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Is my O2 sensor bad?

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dsm-onster

DSM Wiseman
8,592
130
Jul 11, 2004
Bloxom, Virginia
I have a 1990 eclipse w/ a small 16G, stock fuel pump rewired, stock MAF with lower honeycomb removed, Manual boost valve set at 15 psi with aftermarket guage.

On my scanmaster i get the following:

O2 volts: cycle ONLY at part throttle, goes to 0.0 at idle all the time no matter how long i let it idle, at WOT rises to .84 volts.

Knock count: jumps to 10+ counts quickly (at like 5 psi) goes to as high as 43 counts.

O2 trim: cycles at 165%+ range has cycled down at the 130% range but not often, never been below 120%

low, mid and high trims: always at 119% all the time no matter what.

Timing: when i do a WOT pull, starts at 40 or so the decreases steadily to -5 if i stay on the throttle. (but i don't like doing that because at that point i'm getting upwards of 40 counts of knock)

Is my O2 suspect? i get no CEL. my Motor mounts are broken, i may be getting phantom knock... what do I begin replacing?
 
try pulling out your O2 sensor and spraying it with brake cleaner. mine was doing just about the same thing.. no reading at idle and readings sometimes during partial throttle. cleaning it solved the problem though.

if that doesn't work then yeah, i would try getting a new O2 sensor.
 
Consider it done. I was able to find a bosch o2 sensor for testing as well. I will post the results tonight or tomorrow. By the way, my o2 sensor is a Denso with less then 2500 miles on it. I did run race fuel on it tho???
 
dsm-onster said:
Timing: when i do a WOT pull, starts at 40 or so the decreases steadily to -5 if i stay on the throttle. (but i don't like doing that because at that point i'm getting upwards of 40 counts of knock)

Holy .... I had to re-read that. That is the reason I am not driving my car until I get this resolved.
 
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