Welcome to the North American Subaru Impreza Owners Club Sunday December 21, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 04-19-2009, 12:21 AM   #1
impre25ive
Scooby Newbie
 
Member#: 198933
Join Date: Jan 2009
Default '09 2.5i Rev's staying high?

Anyone else notice, that the revs pause for a little. When rev'ed the engine revs stay up for a little bit, then come back down.

Its not like most where the tack goes up, then right back down.

Anyone know why? or how to fix this "problem".
* Registered users of the site do not see these ads.
impre25ive is offline   Reply With Quote
Old 04-19-2009, 03:18 AM   #2
jeonster
Scooby Newbie
 
Member#: 198854
Join Date: Dec 2008
Chapter/Region: NESIC
Location: Hartford, CT
Vehicle:
2013 WRX
Silver

Default

i'll try it out tomorrow.
jeonster is offline   Reply With Quote
Old 04-19-2009, 03:50 AM   #3
Tomato_88
Scooby Newbie
 
Member#: 204277
Join Date: Feb 2009
Location: Central California
Vehicle:
2008 Impreza 2.5i
Dark Gray Metallic

Default

I have an 08 that does the same thing. I notice in everyday driving, shifting between gears mostly. I have no clue why it does it, or if it is supposed to.
Tomato_88 is offline   Reply With Quote
Old 04-19-2009, 11:15 AM   #4
rpthack
Scooby Newbie
 
Member#: 207650
Join Date: Apr 2009
Location: SC
Vehicle:
'09 2.5i

Default

I'd guess what you're experiencing is our heavy flywheel; the greater mass makes momentum changes slow. Just like a light racing flywheel revs up quickly and slows down just as quickly, a heavy flywheel revs up slowly and slows down just as slowly. Someone who's cracked a science book in the last decade can probably give you the ins and outs of it.
rpthack is offline   Reply With Quote
Old 04-19-2009, 11:30 AM   #5
Un0RiGiNaL
Scooby Specialist
 
Member#: 189748
Join Date: Sep 2008
Chapter/Region: MAIC
Default

is your car auto?
Un0RiGiNaL is offline   Reply With Quote
Old 04-19-2009, 03:39 PM   #6
impre25ive
Scooby Newbie
 
Member#: 198933
Join Date: Jan 2009
Default

Quote:
Originally Posted by Un0RiGiNaL View Post
is your car auto?
no its a 5 speed.

anyone who has a '08/'09 2.5i, just try putting in the clutch and revving it. youll notice the revs stay up a little bit before coming back down.

perhaps what the poster a couple up said, about it being the flywheel.
impre25ive is offline   Reply With Quote
Old 04-19-2009, 03:41 PM   #7
blernin41
Scooby Specialist
 
Member#: 200321
Join Date: Jan 2009
Chapter/Region: South East
Location: Arkansas
Vehicle:
2009 Forester 2.5XP
Armpit Green

Default

.....get a lightweight flywheel or pulley.
blernin41 is offline   Reply With Quote
Old 04-19-2009, 03:45 PM   #8
scoobyviking
Scooby Newbie
 
Member#: 192241
Join Date: Oct 2008
Chapter/Region: RMIC
Location: Colorado
Vehicle:
2013 STi
Plasma Blue Pearl

Default

i am fairly sure that it happens with most if not all newer subarus. it is something with the way they are tuned. the ecu keeps the revs high for s short while and then they settle down to normal idle. i don't know exactly the reason and i have quite a few posts about it before and it also happens with mine. if you let the clutch out it should go back down immediately. sorry i don't have the technical reason for this, and it's totally normal. hope that helps.

kb
scoobyviking is offline   Reply With Quote
Old 04-19-2009, 03:47 PM   #9
Zac86
Scooby Newbie
 
Member#: 136919
Join Date: Jan 2007
Chapter/Region: W. Canada
Location: North Pole
Vehicle:
2005 Legacy GT Wagon
ABP

Default

Ussualy has to do with the DBW.
Zac86 is offline   Reply With Quote
Old 04-19-2009, 04:45 PM   #10
SubiFTW
Scooby Specialist
 
Member#: 138728
Join Date: Jan 2007
Chapter/Region: W. Canada
Location: Winnipeg,MB
Vehicle:
MY06 2.5i Impreza
Aspen White

Default

Happens on my 06
SubiFTW is offline   Reply With Quote
Old 04-19-2009, 05:53 PM   #11
Nacron
Scooby Newbie
 
Member#: 187115
Join Date: Aug 2008
Chapter/Region: HIIC
Location: Waipahu, HI
Vehicle:
2010 Legacy 2.5i
Steel Silver Metalic

Default

Noticed this once on my automatic. mashed the pedal to get around this guy and he sped up so I let off and it hung for a while before dropping.
Nacron is offline   Reply With Quote
Old 04-19-2009, 06:19 PM   #12
Jerry Xu
Scooby Specialist
 
Member#: 36629
Join Date: May 2003
Location: Baltimore Maryland
Vehicle:
07 2.5i
Regularly Being Modified

Default

It is in the program of their DBW system.
Basically everything is a delay (I hate it so much).
You step on gas, rpm stays low for a second; then you take you foot off, the rev stays hi for a second, etc. Drives me crazy for a few months.
Jerry Xu is offline   Reply With Quote
Old 04-19-2009, 07:22 PM   #13
aurtini
Scooby Newbie
 
Member#: 205655
Join Date: Mar 2009
Chapter/Region: RMIC
Location: Salt Lake City, UT
Vehicle:
2006 Impreza 2.5i
Black

Default

I always attributed this to the rotational momentum from the engine components (flywheel, etc) on my 06. The annoying rev thing that I've noticed is when you roll up to a stop with the car still in gear with the clutch in the ECU will keep the engine speed above idle by a few hundred RPM until I either let the clutch out or put the shifter into neutral.
aurtini is offline   Reply With Quote
Old 04-19-2009, 08:55 PM   #14
Jerry Xu
Scooby Specialist
 
Member#: 36629
Join Date: May 2003
Location: Baltimore Maryland
Vehicle:
07 2.5i
Regularly Being Modified

Default

Reducing mass and SRI intake help but that is not the root cause of the problem. I was able to cut 50-70% of the delay with SRI and LWCP. Next planned is the flywheel. But the DBW I am unable to touch even with open source tuning. So we shall expect some residual lag.
Jerry Xu is offline   Reply With Quote
Old 04-19-2009, 10:15 PM   #15
GEE-OTTO
Scooby Specialist
 
Member#: 201277
Join Date: Jan 2009
Chapter/Region: MAIC
Location: Arlington VA
Vehicle:
2009 Legacy GT
OBP

Default

Your problem has nothing to do with mass or momentum or any of the bs replied there is a flaw in the ECU btwn the DBW unit reference tables and the ECU itself. This issue is imply fixed with a SOA reflash to your car it corrects several issues associated with the way the car operates I had this issue with my 2008 LEgacy took it to the dealer they hooked it up to the diagnostic system and reflashed it took about 45 mins. This was the most annoying issue with my whenever I pushed in the clutch it would idle to 3k rpms then drop to 500. After the reflash it is a DREAM to drive it runs not as lean as it did from the factory it feels like a lil more pep in its step and the erratic idle is solved. Take it to the dealer ask to have the erratic idle issue looked at and they should fix it. If youre not under warranty it is only $94
GEE-OTTO is offline   Reply With Quote
Old 04-19-2009, 10:56 PM   #16
ohm
Scooby Specialist
 
Member#: 178468
Join Date: Apr 2008
Location: Somerset, NJ
Vehicle:
2007 UGM STI
IAG Built

Default

The same thing actually happens on my 07 STI. No matter all the different ways I have tried to shift in order to combat this, the issue still exists. I wouldn't say I have gotten used to it, but it has become something I deal with.
ohm is offline   Reply With Quote
Old 04-19-2009, 10:56 PM   #17
Jerry Xu
Scooby Specialist
 
Member#: 36629
Join Date: May 2003
Location: Baltimore Maryland
Vehicle:
07 2.5i
Regularly Being Modified

Default

Gee-Otto,
you had a different problem looks like.
OP's problem is universal, staring from 05 on I think. Don't believe subaru has a solution yet.
Jerry Xu is offline   Reply With Quote
Old 04-20-2009, 04:42 PM   #18
keyserblade
Scooby Newbie
 
Member#: 209175
Join Date: Apr 2009
Vehicle:
2008 Impreza 2.5 man

Default

Does anyone know if the flash Gee-Otto is talking about works for 08 Imprezza's? I had my car in complaining about this issue shortly after getting the car and the dealer told me that everything was normal. If Subaru doesn't fix this issue there are going to be alot of blown syncros. The shift from 1st gear to 2nd gear is brutal! I'm sure there alot of drivers out there shifting like a normal car. I had a Contour SVT in the past that the RPM's would fall slowly after letting of the gas. They claimed it was for emissions. On that car you could put a restriction in a pipe that fed air into the throttle body and it would reduce the "throttle lag." With the Subaru running drive by wire I'm sure they are just holding the throttle plate open for a second after the drive releases the gas pedal. Are there any after market reprograms for the NA cars to fix this yet?
keyserblade is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Exhaust for '09 2.5i 5 door stackplates Normally Aspirated Powertrain 39 12-09-2013 05:21 PM
'09 2.5i asking: How's your aftermarket intake? epistax Normally Aspirated Powertrain 7 12-03-2009 05:15 PM
'09 Legacy 2.5i Suspension ms jdm Brakes, Steering & Suspension 1 11-17-2008 01:13 PM
'09 Impreza 2.5i w/NAV only with automatic rsholland News & Rumors 13 09-09-2008 03:54 PM
Looking at an '09 Legacy 2.5i Saleen501 Newbies & FAQs 1 06-29-2008 06:20 PM


All times are GMT -4. The time now is 08:15 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.