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07-05-2009, 06:06 PM | #1 |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
My car shakes at idle, vacuum goes to -25 at rev... leak??
Ok so this started happening lately...
My car shakes at idle, when the radiator fan turns on the car allmost dies. The vacuum at idle goes from -20 to -21 back and forth as it shakes When I rev my car while stopped, the gauge goes from -20 psi to 0 then down to -25... I have never had my car go down bellow -21 psi when reving it while stopped. What can my problem be? Thanks EDIT: Added logged numers and graphs at idle. (Scroll down it's in reply) VIDEO:
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Last edited by elitescouter; 07-06-2009 at 02:59 PM. Reason: Added logged numers and graphs at idle. (Scroll down it's in reply) |
07-05-2009, 07:12 PM | #2 |
Scooby Specialist
Member#: 147610
Join Date: Apr 2007
Chapter/Region:
Tri-State
Location: New Jersey
Vehicle:2007 Stage 2 STi WRB |
Can you still go into boost and besides the shaking does it still run fine? any weird sounds? Make sure your air filter isn't clogged up and check for an exhaust leak. I don't know if that could cause this but its not a bad idea to check anyway.
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07-05-2009, 07:17 PM | #3 |
Scooby Specialist
Member#: 209358
Join Date: Apr 2009
Chapter/Region:
Tri-State
Location: CNJ
Vehicle:06 Sti WRB |
probably vacuum leak. check all the hoses and hose going from "T" to boost gauge.
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07-05-2009, 07:23 PM | #4 |
Scooby Specialist
Member#: 136297
Join Date: Dec 2006
Chapter/Region:
NESIC
Vehicle:2015 S3 Gray |
my car idles around -23.5 vac runs fine and hits target boost. I dont think that its a vacuum leak.
looks like it may be something else wrong. "My car shakes at idle, when the radiator fan turns on the car allmost dies." This makes me question if its more of an electrical problem than a leak anywhere you car should not almost die if your radiator fan turns on. |
07-05-2009, 07:27 PM | #5 |
Scooby Specialist
Member#: 159796
Join Date: Sep 2007
Chapter/Region:
SCIC
Location: Los Angeles
Vehicle:2006 WRX |
start from the easy things first. check vacuum leak.
and im guessing you're not getting any CEL? |
07-06-2009, 01:43 AM | #6 |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
No CEL's or pending codes
I do hit my target boost. This all started happening after I used the flatfoot shifting that was put on my car. (It ran fine with it for a month or so and now this started happening) Reseting the ECU doesen't fix it. Maybe exhaust leak? Idk if this would cause it. |
07-06-2009, 04:19 AM | #7 |
Scooby Specialist
Member#: 92113
Join Date: Jul 2005
Chapter/Region:
MWSOC
Location: Belleville, IL
Vehicle:2019 WRX STi Limited World Rally Blue |
Check out cleaning the MAF sensor as well as the IVAC. My car didn't act exactly like this but I did have trouble ideling and car almost dieing anytime I pressed the clutch in. Both of them are easy to do and work for me.
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07-06-2009, 09:53 AM | #8 |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
Allready cleaned the MAF with CRC MAF sensor cleaner like 3 weeks ago, its still doing the same thing.
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07-06-2009, 09:59 AM | #9 |
Scooby Specialist
Member#: 172359
Join Date: Feb 2008
Chapter/Region:
MAIC
Location: virginia
Vehicle:2005 STi PSM |
TPS sensor maybe?
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07-06-2009, 11:10 AM | #10 |
Scooby Guru
Member#: 118209
Join Date: Jun 2006
Chapter/Region:
MWSOC
Location: North Dakota
Vehicle:2015 WRX Limitec |
Do you have a logging cable? i'm guessing you could probably post a log of your idle and it might help a little bit.
Also, vacuum isn't negative. Can't have negative psi. Vacuum is measured in inches of mercury, and always a positive number. |
07-06-2009, 11:10 AM | #11 |
Scooby Specialist
Member#: 187798
Join Date: Aug 2008
Chapter/Region:
MWSOC
Location: Elgin, IL
|
try raising your idle to 850 instead of 750.
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07-06-2009, 02:58 PM | #12 |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
Here is a log at idle, the spike = radiator fan turning on.
Here are the values at idle. If you see a problem =) let me know or if you need me to relog with another field that I have missed that's important. Thanks |
07-06-2009, 08:18 PM | #13 |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
Any ideas guys?
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07-06-2009, 11:46 PM | #14 |
Scooby Newbie
Member#: 211134
Join Date: May 2009
Chapter/Region:
SWIC
Location: AZ
Vehicle:2007 Impreza STi |
my engine is completely stock and my car sometimes shakes at idle too!
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07-07-2009, 12:22 AM | #15 |
Scooby Newbie
Member#: 215506
Join Date: Jun 2009
Chapter/Region:
South East
Location: NC & VA
Vehicle:05 FPRED 20PSI STI envy |
my car does it 80% of the time a start up. Then it smooths out, the ecu fixes the problem there is nothing to worry about.
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07-07-2009, 12:41 AM | #16 |
Scooby Newbie
Member#: 189014
Join Date: Sep 2008
Chapter/Region:
Tri-State
Location: Ownagetown Pa, 18249
Vehicle:2005 Impreza WRX World Rally Blue |
Do you have your A/C on?
Defiantly not a vacuum leak, they cause high idle. Line 47+48 = relevant correlation between engine load and RPM, means nothing to a diagnosis. This sounds like a ghost, unless your A/C is on or turning on when your radiator fan turns on or something. Has anything else happened recently that may be important like a large pothole or donuts or uncommon amount of miss-shifts? Erroneous idle/ misfire at idle can be associated with neutral position switch. I had this and a MIL(CEL) came on and by using a professional scanner I cleared the code and its gone. (probably not the same thing) How many drive cycles would you say you have gone through, it may take quite a few before a CEL comes on. |
07-07-2009, 02:09 AM | #17 | |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
Quote:
Not miss-shifts but i've been using the flat foot shifting that's been put on by a professional tuner with am opensource. I mean the car ran fine for a month or so with it. I did use the FFS allmost daily. I went through couple of drive cycles. Is there a way an exhaust leak can be causing this? EDIT: I forgot to mention, it shakes less when its cold, as soon as it warms up thats when it starts. |
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07-08-2009, 03:04 AM | #18 |
Scooby Newbie
Member#: 127164
Join Date: Sep 2006
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:05 WRX STi OBP |
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07-10-2009, 02:24 AM | #19 | |
Scooby Newbie
Member#: 189014
Join Date: Sep 2008
Chapter/Region:
Tri-State
Location: Ownagetown Pa, 18249
Vehicle:2005 Impreza WRX World Rally Blue |
Quote:
Can you look at live sensor data? That would show a bad TPS or anything else. Can you view or post Fuel Trim data? Can you run a 5 gas analyzer on it? What happens at a high idle like 2500rpm? Try some top engine cleaner and injector cleaner and see what happens... Still sounds like a ghost that you might just have to live with. |
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