Welcome to the North American Subaru Impreza Owners Club Thursday October 19, 2017
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Subaru Models > Impreza Forum

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. 
Thread Tools Display Modes
Old 05-08-2001, 08:40 PM   #1
Kevin Thomas
Street Racing Instructor
Member#: 110
Join Date: Jul 1999
Location: 1997 OBS, 1996 SVX, 1988 RX
1989 1989 XT6

Question Stubborn O2 Sensor

I have been having problems with my O2 sensor for a while now. For the longest time, it would just read between .00-.01. I had my O2 sensor replaced for the 2nd time since last week. Now when I began driving on a highway or when I'm driving above 45mph, it seems to work fine. As soon as I get back into stop-n-go traffic, it fluctuates in smaller and smaller ranges (Between .00-.79), until it reaches down into the .2 range (.00-.29). It'll stay this way until I get back onto a highway or steady driving above 45mph.

What does this mean? Just for more info, I checked my spark plugs today and it seem to be that my car has been running rich (dark coloring on plugs). I replaced them but the gap seemed a little to excessive on the worn plugs and the new plugs (.043-.046). I understand that some spark plugs can affect your O2 readings by running too rich but still my O2 sensor doesn't show this. I will be purchasing a stock temp spark plug tomorrow and gapping them about 0.036". I read in a spark plug FAQ (http://www.kamsonmechanical.com.au/Tech%20Tips/do_i_need_to_set_the_gap_on_new_.htm) that when you raise compression or add forced induction (a turbo system, nitrous or supercharger kit) you must reduce the gap (about .004" for every 50 hp you add). My stock plug gap range is 0.039-0.043.

I have a Jumptronix digital air/fuel ratio meter that reads actual voltage and a HF SFC (Hyper Fuel Simple Fuel Controller) that reads lean and rich. They both are always reading the same so they are getting the same info.

What does this all mean? Why does my air/fuel ratio just die when the car is idle and then fluctuates between 0.00-0.80 or so while driving steadily, above 45mph?
* Registered users of the site do not see these ads.
Kevin Thomas is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 05-08-2001, 09:08 PM   #2
Scooby Newbie
Member#: 3856
Join Date: Jan 2001
Location: St. Pete, Fla
2001 Impreza 2.5RS
sedona red pearl


kevin...MAYBE its all that hard drivin you do...say for instance, the Cobra/camaro spankins you lay down. lol

could have something to do w/ the idle, the fuel press is down, as well as the fuel consumption, u know, lower duty cycles on the inj. and at hiway cruising, the throttle is cracked, and slightly higher (but static) inj duty cycles. and during in-town driving, its more of a broader range, from cracked throttle, to half throttle fluctuations...and even higher (but intermittent) inj duty cycles...

who know, i think im just talkin out my ass...but the big words sound cool eh? haah

on a similar note;

i had my intake wide open (NO pipe whatsoever, just the filter attached to the TB side of the airbox) and for a while, the CE lite came on...and gave me some Chugging while driving in town, and lacked serious power. i thot it was the O2 sensor...cuz the OE sensors like to pop...i took it to the Dealer, and they said it was the KNOCK sensor... anyone got input on this??? i still gotta make an appt to have it innnstalld...but right now, my CE light isnt on anymore (i put the complete intake back on, comlete w/ OE silencers)


FLUBYUx2 is offline   Reply With Quote

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
Front O2 sensor vs Rear O2 sensor (MY00 RS) Jewbaru Service & Maintenance 3 07-29-2012 10:14 PM
FS (OH): WRX/STi rear o2 sensor, MAF sensor, MAP sensor coolblue05 Engine/Power/Exhaust 14 07-07-2009 02:52 PM
can i zip tie second o2 sensor and put wideband o2 in that spot? sidwin AccessPort 2 02-11-2008 06:18 PM
PA: PDM O2 sensor extension (rear O2 - for P0420 code) Siper2 Private 'Wanted' Classifieds 0 04-16-2006 12:01 PM
o2 sensor used for wideband vs. reg o2 Stiguy247 Engine Management & Tuning 1 06-15-2005 02:22 PM

All times are GMT -4. The time now is 03:22 PM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2017 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.