Welcome to the North American Subaru Impreza Owners Club Wednesday August 20, 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 03-27-2009, 12:55 PM   #1
formula91
Scooby Specialist
 
Member#: 102984
Join Date: Dec 2005
Chapter/Region: MWSOC
Location: Northbrook, IL
Vehicle:
2005 2.5RS 4EAT
Platinum Silver

Default Romraider loggers: help me out diagnosing a O2 problem.

So I have a reoccuring issue with a P0131 CEL, but I'm not sure if the O2 sensor is really what the problem is.

Before you tell me about the regular stuff. Yes, I have connected all my vacuum hoses, cleaned the MAF, tried injector cleaner. I went through all my vacuum hoses in fact, and there aren't any leaks to my knowledge. There is NO unmetered air coming in. If there a pinhole leak or something, that wouldn't have been enough to shoot a CEL like this.

The only mod that changes A/F ratio for me is a hybrid intake.
Time-----AFL-----Nbo2AF--Engine Load%
59359----9.9-----14.13----18.04
59500----9.9-----14.59----17.65
59625----9.9-----14.7-----18.04
59750----9.9-----14.47----9.8
59890----9.53----13.44----8.63
60015----9.18----12.4-----7.06
60140----8.85----11.48----7.45
60265----8.54----11.83----7.45
60390----8.25----12.75----7.06
60515----7.98----13.9----7.06
60656----7.72----15.5----7.06
60781----7.49----18.26----7.06
60906----7.45----20.33----9.41
61031----7.6-----20.33----10.98
61156----7.74----20.33----11.76
61296----7.87----18.6-----11.37
61421----9.9-----15.85----11.76
61546----9.9-----14.01----12.16
61671----9.8-----12.86----8.24
61812----9.44----14.01----7.06
61937----9.09----14.13----7.06
62062----8.77----15.85----7.06
62187----8.47----18.6----7.06
62328----8.18----20.33----7.06
62453----7.91----20.33----7.06
62578----7.66----20.33----7.06
62703----7.43----20.33----7.06
62843----7.21----20.33----7.06
62968----7.20----20.33----7.06
63093----6.8-----20.33----7.06
63218----6.62----20.33----6.67
63343----6.45----20.33----6.67
63484----6.29----20.33----6.67
63609----6.13----20.33----6.67
63734----5.99----20.33----6.67
63859----5.86----20.33----6.67
63984----3.8-----20.33----6.67
64125----3.8-----20.33----6.27
64250----3.8-----14.7-----6.27
64375----3.8-----14.7-----6.67
64500----3.8-----14.7-----6.27
64625----3.8-----14.7-----6.67
64750----3.8-----14.7-----6.27
64890----3.8-----14.7-----6.67
65015----3.8-----14.7-----6.27
65140----3.8-----14.7-----6.27
65281----3.8-----14.7-----6.27
65406----3.8-----14.7-----6.27
65531----3.8-----14.7-----5.88


Before the CEL comes on, which is clearly visible here as the reading for NbO2 stops changing, the readings are fairly normal. The car also hasn't completely warmed up yet. As per usual, when I throttle in the NbO2 goes a little lean (i'm not expecting accuracy, just rich or lean) and when I throttle out, the NbO2 goes to the rich side. But that's all before the coolant temp reaches 180C.


Except when the car is fully warmed up and I let off the throttle, the NbO2 maxes out lean! It happened a little before the CEL comes on as you read the data, but then it just gets stuck there and before you know it the CEL goes on and all the data log shows is 14.7 when the ECU decides it's faulty.

I haven't touched the engine block, and I'm nearly certain the vacuum hoses are good.

What do you think?

The O2 sensor doesn't exhibit these symptoms when the coolant temp is below 180C

I just want to make sure it's my O2. And also I just started logging, so I figure doing this would be a good educational experience since I can't make sense of data that much. If anyone wants the log file, I can send it over to you.

It's almost like there's random spikes of lean, before it just gets stuck.

-edit-

ew data is hard to read, let me change it

--edit--
Data easier to read
* Registered users of the site do not see these ads.

Last edited by formula91; 03-27-2009 at 01:14 PM.
formula91 is offline   Reply With Quote
Old 03-28-2009, 01:32 PM   #2
RaceFaceXC
NASIOC Supporter
 
Member#: 165749
Join Date: Dec 2007
Chapter/Region: South East
Location: stupid Florida
Vehicle:
2007 No YELLING
on the bus!

Default

So when you lift off the accel pedal and the injectors stop injecting fuel (=AFR 20.33 displayed) it will continue to read 20.33 even after you press the accel pedal again?

How does it drive when it gets "stuck" on 20.33? normal without noticeable change? if it were really that lean performance would be way down and oil/water temps might go up shortly after

It sounds like your O2 sensor be be going bad and the problem gets bad enough when its hot to cause false O2 sensor data and trigger the CEL
RaceFaceXC is offline   Reply With Quote
Old 03-28-2009, 05:39 PM   #3
formula91
Scooby Specialist
 
Member#: 102984
Join Date: Dec 2005
Chapter/Region: MWSOC
Location: Northbrook, IL
Vehicle:
2005 2.5RS 4EAT
Platinum Silver

Default

It's hard to tell if there is any difference when the CEL light comes on. Because after the O2 sensor get stuck for a short period of time the ECU just stops listening to the O2 sensor it seems and goes into a forced OL mode of sorts. I do notice a drop in gas mileage for sure, and the car does feel a little laggy.

If you look through the data, you can see that it went to 20.33 for a couple moments before it got stuck. That happened shortly after engine load went low. But before that you can find a normal expected reading. Engine load and throttle go down and the NbO2 reads rich. Then it's almost like it slingshots to lean.
formula91 is offline   Reply With Quote
Old 03-29-2009, 08:08 PM   #4
williaty
Scooby Guru
 
Member#: 71092
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Delaware County, Ohio
Vehicle:
2005 2.5RS Wagon
Regal Blue Pearl

Default

Your "log" isn't really helping any.

Try logging AFC, AFL, AFR#1, Throttle opening angle, and CL/OL status. What I think you're going to see is that you're only ever going to see those 20.33 AFRs when AFC is 0 and CL/OL is 10. Meaning the car has gone into OL and shut off the injectors.

Really, what you'll have to do is to get the service manual and look up the correct diagnostic for this CEL. Then follow it.
williaty is offline   Reply With Quote
Old 03-29-2009, 09:37 PM   #5
formula91
Scooby Specialist
 
Member#: 102984
Join Date: Dec 2005
Chapter/Region: MWSOC
Location: Northbrook, IL
Vehicle:
2005 2.5RS 4EAT
Platinum Silver

Default

Thanks will, that was my first time ever logging something on my car, so you'll have to forgive my noobiness.

But I'll try again. I realized that I did log the wrong things. But these things that I should record does make sense. I suppose I really didn't know where to start.

And here we go one more time.

I do have a new O2 on the way, hopefully that'll fix it.
formula91 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
fuel problem, someone thats knows there stuff help me out jrlandsman Factory 2.0L Turbo Powertrain 17 03-14-2006 11:29 AM
Help me out with a woman problem (long) EdsWRX Off-Topic 10 09-20-2004 12:53 PM
2 Problems... Can ya help me out? Hassassin Tri-State Area Forum 9 01-13-2003 02:05 PM
ABS Problem Please Help Me Out legacyej22 Brakes, Steering & Suspension 0 01-03-2003 03:29 PM
Help me out with a problem Erudition General Community 1 03-22-2002 03:14 AM


All times are GMT -4. The time now is 02:59 PM.


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.