I have been scouring the internet and have decided I have a weird problem. I want to get someone to agree with me or give me something I haven't thought of yet.
I bought the 1998 TJ from a used car lot. It had a check engine light on on the test drive. They assured me that it was just an 02 sensor and they were going to replace it before I bought it. When I picked it up it the light was off and everything seemed ok. The next day when I started it check engine light came back on and it was a 02 heater circuit. I then looked at both of the 02 sensors and they looked new, but I have been reading that if you use bosch 02 sensors that they could be bad, so I decided I was going to fix this by going to dealer and getting dealer parts. I replaced both 02 sensors. The ones I pulled were brand new.
Sure enough the next day fired it up in the morning and 02 heater circuit code. Now keep in mind it has a rough idle cold and bucks and jumps driving down the first street after I reset the code. Then on the second street runs fine and no issues the rest of the day even after sitting 8-10 hours at work. It is completely fine till the next day. The next morning wether I park in the garage or outside check engine light in the morning.
so I have tried a couple of mornings that if I start it and immediately rev the motor to 2k and keep it there for 2 minutes no check engine light. I am not sure if it is coincidence yet or if it was just two days of no check engine light.
Wether or not I have a check engine light it idles rough and bucks and jumps down the first road on my way to work. I have read that the IAC being dirty could cause this, but also if the 02 sensors are not reading right the ECU will try and adjust and I am leaning to that as being the issue.
So the 02 sensors have been replaced twice with no change. I doubt it is the ECU because this seems to be the only issue and usually of the ECU is bad weird things happen and this seems to be consistent.
This is my best guess now. I am thinking that the harness between the front 02 sensor and the ECU might have an issue so I think I need to test the 02 at the plug then plug it in and test it at the ECU and see if it is consistent. If it is consistent. I am out of ideas if it isn't looks like I may have a bad wire reporting to the ECU. I got up on ebay and ordered a service manual, and am waiting for it to get here. My biggest hurdle is it hasn't been below 108 degrees here for over a week and it is just too hot to diagnose wiring issues under the hood right now.
Do you think that reving the motor for 2 minutes might help? Also it seems to be getting terrible gas mileage. I mean I haven't checked it but I am only getting about 160miles to a tank of gas, but the tank is pretty small. Might be normal not sure. And lastly does that plan of attack seem right? Or I am open to any suggestions.
1998 TJ 4.0, 5sp, red everything pretty much stock.
Thanks in advance.
I bought the 1998 TJ from a used car lot. It had a check engine light on on the test drive. They assured me that it was just an 02 sensor and they were going to replace it before I bought it. When I picked it up it the light was off and everything seemed ok. The next day when I started it check engine light came back on and it was a 02 heater circuit. I then looked at both of the 02 sensors and they looked new, but I have been reading that if you use bosch 02 sensors that they could be bad, so I decided I was going to fix this by going to dealer and getting dealer parts. I replaced both 02 sensors. The ones I pulled were brand new.
Sure enough the next day fired it up in the morning and 02 heater circuit code. Now keep in mind it has a rough idle cold and bucks and jumps driving down the first street after I reset the code. Then on the second street runs fine and no issues the rest of the day even after sitting 8-10 hours at work. It is completely fine till the next day. The next morning wether I park in the garage or outside check engine light in the morning.
so I have tried a couple of mornings that if I start it and immediately rev the motor to 2k and keep it there for 2 minutes no check engine light. I am not sure if it is coincidence yet or if it was just two days of no check engine light.
Wether or not I have a check engine light it idles rough and bucks and jumps down the first road on my way to work. I have read that the IAC being dirty could cause this, but also if the 02 sensors are not reading right the ECU will try and adjust and I am leaning to that as being the issue.
So the 02 sensors have been replaced twice with no change. I doubt it is the ECU because this seems to be the only issue and usually of the ECU is bad weird things happen and this seems to be consistent.
This is my best guess now. I am thinking that the harness between the front 02 sensor and the ECU might have an issue so I think I need to test the 02 at the plug then plug it in and test it at the ECU and see if it is consistent. If it is consistent. I am out of ideas if it isn't looks like I may have a bad wire reporting to the ECU. I got up on ebay and ordered a service manual, and am waiting for it to get here. My biggest hurdle is it hasn't been below 108 degrees here for over a week and it is just too hot to diagnose wiring issues under the hood right now.
Do you think that reving the motor for 2 minutes might help? Also it seems to be getting terrible gas mileage. I mean I haven't checked it but I am only getting about 160miles to a tank of gas, but the tank is pretty small. Might be normal not sure. And lastly does that plan of attack seem right? Or I am open to any suggestions.
1998 TJ 4.0, 5sp, red everything pretty much stock.
Thanks in advance.
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