Welcome to the North American Subaru Impreza Owners Club Friday August 1, 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 > Factory 2.0L Turbo 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 02-29-2012, 12:39 PM   #1
quazimoto
Scooby Guru
 
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va
Default If You Have A Misfire Code Please Read This!

5-10x a week an individual posts about having a misfire issue (MAINLY BECAUSE OF THE INABILITY TO USE THE SEARCH FEATURE!!!). This is a very common problem and there are alot of threads addressing this very problem. So here are the possible issues and solutions (read this first,then post about an issue if you have no resolution after trying said solutions):


MISFIRES


1. Wrong, worn or incorrectly gapped spark plugs. Generally NGK work best gapped between .028"-.030".

2. Clogged/dirty/bad injectors or fuel filter. Try changing the fuel filter. The maintenance schedule for the filter is every 30K miles. Have the injectors professional cleaned or at least run several bottles of a good injector cleaner through the gas tank. Also make sure you are using the correct octane gas! Either 91 or 93 unless you are specifically tuned for another octane!! (IE: race gas or E85) You can swap injectors from another cylinder and see if the misfire follows. If so this would indicate an injector issue if it does move..

3. Check valve clearances & compression. Leak down/compression test.

4. Dirty MAF sensor. This causes an incorrect airflow readings. Misfires can result. Clean with CRC MAF cleaner or NON chlorinated brake cleaner. Make sure you are actually cleaning the MAF sensor and not just the IAT sensor. Common mistake.

5. Vacuum leaks or preturbo leak. Check where the FPR hose connects (generally you could get a P0457 or P0171 with this as well). Check the turbo inlet pipe where it connects to the turbo. This pipe is famous for ripping and causing a huge preturbo leak (P0171 as well).

6.Poor grounds/grounding. Clean the battery ground cable and ones that run to the intake manifold. Make sure all are connected. These are sensor grounds and must be kept clean.

7. Cam timing. Check cam timing per the service manual. Clean cam and crank sensor face.

8. Excessive PCV blow by. PVC gases will effectively lower the octane content of gasoline/petrol and can cause misfires along with knock. Get a catch can or air/oil seperater.

9. Carbon build up in heads/cylinders. You can use Seafoam or top end cleaner as well as other type of carbon remover.

10. Lightweight flywheels or crank pulleys. (phantom misfires) Can cause false misfires. Opensource tuning can disable.

11. Bad/loose coil pack or coil pack connector
. Test coil pack and move to other cylinder to see if DTC changes. If so this would indicate a coil pack issue. Also check the tower boot for corrosion.

12. Faulty fuel pressure regulator or fuel pump. Check fuel pressure. It should be bewteen 35-38psi idle @ sealevel. Removing the vac line at idle should give you 43 psi. The FPR is a 1:1 rising rate. For every 1 psi manifold positive pressure the fuel pressure should rise 1 psi.

13. Faulty front O2 sensor
Replace with new


14. Damaged crank timing gear

15. Misfires all cyclinders: Coil pack connectors mixed up (correct way:black to back,white to front),light weight flywheel,bad/unplugged crank or cam sensor,incorrect gapped plugs,cam timing off.

FYI-The bugeyes were plauged with misfires. Updating the ROM in the ECU to the latest revision from Subaru helps alleviate most false misfire issues. This can be done through the stealership or opensource software.

Hope this helps! Will add as other causes are found.
* Registered users of the site do not see these ads.

Last edited by quazimoto; 06-06-2014 at 08:28 AM.
quazimoto is offline   Reply With Quote
Old 02-29-2012, 12:51 PM   #2
WhiteBgeye02
Scooby Specialist
 
Member#: 224785
Join Date: Sep 2009
Chapter/Region: MWSOC
Location: neenah
Vehicle:
2005 wrx-jdm207
i went black...

Default

this deserves a sticky! i am sick off ppl posting about misfires. if you check all this and still cant figure it out it may be time for the professionals to figure it out.
WhiteBgeye02 is offline   Reply With Quote
Old 02-29-2012, 01:41 PM   #3
2gnt2wrx
Scooby Specialist
 
Member#: 123625
Join Date: Aug 2006
Chapter/Region: MWSOC
Location: Waukesha, WI
Vehicle:
2002 wrx
wrb stg2

Default

You can move injectors the same way you explained the coil pack procedure to see if the misfire follows.

I have in the past slightly..."I MEAN SLIGHTLY" twisted the prongs to the coil packs and re-installed to ensure contact is being made inside the connectors.
2gnt2wrx is offline   Reply With Quote
Old 02-29-2012, 01:53 PM   #4
BlueWagon02
Scooby Newbie
 
Member#: 207315
Join Date: Apr 2009
Chapter/Region: TXIC
Location: Houston, TX
Vehicle:
2002 WRX Wagon
World Rally Blue

Default

I have seen the same or similar post at clubwrx.net, and an additional post may be helpful for issues that could cause a misfire on all cylinders, not just one or two.
BlueWagon02 is offline   Reply With Quote
Old 02-29-2012, 01:57 PM   #5
quazimoto
Scooby Guru
 
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va
Default

Quote:
Originally Posted by 2gnt2wrx View Post
You can move injectors the same way you explained the coil pack procedure to see if the misfire follows.

I have in the past slightly..."I MEAN SLIGHTLY" twisted the prongs to the coil packs and re-installed to ensure contact is being made inside the connectors.
Updated! Yeah forgot to put that in there.
quazimoto is offline   Reply With Quote
Old 02-29-2012, 02:00 PM   #6
gsmith304
Scooby Newbie
 
Member#: 302159
Join Date: Nov 2011
Chapter/Region: MAIC
Location: West Virginia
Vehicle:
2003 WRX
Sonic Yellow

Default

Awesome list. Saves some $$$$ by doing these simple tests for sure
gsmith304 is offline   Reply With Quote
Old 03-01-2012, 09:21 AM   #7
quazimoto
Scooby Guru
 
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va
Default

Quote:
Originally Posted by BlueWagon02 View Post
I have seen the same or similar post at clubwrx.net, and an additional post may be helpful for issues that could cause a misfire on all cylinders, not just one or two.
Yeah,I made that thread as well . Good idea about the multiple misfires.
quazimoto is offline   Reply With Quote
Old 03-01-2012, 09:47 AM   #8
WhiteBgeye02
Scooby Specialist
 
Member#: 224785
Join Date: Sep 2009
Chapter/Region: MWSOC
Location: neenah
Vehicle:
2005 wrx-jdm207
i went black...

Default

i also believe there is a new rom you can flash onto your car to fix misfire problems. would have to check around romraider forums though.
WhiteBgeye02 is offline   Reply With Quote
Old 03-01-2012, 01:43 PM   #9
2gnt2wrx
Scooby Specialist
 
Member#: 123625
Join Date: Aug 2006
Chapter/Region: MWSOC
Location: Waukesha, WI
Vehicle:
2002 wrx
wrb stg2

Default

Quote:
Originally Posted by WhiteBgeye02 View Post
i also believe there is a new rom you can flash onto your car to fix misfire problems. would have to check around romraider forums though.
You can turn off the roughness monitors for each cylinder "If you know it's false". While not advisable, you will be able to tell if your car is really misfiring.
2gnt2wrx is offline   Reply With Quote
Old 03-01-2012, 02:32 PM   #10
jerbull88
Scooby Newbie
 
Member#: 248089
Join Date: May 2010
Location: albany, ga
Vehicle:
2011 wrx premium
metallic grey

Default

Include links for how to's and this should be a sticky for sure.
jerbull88 is offline   Reply With Quote
Old 03-01-2012, 04:07 PM   #11
quazimoto
Scooby Guru
 
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va
Default

Quote:
Originally Posted by WhiteBgeye02 View Post
i also believe there is a new rom you can flash onto your car to fix misfire problems. would have to check around romraider forums though.
It's any ROM.

quazimoto is offline   Reply With Quote
Old 04-01-2012, 02:21 PM   #12
ddaddyo
Scooby Newbie
 
Member#: 226894
Join Date: Oct 2009
Location: Kalispell, MT
Vehicle:
2006 WRX STI
CGM

Default

Cleaning the evap purge valve solved my misfire on cylinder #1 issue. It must have been getting stuck open or it was in backwards. Arrow for "to e/g" should point to the left (toward air intake).
ddaddyo is offline   Reply With Quote
Old 04-01-2012, 05:26 PM   #13
TwoFifty
Scooby Newbie
 
Member#: 261764
Join Date: Oct 2010
Location: Kelowna BC
Vehicle:
2003 Impreza WRX
Blue

Default

Quote:
Originally Posted by quazimoto View Post
4. Dirty MAF sensor. This causes an incorrect airflow readings. Misfires can result. Clean with CRC MAF cleaner or NON chlorinated brake cleaner. Make sure you are actually cleaning the MAF sensor and not just the IAT sensor. Common mistake.

Don't Subaru use a hot wire style MAF sensor instead of an IAT? (on 02+ atleast) Or do you mean MAP?
TwoFifty is offline   Reply With Quote
Old 04-01-2012, 06:10 PM   #14
2gnt2wrx
Scooby Specialist
 
Member#: 123625
Join Date: Aug 2006
Chapter/Region: MWSOC
Location: Waukesha, WI
Vehicle:
2002 wrx
wrb stg2

Default

The iat is in the same housing as the maf. Only when you first look at it, the iat sensor is the one that is easily visible. Where the maf is up inside the plastic tube/housing, barely visible.
2gnt2wrx is offline   Reply With Quote
Old 04-01-2012, 07:39 PM   #15
quazimoto
Scooby Guru
 
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va
Default

Quote:
Originally Posted by TwoFifty View Post
Don't Subaru use a hot wire style MAF sensor instead of an IAT? (on 02+ atleast) Or do you mean MAP?
I mean exactly what I said....... Have you not bothered looked at your MAF sensor? I have. There are several tutorials on here on how to clean the MAF sensor on a Subaru. Picture of a Subaru MAF sensor for reference............you tell me The amber bulb is the IAT sensor

Last edited by quazimoto; 04-14-2012 at 07:50 AM.
quazimoto is offline   Reply With Quote
Old 04-01-2012, 08:11 PM   #16
TwoFifty
Scooby Newbie
 
Member#: 261764
Join Date: Oct 2010
Location: Kelowna BC
Vehicle:
2003 Impreza WRX
Blue

Default

Quote:
Originally Posted by quazimoto View Post
I mean exactly what I said....... Have you not bothered looked at your MAF sensor? I have. There are several tutorials on here on how to clean the MAF sensor on a Subaru. Picture of a Subaru MAF sensor for reference............you tell me
Yes i am well aware of what my MAF looks like

I do however see where people go wrong now though, i'd never really thought of it like that before as i'd just always referred to the whole thing as the MAF, that's why i was getting confused

Last edited by TwoFifty; 04-01-2012 at 08:21 PM.
TwoFifty is offline   Reply With Quote
Old 04-01-2012, 08:46 PM   #17
bryan.paradise
Scooby Newbie
 
Member#: 308893
Join Date: Feb 2012
Chapter/Region: Tri-State
Location: Lancaster, PA
Vehicle:
2002 WRX Wagon
Aspen White

Default

Yeah well unfortunately, the "professionals" at the Subaru dealership near me want to charge an arm and a leg to troubleshoot and not take responsibility when they don't fix a problem. Ridiculous.
bryan.paradise is offline   Reply With Quote
Old 04-01-2012, 09:28 PM   #18
hoffmanEstates
Scooby Guru
 
Member#: 122043
Join Date: Aug 2006
Chapter/Region: MWSOC
Location: aurora
Vehicle:
04 wagonier
psm

Default

I was chasing a miss fire for ever.... I changed my plugs and coil packs and runs vibration free
hoffmanEstates is offline   Reply With Quote
Old 05-01-2012, 07:33 PM   #19
wrxguy04
Scooby Specialist
 
Member#: 261086
Join Date: Oct 2010
Chapter/Region: South East
Location: Mebane, NC
Vehicle:
2004 Impreza WRX
Platinum Silver Metallic

Default

All but number 3&10.

Why i didnt check for 3; the heads i have currently are in good condition and i have them built with oem valves, buckets, springs and retainers.

Why i didnt check for 10; i have the 4eat auto trans and all pulleys are brand new OEM.

What about PCV Blowby?
wrxguy04 is offline   Reply With Quote
Old 05-23-2012, 05:01 PM   #20
shwagondawheels
Scooby Newbie
 
Member#: 320974
Join Date: May 2012
Default

could a bad MAP sensor cause a buck or misfire?
shwagondawheels is offline   Reply With Quote
Old 05-23-2012, 07:07 PM   #21
quazimoto
Scooby Guru
 
Member#: 70395
Join Date: Sep 2004
Chapter/Region: MAIC
Location: Da-boonies,Va
Default

Not that I know of. The ECU only uses the MAP sensor to reference boost pressure unless the MAF fails. Then the ECU will switch into a "fail safe" speed density mode.
quazimoto is offline   Reply With Quote
Old 05-23-2012, 07:39 PM   #22
Uncle Scotty
Scooby Guru
 
Member#: 16200
Join Date: Mar 2002
Vehicle:
OK Houston
we have an Uncle

Default

Quote:
Originally Posted by shwagondawheels View Post
could a bad MAP sensor cause a buck or misfire?
you would get a CEL for that

is the CEL on??

what codes??
Uncle Scotty is offline   Reply With Quote
Old 05-23-2012, 10:06 PM   #23
shwagondawheels
Scooby Newbie
 
Member#: 320974
Join Date: May 2012
Default

Quote:
Originally Posted by quazimoto View Post
Not that I know of. The ECU only uses the MAP sensor to reference boost pressure unless the MAF fails. Then the ECU will switch into a "fail safe" speed density mode.
ok so the MAP sensor in dedicated to the boost map only?

the other cars i,ve had misfire or buck from a bad MAP sensor where MAFlless cars (obviously speed density w/ maybe alpha n blend map on a n/a car) reason for my thought

it's the misfire/buck in the other thread(s) lol
shwagondawheels is offline   Reply With Quote
Old 05-23-2012, 10:10 PM   #24
shwagondawheels
Scooby Newbie
 
Member#: 320974
Join Date: May 2012
Default

Quote:
Originally Posted by Uncle Scotty View Post
you would get a CEL for that

is the CEL on??

what codes??
random multiple
shwagondawheels is offline   Reply With Quote
Old 05-23-2012, 10:12 PM   #25
nismopowerdqg
Scooby Specialist
 
Member#: 312580
Join Date: Mar 2012
Chapter/Region: MAIC
Location: Richmond, VA
Vehicle:
2010 WRX SWP@310/334
Cobb/Torqued Performance

Default

Uncle scotty, the codes my car is throwing are p0301 p0302 p0303 p0304
nismopowerdqg 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
If you have spare change then please donate via Text-to-Donate. Thank You!!! soccrstar Off-Topic 16 01-16-2010 01:33 AM
If you have a radar detector please read silversubie02WRX North West Impreza Club Forum -- NWIC 42 06-02-2008 05:56 PM
If you have a PDE downpipe please read cwb124 Factory 2.0L Turbo Powertrain 1 09-26-2002 03:17 PM
('93-'01) if YOU tinted your OWN windows, please read. Pipercub Impreza Forum 1 04-27-2001 09:33 PM


All times are GMT -4. The time now is 01:23 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.