Recently purchased a 98 with the 2.5L. When test driving the motor did good for about 20 minutes, then the next day drove for about 30 minutes and lost power. I couldn’t get out of 3rd gear for lack of power. There was a CEL that was read to be O2 Circuit high voltage (Bank 1, Sensor 1). In research, I read that people have experienced issues similar to mine when this error is present. Ordered the NTK sensor but climbed under the jeep to find a solid pipe welded in where the sensor goes into the down pipe. I’m fairly new to Jeep community and curious if this is common. Is there something else I can do other than go to the muffler shop to get this fixed?
98 2.5L Deleted Upstream O2 Sensor
- Thread starter Whit13
- Start date
That isn’t very common to my knowledge and the only way you’re going to fix that is have a new bung welded in there and put an O2 sensor in.
I can't say that I've heard of people removing the upstream O2 sensor on the 4 popper before and honestly you need it for the computer to know how much fuel to put into the engine. What size tires does it have? Stock gearing? If everything else checks out on it then you might try loosening up a exhaust flange to see if your catalytic converter is clogged. While the 4 angry squirrels aren't known for loads of power they aren't a total dog. The one thing is that you don't drive it like a car. You need to REV the piss out of it... Keep the RPM's above 2500 most of the time before you shift and sometimes above 3000 RPM's.
I had a feeling that was going to be the response. I’ll see about getting it to the muffler shop to see if that fixes the issue.
I’m shocked someone removed the upstream sensor. They can run without the downstream sensor (though you’ll get a CEL) but without the upstream sensor they will run like crap.
It will have the power of 4 squirrels for 20-30 minutes then just sudden the power of 1. I will check the cat to see if that is causing anything. The downstream O2 is still installed.
It has 33” tires with what I believe to be stock gears. I will keep the RPMS higher than traditional vehicles when shifting.
Once you get the engine issue figured out you'll want to regear it 4.88 or 5.13 and you'll be happier with 5.13 gears.
I’ve found in my research I found multiple people have removed the downstream but not the upstream. Whoever removed it did a hack job on welding the pipe to the flange so it needs redone.
One thing that can be expected when buying a jeep. A 90% chance an clueless idiot had their hands on it at some point making it "better" You can also buy a clamp on 02 sensor bung from Summit or several other vendors if a muff shop is no close. Of course welding one in is best but sometimes ya gotta do what you gotta do in a pinch. Is the wiring still there to plug into the sensor or did they hack it off to save 2 grams of weight?
The plugs is still there, so dropping it off tomorrow at the muffler shop. I planned on taking it soon anyways as there is an awful exhaust leak from where the new section of pipe is welded to the flange. Whoever welded the flange on did a hack job that looks like a 5 year old welded it.
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