Which o2 sensor should be changed on my Jeep Cherokee 98, 4 L? There's 2.
#16
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Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
You can get the wrench set (which will have both styles) as a loaner tool from your local auto parts store - but they're inexpensive enough that buying one is just as good.
Hopefully since you're in the LA area the rust is not too bad and it will come out without too much trouble.
#17
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Model: Cherokee (XJ)
Thank you RocketMouse, I really appreciate it.
Unfortunately, I think my jeep may have a problem that I'm not going to be able to fix myself.
Originally, I thought that O2 was the cause of my poor mileage, but it seems that something is going on in the fuel tank. Yesterday, my gas gauge showed EMPTY, so I turned my jeep off and then back on again, and then it showed the correct amount of gas, which was 1/4. Inside my tank I hear some strange noise, is it the floater?? Fuel pump?? Something is obviously not measuring the amount of gas correctly, and sending the wrong info to the gas gauge. What do you guys think? Thank you in advance.
Unfortunately, I think my jeep may have a problem that I'm not going to be able to fix myself.
Originally, I thought that O2 was the cause of my poor mileage, but it seems that something is going on in the fuel tank. Yesterday, my gas gauge showed EMPTY, so I turned my jeep off and then back on again, and then it showed the correct amount of gas, which was 1/4. Inside my tank I hear some strange noise, is it the floater?? Fuel pump?? Something is obviously not measuring the amount of gas correctly, and sending the wrong info to the gas gauge. What do you guys think? Thank you in advance.
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Thank you. PatHenry.
You're right: not too much rust on my jeep, even though I purchased it used in Utah about 11 years ago.
But, the O2 sensor may not be my problem now. Something weird is going on inside the tank. I posted it to RocketMouse.
You're right: not too much rust on my jeep, even though I purchased it used in Utah about 11 years ago.
But, the O2 sensor may not be my problem now. Something weird is going on inside the tank. I posted it to RocketMouse.
#19
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Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
You can normally hear the fuel pump prime as you're starting the Jeep. It's a mild humming type sound. The fuel pump and sender are integrated into the assembly inside the gas tank. I wouldn't think that a problem with the fuel pump or assembly would cause poor mileage - usually it's poor engine operation that indicates a bad pump. The sending unit and float mechanism can have issues and cause the erratic gauge behavior. However, If you turned the key off and back on and the gauge read correctly, I think you might have a wiring issue or gauge issue which I would check out first (since you have to drop the tank to get at the pump assembly.. also the assembly should be replaced as an assembly so it's a pretty pricey part on top of the difficulty in getting to it.).
Watch the gauges on startup and see if the fuel gauge reads empty again and note whether it had jumped up like the other gauges or if it was flat zero the whole time - the gauges should all spike up on startup before settling on a 98, if the gauge does spike and read zero, I'd suspect sending unit, if it's flat zero then gauge/wiring.
I'm not an expert though, so maybe someone has better advice.
Last edited by PatHenry; 05-09-2018 at 03:24 PM.
#20
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Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Janko, you are probably seeing two separate problems. Maybe. Or maybe not.
By the way, before I get into that, the tip about heating the pipe to remove the O2 sensor is right on the money. They are almost impossible to get out otherwise. If you don't have a torch, you can just drive around until the beast is up to full temperature, then attack it quickly.
Now, to your (possible) two problems:
How are you measuring your fuel economy?
The reason I'm asking is that fuel gauges are notoriously inaccurate. The only correct way to assess your fuel economy is the first method.
If you are using the second method, forget the O2 sensor (for now) and deal with the sending unit.
You might find there's no other problem.
By the way, before I get into that, the tip about heating the pipe to remove the O2 sensor is right on the money. They are almost impossible to get out otherwise. If you don't have a torch, you can just drive around until the beast is up to full temperature, then attack it quickly.
Now, to your (possible) two problems:
How are you measuring your fuel economy?
- Are you recording the miles on the odometer and the fuel pumped in at the pump, as reported on the pump?
- OR, are you going by the gauge and the miles driven?
The reason I'm asking is that fuel gauges are notoriously inaccurate. The only correct way to assess your fuel economy is the first method.
If you are using the second method, forget the O2 sensor (for now) and deal with the sending unit.
You might find there's no other problem.
#21
I just replaced my upstream o2 due to poor fuel mileage and blowing black smoke and hesitating at temp. That Fixed all 3 problems, but gave me a new one. It won't rev past 3300 rpm when accelerating.
#22
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Another tip for removing the old 02. As long as it's not being reused you could break it off so a regular socket will fit on it. Apply a little heat. Then with an impact, give a quick pull of the trigger with it on tighten. Then proceed to remove. A lot of time that quick blast in forward will help break it free.
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