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Discussion Starter · #1 ·
So I have a 97 thunderbird LX with the 4.6l, and I'm very very new to this car. The purchase opportunity sorta fell into my lap, so I have been just getting used to things.

I'm running Forscan on a BAFX obd2 Bluetooth device, just logging data and getting things set.

I noticed today that my Bank 1 Sensor 2 (B1S2) seems to read low, if any voltage until the car is at operating temp. Then proceeds to really only read during moderate or higher engine load.

By contrast B2S2 seems to read more consistently throughout all operation, having less reading when low load is on the motor, but nowhere near as low as B1S2.

Are the voltage patterns in these sensors supposed to differ so greatly?

Below are my screenshots. They are in order as Bank 1 Sensor 1, B1S2, B2S1, and B2S2 respectively
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Some of what you are observing is expected. O2 sensors do not work until they are hot; there are built-in heater elements to speed up that process, in addition to the "natural" warming caused by the passing of hot exhaust gases.

If the O2s are original, you may want to consider replacing them. As they age they will start to do what you are seeing as well - reporting a different AFR than reality, causing the switching point for closed loop operation to be skewed. Fortunately in your case, the O2 that seems to be misbehaving is the downstream O2 which has little effect on driveability.
 

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Discussion Starter · #3 ·
Good to know. Though the car is a one-owner in excellent shape at 104k miles, I'd guess they're original. Pricing on them isn't too rough, so I may just run them all.

Are they difficult to do on this chassis? I'm largely accustomed to 8th and 9th gen Ford trucks, so this is new territory for me.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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The only one that you're going to hate yourself for trying to do is the passenger upstream. An O2 socket and crow's foot will help.
 

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Discussion Starter · #5 ·
Good to know, I'll make a tool trip before I go for it.

Worth it though. This is the best condition vehicle I've ever owned by a long shot, so proactive maintainance is the name of the game.
 

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I use an adjustible wrench to pop them loose, then use the wires to remove them. I replace the fronts, and move the fronts to the rear.

NTK is the oem, and last so much longer than bosch.
 
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If you have a "heater" error from them, you should replace it and do the drive test, and see if the whole system is working better.
The heater circuit will keep the other ones from working properly.
 

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Discussion Starter · #9 ·
If you have a "heater" error from them, you should replace it and do the drive test, and see if the whole system is working better.
The heater circuit will keep the other ones from working properly.
That's a good point to test. I'll take a look, I know there is a heater test in forscan to run.
 
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