LT1-LT4 Modifications 1993-97 Gen II Small Block V8

o2 sensor issues

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Old Jun 21, 2012 | 10:56 PM
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Default o2 sensor issues

i seem to be having o2 sensor issues but they arent setting a code... the sensors are bouncing all over the place. Drivers side more then passenger..

also car smells rich

time for new ones?

i have an idle log if anyone wants to see it...
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Old Jun 22, 2012 | 04:28 AM
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If it's in closed loop they should be bouncing wildly from .1xx to .9xx. That's how they're supposed to act. Only in open loop should they read steady (they are warming up).

"Smelling" rich is a very inaccurate way of determining how a car is running. I'd only be concerned with the smell if it was at the front of the car or raw fuel is pouring out the exhaust pipes.
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Old Jun 22, 2012 | 07:46 AM
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Funny you mention this, as my car is having a similar issue. It's at PCM for less right now about to be dyno tuned....but the tuner mentions: "It looks like the reason why the car has been running rich is because the passenger side O2 sensor isn't quite up to health. That side is maxed out lean and adding the as much fuel as it can. The left side is working properly and only averaging 3-5% off from perfect. We can put a new O2 sensor in it on the right side and see if that clears it up. Sometimes its not the o2 sensor its the wiring going down to the O2 sensor since it runs so close to the header on that side. "

So for several months now I've been wrongly blaming my mail order tune for being too rich So he's throwing in a new O2 today and seeing what happens....hopefully it's not the wiring that's a problem. I replaced both O2's about 2 years ago...seems odd it's already acting crazy. I'll let you know how it does with a new O2.
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Old Jun 23, 2012 | 11:15 AM
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Originally Posted by RamAir95TA
If it's in closed loop they should be bouncing wildly from .1xx to .9xx. That's how they're supposed to act. Only in open loop should they read steady (they are warming up).

"Smelling" rich is a very inaccurate way of determining how a car is running. I'd only be concerned with the smell if it was at the front of the car or raw fuel is pouring out the exhaust pipes.
yes it was in open loop.. Thanks for clarifying.

it has no cat so thats probably 80% of the smell and no its not dumping fuel outa the exhaust lol. whats a good brand of wide band o2 sensor?
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Old Jun 23, 2012 | 12:38 PM
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Wide band O2s are used for aftermarket air/fuel ratio gauges, not for the PCM. You need OEM narrow band sensors like the AFS75.
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Old Jun 23, 2012 | 01:16 PM
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Afs75:
http://www.gmpartsdirect.com/results.cfm
Gotta love it when the RIGHT **** is cheaper than the wrong ****.
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Old Jun 25, 2012 | 08:00 PM
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sorry shoulda clarrified i want a wideband so i can tune...
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Old Jun 25, 2012 | 08:42 PM
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The AEM is a great product.
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