Running Rich

Brian

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My 93 4.0 seems to be running rich, plus a. lot of exhaust fumes in cab. The fumes are enough to get me high. I have all new exhaust system and have checked and rechecked for leaks. Tailpipe does not extend beyond the bumper though. Thinking about an extension?

Aside from it getting in cab it smells very rich. It has been fully tuned. Using Autolite 985 plugs, maybe go to a hotter range? I pulled #1 and it looks fine (clean burn).
I appreciate and all advice.
 

machoheadgames

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Did you ever go read the code yourself? I do not trust the O'reilly parts pushers to point you to the right code. Seriously, look up the key trick and see what code you have. You will probably fix all this guesswork quick.

You don't need fancy spark plugs to avoid running rich.
 

Stoopid Jeep

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Did you ever go read the code yourself? I do not trust the O'reilly parts pushers to point you to the right code. Seriously, look up the key trick and see what code you have. You will probably fix all this guesswork quick.

You don't need fancy spark plugs to avoid running rich.
^^^This is good advice^^^
The ol' shotgun diagnoses is expensive and inefficient.
Here is a Link to "THE KEY TRICK" video.
Definitely one of the first diagnostic tools that should be utilized.
 
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Brian

Brian

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^^^This is good advice^^^
The ol' shotgun diagnoses is expensive and inefficient.
Here is a Link to "THE KEY TRICK" video.
Definitely one of the first diagnostic tools that should be utilized.
The check engine light has not come on for the last 100 miles. I flushed the fuel rail out hoping there was just a small particle in it that was causing the problem. Will check for a code again (guess it stays in system until cleared). Just had a thought.....if temp sensor is faulty, would it maybe tell ECU to run rich? What about the tailpipe, should it extend pass bumper?
 

Gilaguy23

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Not saying you have a potential issue however on my YJ that only has a softop with a semi bad rear zipper that wont close all the way, I was getting tired of the occasional fumes. I added a 90 tailpipe out the side which helped quite a bit.If yours is not even clearing the rear cross member you might try it. The 90 was $12 or so and I used a T bolt clamp to keep it in place. Yeah sure its not gonna look to good if I come off a bolder on the right rear tire but its better than having a headache after a 20 min trip down the highway.
 

machoheadgames

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The check engine light has not come on for the last 100 miles. I flushed the fuel rail out hoping there was just a small particle in it that was causing the problem. Will check for a code again (guess it stays in system until cleared). Just had a thought.....if temp sensor is faulty, would it maybe tell ECU to run rich? What about the tailpipe, should it extend pass bumper?
More often than not it doesn’t show the light. Usually shows the light of the condition gets really bad or more codes are thrown. If you still have the same problem then you probably still have a code. They don’t go away unless you pull the battery cable.

Yes, temp sensor can tell the computer you aren’t warmed up and run rich that way. Bad thermostat could also keep you from warming up. Thermostat needs to be 195.

Ideally tailpipe goes to the bumper so you smell it less but you still shouldn’t be running rich regardless.
 
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Brian

Brian

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More often than not it doesn’t show the light. Usually shows the light of the condition gets really bad or more codes are thrown. If you still have the same problem then you probably still have a code. They don’t go away unless you pull the battery cable.

Yes, temp sensor can tell the computer you aren’t warmed up and run rich that way. Bad thermostat could also keep you from warming up. Thermostat needs to be 195.

Ideally tailpipe goes to the bumper so you smell it less but you still shouldn’t be running rich regardless.
Interior gauge says 195, but. does that prove that it is sending same message to computer
 

machoheadgames

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Interior gauge says 195, but. does that prove that it is sending same message to computer
No, temp sending unit for the gauge is different from the one sending info to the computer. Still check for codes to see if you have one in memory. Ideally I’d like to see the code that the oreilly guy told you was O2 sensor. There are a few different rich codes, not sure if that guy told you O2 was the best thing to check, or if you actually had the O2 code.
 
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Brian

Brian

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No, temp sending unit for the gauge is different from the one sending info to the computer. Still check for codes to see if you have one in memory. Ideally I’d like to see the code that the oreilly guy told you was O2 sensor. There are a few different rich codes, not sure if that guy told you O2 was the best thing to check, or if you actually had the O2 code.
OK... As soon as it warms up some! It is a balmy 42 here is sunny Florida. Oh yea, did you see my driveline vibe is gone and the play is gone in steering. Fun to drive now or maybe I was just high on fumes!
 
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Brian

Brian

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OK... As soon as it warms up some! It is a balmy 42 here is sunny Florida. Oh yea, did you see my driveline vibe is gone and the play is gone in steering. Fun to drive now or maybe I was just high on fumes!
OK. Here are the codes. #12. #33. #27. #22. I know 33 is A/C related so I disregard.
Need you to translate into terms I can understand. The injector verbiage I can not understand.
 

machoheadgames

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22 - engine coolant temperature sensor voltage too high or too low
27 - injector does not respond properly to the control signal.

I would guess the running rich is due to 22. You could have a faulty injector causing the 27 but I would change the temp sensor first. The one on the thermostat housing. Once you do that, then either your "injector problem" might go away, or it might become more obvious. If you do have an injector problem, then buying 6 new ones would be the best move. Still don't know which ones would be best.

Basically your temp sensor needs to be changed and one of your injectors is not working as expected according to the computer. But sometimes the computer thinks the injectors are faulty based on running rich, which might be from the temp sensor. So change the temp sensor first and see what happens, then decide if the injectors still need to be messed with.

You probably had a code 21 before when the oreilly guy told you O2 sensor. You probably fixed that with the new O2 sensor and now are onto the next problems. Either that or he didn't read all the codes or at least didn't tell you all of them.
 
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Brian

Brian

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OK. Here are the codes. #12. #33. #27. #22. I know 33 is A/C related so I disregard.
Need you to translate into terms I can understand. The injector verbiage I can not understand.

22 - engine coolant temperature sensor voltage too high or too low
27 - injector does not respond properly to the control signal.

I would guess the running rich is due to 22. You could have a faulty injector causing the 27 but I would change the temp sensor first. The one on the thermostat housing. Once you do that, then either your "injector problem" might go away, or it might become more obvious. If you do have an injector problem, then buying 6 new ones would be the best move. Still don't know which ones would be best.

Basically your temp sensor needs to be changed and one of your injectors is not working as expected according to the computer. But sometimes the computer thinks the injectors are faulty based on running rich, which might be from the temp sensor. So change the temp sensor first and see what happens, then decide if the injectors still need to be messed with.

You probably had a code 21 before when the oreilly guy told you O2 sensor. You probably fixed that with the new O2 sensor and now are onto the next problems. Either that or he didn't read all the codes or at least didn't tell you all of them.
Will do! Thank you so much for your advice and knowledge
 

Flyer58

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After I replaced my exhaust I had a strong exhaust smell. I found the two nuts which attach the head pipe to the cast iron header were loose and I know they had been torqued properly. I'm guessing the pipe wasn't properly seated and once I made it right and retorqued the nuts the exhausts smell was gone.

I have read that even the slightest leak forward of the O2 sensor can give it a misleading reading and it may run rich.

Crawl underneath and give the exhaust a good shake to see if there's any loose connections. It should feel very solid.
 
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Brian

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After I replaced my exhaust I had a strong exhaust smell. I found the two nuts which attach the head pipe to the cast iron header were loose and I know they had been torqued properly. I'm guessing the pipe wasn't properly seated and once I made it right and retorqued the nuts the exhausts smell was gone.

I have read that even the slightest leak forward of the O2 sensor can give it a misleading reading and it may run rich.

Crawl underneath and give the exhaust a good shake to see if there's any loose connections. It should feel very solid.
Done all of the mentioned. I think Machoheadgames has the answer with the temp sensor. I had to order one for tomorrow, but I unpluged it while hot and ohm meter says open circuit between the two pins.
 
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Brian

Brian

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Will do! Thank you so much for your advice and knowledge
Changed the Temp sensor@ the thermo housing. Have not driven enough to determine if problem solved, but have questions. I checked the 1st sensor with ohm meter, and it was an open circuit whether hot or cold. Checked new sensor and got the same result. Checked the plug for voltage and got nothing. I cannot find a wiring diagram for this circuit. Do you know where wires originate? I assume there should be 12 volts coming to sensor?
 

machoheadgames

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No, it doesn't work off 12V. It works off resistance. One of the wires should go to ground and the other goes to the computer. The computer is looking for a relationship of resistance to ground. The sensor interrupts the connection between the two wires by being very resistant at low temps and lowering the resistance when the sensor warms up. Whatever ohm reading to ground the computer determines from that sensor's ohm reading, is how it knows the coolant temp.

When it's cold there should be so much resistance that I don't think you should have continuity, it would be an open circuit. And as I said there is no 12V so you definitely won't find that.

Check out this link:

CTS Test
 
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Brian

Brian

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No, it doesn't work off 12V. It works off resistance. One of the wires should go to ground and the other goes to the computer. The computer is looking for a relationship of resistance to ground. The sensor interrupts the connection between the two wires by being very resistant at low temps and lowering the resistance when the sensor warms up. Whatever ohm reading to ground the computer determines from that sensor's ohm reading, is how it knows the coolant temp.

When it's cold there should be so much resistance that I don't think you should have continuity, it would be an open circuit. And as I said there is no 12V so you definitely won't find that.

Check out this link:

CTS Test
Good Grief! You are like a walking Jeep Encyclopedia! Thanks for the info
 

machoheadgames

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Good Grief! You are like a walking Jeep Encyclopedia! Thanks for the info
Lol. 9 years of this will do that. I couldn't tell you where the AC compressor was 9 years ago. Countless hours of forum browsing (back when photobucket pics on other forums still worked), tons of YouTube videos, and reading tons of factual articles/pages about Jeeps to understand their specifics. Also, reading the factory service manual for hours on end. That was the most helpful by far, and proved wrong a lot of the people spreading misinfo over the years about the way certain things work on these Jeeps.

I imagine if you go for a drive the problem will be fixed but you may still have the code. Best thing to do is disconnect the battery to clear the code. Then you can see if the injector one comes back or if all problems are fixed.
 
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Brian

Brian

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Lol. 9 years of this will do that. I couldn't tell you where the AC compressor was 9 years ago. Countless hours of forum browsing (back when photobucket pics on other forums still worked), tons of YouTube videos, and reading tons of factual articles/pages about Jeeps to understand their specifics. Also, reading the factory service manual for hours on end. That was the most helpful by far, and proved wrong a lot of the people spreading misinfo over the years about the way certain things work on these Jeeps.

I imagine if you go for a drive the problem will be fixed but you may still have the code. Best thing to do is disconnect the battery to clear the code. Then you can see if the injector one comes back or if all problems are fixed.
Finally back to you! The new sensor seems to have done the trick. No more gas fumes and only code now is the A/C one (N/A). Did extend the tailpipe to the bumpers edge also, but it definitely was the sensor. Now, I hope I can spend more time on the appearance than mechanical. That being said..... I have some concerns with the trans, but I don't want to get into that yet. Thanks, again
 

machoheadgames

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Great to hear. It was probably detecting all that extra fuel from the bad temp sensor and thought maybe it could be an injector too. The one thing I’ve learned about these YJs is that if you have a code, it’s definitely for a reason. They never throw them for fun. It’s such an ancient system that it doesn’t even throw a code until there is a real problem so if you get one, gotta fix it. And definitely always the first step it to read them when something starts acting up, esp since it’s so easy to do.

The tailpipe extension will help sometimes idling especially in a more cramped spot.

Did you change trans fluid yet?