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Old 09-26-2006, 09:49 PM   #1
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Default Is my o2 sensor dead/dying?

I just can't figure out if this is a coincidence or not. Friday night before the dyno day meetup i swapped in my green top supra injectors. Changed the correction factor in my emanage, started up perfectly ran great. Noticed however that my a/f gauge is no long sweeping ad idle when warmed up. It did sweep during cruise conditions and showed on the rich side when boosting(autotune). It also began idling funny after sitting for a little period of time, drive again everything ok. Saturday morning went the dyno ran fine showed everything was working on the dyno's wideband. Now the past few days it's been real bad in the morning before getting warmed up, even after warming up idle is worse too. I ordered a new o2 sensor, anyone else have any ideas?
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Old 09-27-2006, 01:55 AM   #2
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Doubt the O2 sensor is dead or would have a CEL light. For $19.95 is easy enough to replace since it will degrade some over time. Any O2 sensor will not produce a signal until it is warmed up properly, and if a signal is produced it is ignored by the ECU anyway until the engine is fully warmed up and enters closed loop. Is also not read during idle.
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Old 09-27-2006, 09:14 AM   #3
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Were the new injectors cleaned and tested before installation? Did you replace the lost washer? Might be vacuum leak.
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Old 09-27-2006, 09:23 AM   #4
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yeah the injectors were cleaned/tested/and have new hardware. the one seal i haven't replaced but i'm not thinking it's leaking, i am replacing it anyway. Yes I know the o2 sensor won't read anything till warmed up and it still won't read anything without throttle, it did before. I know it doesn't seem to make sense since before warmed up the computer doesn't look at the o2 sensor but it seems to get worse after it's warmed up
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Old 09-27-2006, 09:28 AM   #5
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I'd put my money on the injectors/seals. When my o2 sensor died, it just stopped putting out any read reading whatsoever. I tested the output with a voltmeter after the car was warmed up and it read a constant 0.0034v. Odd thing was that I did not get a CEL.

Could be not sweeping b/c you are running rich off the scale from the larger injectors? Or off the scale b/c a seal leak?
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Old 09-27-2006, 09:30 AM   #6
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I don't remember if you have a 4 wire or not. If it is a single wire, try running a ground wire temporarily from the base of the O2 to the ECU ground and see if it changes. If you get a change, there is a break in the ground circuit along the way.
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Old 09-27-2006, 09:48 AM   #7
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my .02 is you're too rich at idle. I would let the car sit at idle a while until it runs poorly, then immediately check the plugs. I suspect they foul at idle.
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