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Help with 02's

This is a discussion on Help with 02's within the General Help forums, part of the LSx Technical Help Section category; i just replace my o2 sensors and now the car is running rich, the rear gauge reads 14.7-14.8 idleing and ...

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    Member Edward-T's Avatar
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    Help with 02's

    i just replace my o2 sensors and now the car is running rich, the rear gauge reads 14.7-14.8 idleing and going down the road but the front o2 gauge is way on the rich side on idle and cruising, when i put them in it was just idle but now its both, is it a bad connection or shitty tune, i just had it tuned not a month ago, smells rich and smokes out the back, bad injectors? i dont know.

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    None Shall Pass Knight's Avatar
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    Is it one side reading bad? If so, switch the O2s and see if the problem follows.

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    Front and rear? Can you please clarify?

    Their are four (4) O2 sensors on our cars. Two (2) that are upstream (in front of) the catalytic converters and two (2) that are downstream (behind) the converters. The upstream sensors provide feedback to the PCM to control fueling in closed loop operation. The downstream sensors simply tell the PCM if the converters are working properly and have no affect on fueling. Also, the sensors are "narrowband" and do not provide any useable data for us to determine an engine's actual air-fuel ratio as they very rapidly cycle up and down.

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    Member Edward-T's Avatar
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    it is the front 2, i only have 3 total as i have long tubes and a ory, plus a cam and heads and a tune, when i got off work yesterday evening it was fine all the way home, not rich or anything, i took off from the end of the exit ramp and spun through first and most of second and barked em real good in third and it still didnt run rich then either, i noticed its not switching back and forth rapidly like it was when i first installed them, you think its the cold morning air maybe? also over the weekend i cleaned my mass air flow and the air filter, i used the mass air flow cleaner in a spray can and didnt touch anything, also the tuner said my injectors were at 95% duty cycle, could that be the problem?

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    Not sure why you would have 3 sensors with an ORY. Do you have an aftermarket air-fuel gauge installed in the car?

    If you are watching the live sensor data, after the engine is up to temp, and it is acting sluggish, you may have defective or worn out sensors. Do you run an extension harness to the sensors? If so, get rid of them and install a set of Bosch 13111 sensors as they have a nice long harness and work great with LT's.

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    Member Edward-T's Avatar
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    yes i have a gauge for the front 02 sensors which usually goes from lean to rich rapidly and constantly and i have a rear gauge that reads the rich and lean and its a digital that usually stays on 14.7-14.8 after its warmed up. i just bought the sensors this past weekend and installed them and the ends were to short so i had to splice into them and add wire to get the correct length, this was how it was on the old sensors as well and they worked since i bought the car in April. the front 2 sensors are in the headers right before the collectors and the rear sensor is right at the back wheel before it goes over the axle.

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    None Shall Pass Knight's Avatar
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    Get rid of the splices. More than likely, that is the cause. As Jeff stated, get some Bosch 13111s. Hopefully you didn't cut the factory plug off, as the new O2s will simply plug right in. The front O2 sensors are the only ones that will affect the cars performance.

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    Member Edward-T's Avatar
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    ok, i will try that, but as far as performance goes it still runs like a top, strong and fast, just rich as hell.

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    the bungs where the 02's go in to the headers may need to be moved... the 02s should be replaced with longer corded ones or 02 extentions should be installed... another thing is to make sure the 02 wires aren't resting against the header...

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    Member Edward-T's Avatar
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    The wires were againts the headers on driver side, thought I zip tied them out of the way. I rewired and recrimped all with new wires, runs great and switches from lean to rich rapidly while cruising and getting on it( I busted a wrx on the test run, he had his girl with him to, lol) still a little slow switching from lean to rich at idle but its a definate improvement.

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    Member Edward-T's Avatar
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    The wires were on the header, thought I had them zip tied out of the way. Ran new wires and spliced and crimped them in-until I get the ones you guys suggested. Switches lean to rich rapidly while cruising and while dogging it (busted a wrx on test drive, he had his girl with him too, lol) still a little slow switching from lean to rich at idle but its a huge improvement over the way it was doing.

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    O U 8 1 2 Spaz's Avatar
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    Quote Originally Posted by Edward-T View Post
    The wires were on the header, thought I had them zip tied out of the way. Ran new wires and spliced and crimped them in-until I get the ones you guys suggested. Switches lean to rich rapidly while cruising and while dogging it (busted a wrx on test drive, he had his girl with him too, lol) still a little slow switching from lean to rich at idle but its a huge improvement over the way it was doing.
    i hope that solves the problem!!!

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