92 f-150
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92 f-150
Okay while back my truck was running really bad and it wouldn't start up it up everytime reliably and that was due to a bad ECT sensor, but being that the ect sensor was bad and was causing a rich condition on the truck would that burn out the O2 sensor on the truck even if the computer doesn't throw a code for it???
This is on a 92 F-150 302EFI
This is on a 92 F-150 302EFI
Thread Starter
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Posting Guru
Joined: Jun 2002
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O2 sensor???
Can you have a bad o2 sensor and not know it? I was wanting to know does the o2 sensor when it is going bad always throw a code and if it doesn't always have to throw a code to be bad, what is a good multimeter on it to see if it's working properly???
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Warm the truck up and run a KOER test. The computer will test that all the sensors are "go" for a warmed-up engine, that the oxygen sensor is capable of reading "rich" and "lean" and that it is working well enough for the computer to run in closed-loop mode. If KOER passes without codes, the sensor is not grossly broken.
The sensors get "slow" after enough age. They take too long to react to changes in the amount of oxygen, and your engine goes from switching from "rich" to "lean" at 10 hz down to something like 3 hz. This may not set a code, but the engine will run rougher and gas mileage will degrade slightly.
A normal oxygen sensor reads about 1 volt when rich, about 0.1 volt when lean, and about 0.4 volts at stoichiometric. In closed-loop operation, viewing it with an oscilloscope, you would see a square wave from 1 volt to 0.1 volt and back again at about a 10 hz rate.
With a scanner you can get "cross counts", which is a good way to know that closed-loop is working and whether the oxygen sensor is getting tired.
The sensors get "slow" after enough age. They take too long to react to changes in the amount of oxygen, and your engine goes from switching from "rich" to "lean" at 10 hz down to something like 3 hz. This may not set a code, but the engine will run rougher and gas mileage will degrade slightly.
A normal oxygen sensor reads about 1 volt when rich, about 0.1 volt when lean, and about 0.4 volts at stoichiometric. In closed-loop operation, viewing it with an oscilloscope, you would see a square wave from 1 volt to 0.1 volt and back again at about a 10 hz rate.
With a scanner you can get "cross counts", which is a good way to know that closed-loop is working and whether the oxygen sensor is getting tired.
