Welcome to the North American Subaru Impreza Owners Club Wednesday April 1, 2015
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
New England Subaru Impreza Club
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 Chapters > New England Impreza Club Forum -- NESIC

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 03-22-2006, 02:08 PM   #1
webkris
NASIOC Supporter
 
Member#: 70
Join Date: Jul 1999
Chapter/Region: NESIC
Location: Long Beach, CA
Vehicle:
I sold WRX to buy
Dodge Neon Rally Car

Question I know you guys will know... Is my O2 sensor bad?

Take a look - this is data logged from OBD2 (an Alex Peper unit)
The front O2 keeps dropping to almost no voltage - steady at .7X then down to nothing. This is after warming the car up for a bit. (10 min OR 600 seconds)

Does anyone have reason to believe that it's anything besides the sensor or wiring? I got a 'System Too Lean' code earlier in the day.

I asked the Neon kids - and no answer for days...
All I want is confirmation that I know what I'm talking about.



Thanks!
- Kris
* Registered users of the site do not see these ads.
webkris is offline   Reply With Quote
Old 03-22-2006, 03:04 PM   #2
Chromer
Scooby Specialist
 
Member#: 20325
Join Date: Jun 2002
Chapter/Region: NESIC
Vehicle:
08 Yamaha WR250R
07 Suzuki DL650

Default

Looks like probably an intermittent connector or a partially broken wire. Unplug, clean contacts on both halves of the connector, grease the plug, put it back together, and re-test. If it still does it, replacement time.
Chromer is offline   Reply With Quote
Old 03-22-2006, 04:30 PM   #3
02SilvaWagon
Scooby Specialist
 
Member#: 33933
Join Date: Mar 2003
Chapter/Region: NESIC
Location: Nashua NH
Vehicle:
2011 WRX Limited
WRB

Default

I had the same problem on my old 2002 WRX. Would read from .5 to 1.0 then would drop to 0 for a few seconds. The car seemed to be running a little different too. I fixed the problem by trading the car in.
02SilvaWagon is offline   Reply With Quote
Old 03-22-2006, 04:33 PM   #4
JoBoo
Scooby Specialist
 
Member#: 23423
Join Date: Aug 2002
Chapter/Region: NESIC
Location: slummahvul,ma www.comscc.org
Vehicle:
05 STi / 08 Dmax
IDP Racing Tech Monkey

Default

find the wiring. take a multi meter (or a scope if you have one..) and probe the wires to see if you see voltage oscillations. It could be a fault in the wiring somwhere inbetween the sensor and the ECU. Start at the sensor wiring and go back to towards teh ecu and see where you start getting voltage fluctuations.

Not saying you dont have a bad sensor, but this is an easy thing to do to rule out its not bad wiring.. and cheaper...

To find the voltages, it depends on the type of O2 sensor you have. there are a few types out there. 2 wire, 4 wire... the expected voltages also vary with the different types. Typically there is at least one signal wire. depending on the type, there may be an isolated ground wire, or it uses the chassis ground. another type may have 2 signal wires and the signal that the ecu reads is the difference of the 2. Do some searching on what you have and search for the wiring schematic for that sensor. usually in the factory maintence manual you can find it.
JoBoo is offline   Reply With Quote
Old 03-22-2006, 05:10 PM   #5
Fitz
Scooby Guru
 
Member#: 1426
Join Date: May 2000
Chapter/Region: NESIC
Location: New Boston, NH
Vehicle:
'07 335xi, '07 ZX6R
SV650 Race Bike

Default

Member number 70..... jesus I feel old.

I'll echo zip4zat. Find out what voltage the sesor should be. If it's a 0-1 volt sensor it looks ok to me.

Does ze'neon have two o2 sensors like the subaru?

Fitz
Fitz is offline   Reply With Quote
Old 03-22-2006, 05:48 PM   #6
JoBoo
Scooby Specialist
 
Member#: 23423
Join Date: Aug 2002
Chapter/Region: NESIC
Location: slummahvul,ma www.comscc.org
Vehicle:
05 STi / 08 Dmax
IDP Racing Tech Monkey

Default

the O2S12 sensor looks like its stuck on hi, it should flip between there (0.7v) and 0v. with the exhaust timing...

if there is 2 sensors and this one is the 2nd one... (post cat...dont know how these damm american cars are set up...) then I wouldnt worry about it, as long as you dont have a CEL. probably just a cat inefficiency sensor, and the ecu doesnt use it.
JoBoo is offline   Reply With Quote
Old 03-22-2006, 08:09 PM   #7
webkris
NASIOC Supporter
 
Member#: 70
Join Date: Jul 1999
Chapter/Region: NESIC
Location: Long Beach, CA
Vehicle:
I sold WRX to buy
Dodge Neon Rally Car

Default

Interesting Zip4Zat...

Before I ran this test I would have put cash money on the O2 after the cat (O2S12) being bad. It is the rallycar after all and I have chewed through the wires and shorted that baby to ground on more then one occasion. boulder hits skidplate, skidplate hits midpipe, midpipe pushes sensor wires, sensor wires hit chassis, etc

So - to say again - This is monitoring the sensors after running for 10 minutes in the driveway at idle, not moving, and no throttle.

I've been looking for my sensor voltage in AllData for about an hour now - and nothing. I did find the 4-7 Ohm heater circuit test...
Zip - you say the rear O2 is stuck high and the front is working okay?
Popping up and down in the voltage range like that?? Just seems weird. Like I said though, it's more likely the rear O2 is bad.

I am getting a CEL - and it's a "condition lean"
I can't see that as really the case - from the smell of it she's running "stupid rich".

Thanks for the help!
- Kris

Oh and Mark, the big three oh is in a month for me...
webkris is offline   Reply With Quote
Old 03-22-2006, 08:24 PM   #8
JoBoo
Scooby Specialist
 
Member#: 23423
Join Date: Aug 2002
Chapter/Region: NESIC
Location: slummahvul,ma www.comscc.org
Vehicle:
05 STi / 08 Dmax
IDP Racing Tech Monkey

Default

I cant tell you for sure what the symptoms mean without knowing the circutry in your car.

In the wrx, only the front O2 gives feed back to the ecu on fuel and maybe timing. the rear O2 is strictly for emissions. if your getting a cel for too rich/lean, then either its working and you are running rich or lean, or the O2 has gotten "lazy" which is also common. Lazy = alive, but not reading properly.. maybe due to soot, deposits, damage, or just plain age... from the chart it looks like the first one is reading something, but the second one is not. From the graph, I dont know which is front or rear...

Best thing to do is check the wiring diagram for your car, and see what things are supposed to do, then test things one by one... process of elimination is the best course. key is understanding what the proper behavior is.

do a search on the web... this is an age old problem since the introduction of O2 sensors.. theres lots of info on types, proper behavior and ways to diagnose the problems...

edit:
from what I know, most late model O2's switch back and forth between a "high" voltage, and "low" voltage. for example high can be >0.7v and low can be <0.2v the actual voltages vary by sensor type. the reason they fluctuate is because of the exhaust valve timing you get pulses of gas not a continous stream. so in those pulses you have instantaneously rich and lean gas passing by the sensor. it should read that fast and see that. if not it can give you a faulty reading = lazy...
JoBoo is offline   Reply With Quote
Old 03-22-2006, 08:29 PM   #9
JoBoo
Scooby Specialist
 
Member#: 23423
Join Date: Aug 2002
Chapter/Region: NESIC
Location: slummahvul,ma www.comscc.org
Vehicle:
05 STi / 08 Dmax
IDP Racing Tech Monkey

Default

oh and btw, you shouldnt have bought a neon...
JoBoo 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
Is my O2 sensor bad? code3suby Service & Maintenance 1 02-11-2009 01:51 PM
I know you guys will love my CORRECT wheel fitment kcb316 Texas Impreza Club Forum -- TXIC 12 02-29-2008 09:47 PM
where is my O2 sensor????? Matthew Adorjan General Community 1 11-18-2002 02:51 PM
Is my O2 sensor going south? 2.5GT Normally Aspirated Powertrain 1 09-24-2002 02:45 AM
is my O2 sensor damaged? baldcherub Service & Maintenance 2 12-22-2001 04:37 PM


All times are GMT -4. The time now is 12:47 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2015 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.