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Old 05-08-2001, 08:40 PM   #1
Kevin Thomas
Street Racing Instructor
Moderator
 
Member#: 110
Join Date: Jul 1999
Location: 1997 OBS, 1996 SVX, 1988 RX
Vehicle:
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?
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Old 05-08-2001, 09:08 PM   #2
FLUBYUx2
Scooby Newbie
 
Member#: 3856
Join Date: Jan 2001
Location: St. Pete, Fla
Vehicle:
2001 Impreza 2.5RS
sedona red pearl

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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)

thanks

chris
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