://youtu.be/VL69r96VfuU

Awesome, thanks for that info and link.
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Old 07-26-2017, 07:55 PM   #10
Dulath
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700 RPM is the target idle for FA20DIT when the car is warm and you are in neutral. Put it in gear (keep clutch pedal down) and it should idle up to 800 RPM. You can set the idle speed with an access port.
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Old 07-26-2017, 08:33 PM   #11
NewtotheWRX
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Quote:
Originally Posted by Dulath View Post
700 RPM is the target idle for FA20DIT when the car is warm and you are in neutral. Put it in gear (keep clutch pedal down) and it should idle up to 800 RPM. You can set the idle speed with an access port.
Thanks, that's good to know my rpm is right on the dime then. I'm still iffy about the access port due to warranty concerns I admit.

I like the Engineering Explained videos, clear and concise explanation of that boxer engine. I also like the idea of horizontal pistons hammer towards each other.

Also glad to know that the reciprocating torque thing in terms of my idling.

Although I am still curious why it happens only periodically during idling.
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Old 07-26-2017, 11:49 PM   #12
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Quote:
Originally Posted by NewtotheWRX View Post

Although I am still curious why it happens only periodically during idling.
Is your A/C compressor kicking on/off? This puts load on the engine.
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Old 07-27-2017, 11:19 AM   #13
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Quote:
Originally Posted by pw- View Post
Is your A/C compressor kicking on/off? This puts load on the engine.
I actually rarely use the AC and the rough idling periodically occurs regardless.
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