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HowardRoark

Help - O2 monitor needs to set

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Hello all,

Just had the engine completely rebuilt, and I need to get the car ready to pass the SMOG test here in California. My tech was able to set all monitors except the Oxygen sensor. I have driven it about 150 miles, and it still hasn't set. I have heard a few different theories: To drive in 5th gear between 45-55 mph for 20 minutes, or to drive it in 5th gear at 35 mph for a few minutes. Does anyone know for sure how to get the O2 monitor set?

Cheers!

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Just to close this thread, I finally got the O2 monitor to set! I drove it for a few minutes at 35 mph in 5th gear, and I think that did it.

Cheers

post-9481-0-61335000-1425865282.jpg

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Yes, that's the trick 35 MPH in 5th gear up a long slight hill, almost lugging the engine. That's the drive cycle for the O2 readiness test.

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Thanks for the advice Wayne. Even my exotic auto shop down here in San Diego didn't know how to set it. :)

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I am having running problems and suspect my post O2 sensors but I can't the O2 monitor to reset or start working. I don't have a road long enough, it's either too short to road conditions mean it's too fast. Any ideas?

My pre cat sensors are working but post are intermittent. When they drop down to nearly zero volts then that when I have running issues. Blip the throttle and voltage goes back upto 0.8-0.9 volts and all runs fine.

BTW, did you have any running problems before you set your O2 sensor monitor?

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Dave are you actually watching the o2 sensor switching times and voltage levels. what are you using to "watch " the o2 sensors?

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Hi Wayne,

I am using Gendan software. The O2 Sensor monitor still say incomplete and when I check all four sensor voltages, both pre fluctuate from 0.1 to 0.9 but the post seem to fluctuate less at 0.8-0.9. They all of a sudden the post voltage drops off to 0.1 then I get my misfire. Give it a good rev and the volts come back to life again and engine runs fine. I suspect a break in the wire (green I think)?

David

PS I've also tried the software on here too

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Sorry for the delay. There must be something else going on. The post CAT sensor's only function is to let the ECU know how the CATs are functioning, they don't control anything. A misfire is being caused by some condition (fuel mixture, or timing,) and the post sensors are re-acting to it. Maybe very rich mixture finding its way into the CAT and being lit off by the heat in the CAT??

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Hi Wayne,

It's not a backfire more like hesitation. As this happens, the volts to the post O2 sensors go to zero. It's all goes right as soon as volts rise back upto 0.85V.

 

Regards,

 

David

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