Smell going uphill

MrBClark

MrBClark

TJ Enthusiast
Joined
Mar 30, 2019
Messages
300
Location
Montoursville Pennsylvania
So when I go up a hill in my Jeep, it gives off a rotten egg type smell. My Jeep recently had a bad catalytic converter code. Tried spark plugs first. Ended up changing all the cats (2001 Jeep). The smell is still there at times and I'm stumped. It also gets a little warm going up larger hills. Not hot, just a bit over 210. Another thing is that when it is at a hot idle, the temp will also increase a bit. Here is a picture of a hot idle.
20200702_164817.jpg
 
So the things I want help with is:

Why does my Jeep get a little warm going up hills and at idle?

Why is the strange smell there even after i changed all 3 of my cats?

I have not been burning coolant and haven't been burning much oil at all. Its a 2001 4.0 with the NV3550.
 
Could smell that be gasoline fumes? My thought is there's a bad upstream O2 sensor causing the air fuel mixture to have gone full rich.

If you replace them make sure you only install NTK and definitely not Bosch.
 
Jerry Bransford said:
Could smell that be gasoline fumes? My thought is there's a bad upstream O2 sensor causing the air fuel mixture to have gone full rich.

If you replace them make sure you only install NTK and definitely not Bosch.
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Wouldn't it throw a code for those? That has to be what it is though. I can't think of anything else. How hard are the two upstream 02 sensors to replace? I feel like they would be awful with the intake...
 
Actually I feel like it may just be because the converters are so new. Part of their "break-in" process. If it's not gone in like a month then I will be a bit more worried.

What do yall think about the engije getting hotter at idle and up hills though?
 
MrBClark said:
Wouldn't it throw a code for those?
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Rarely, the computer has a difficult time knowing when an O2 sensor is lying or telling the truth. My TJ came with random O2 error codes and misfires but the previous owner already tried unsuccessfully to fix them with all new NTK O2 sensors which didn't fix it. The O2 sensor codes were ultimately cured by replacing the cats. That just illustrates the computer is pretty weak at figuring out what's wrong in the air/fuel ratio area.

I'm thinking the aroma you're smelling is fuel which is a classic symptom of a full-rich mixture... a classic symptom of a bad O2 sensor erroneously and continually telling the computer the ratio is too lean. The computer keeps richening the mixture to no avail until the fuel mixture is as rich as it can make it.
 
Jerry Bransford said:
Rarely, the computer has a difficult time knowing when an O2 sensor is lying or telling the truth. My TJ came with random O2 error codes and misfires but the previous owner already tried unsuccessfully to fix them with all new NTK O2 sensors which didn't fix it. The O2 sensor codes were ultimately cured by replacing the cats. That just illustrates the computer is pretty weak at figuring out what's wrong in the air/fuel ratio area.

I'm thinking the aroma you're smelling is fuel which is a classic symptom of a full-rich mixture... a classic symptom of a bad O2 sensor erroneously and continually telling the computer the ratio is too lean. The computer keeps richening the mixture to no avail until the fuel mixture is as rich as it can make it.
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Ok. I will take a look at that. How hard is it to change the upstream o2 sensors? I have the stupid 3 cats
 
I'd have to agree with Jerry on this. An engine can run with bad O2 sensors for years (my last truck was close to a decade without a code) I had thought it just got shit milage. O2 change out can be anything from easy as can be to a demonic nightmare worse than a Mother-in-law! 👹
 
I think you have several issues here. The overheating is possibly a failing radiator or fan clutch. Have you ever overhauled your cooling system? I had a problem with my Cherokee where it'd overheat going uphill and at idle; turned out to be a bad water pump, of all things.

Agree with the others about the O2 sensors, though you might also check for a valve cover leak. I had a smell going uphill occasionally, but the culprit was my leaky valve cover dripping on the exhaust.
 
bromel said:
I think you have several issues here. The overheating is possibly a failing radiator or fan clutch. Have you ever overhauled your cooling system? I had a problem with my Cherokee where it'd overheat going uphill and at idle; turned out to be a bad water pump, of all things.

Agree with the others about the O2 sensors, though you might also check for a valve cover leak. I had a smell going uphill occasionally, but the culprit was my leaky valve cover dripping on the exhaust.
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Unfortunately I agree with the "several issues" statement. Probably going to start looking into replacing the water pump. The radiator was replaced before I bought the Jeep.
 
MrBClark said:
The radiator was replaced before I bought the Jeep.
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Replaced with what? Unfortunately the aftermarket radiators are notoriously unreliable. Mopar is best. But I'd recommend replacing the thermostat and water pump in that order before you bite the bullet on a new radiator. Might be the fan clutch, although since you are getting hot at speed that likely isn't the problem.

You have an 01, so you have to be aware of the 0331 cylinder head issues. Are you losing coolant? Cracked head can lead to overheating, but let's hope that isn't the problem.
 
bromel said:
Replaced with what? Unfortunately the aftermarket radiators are notoriously unreliable. Mopar is best. But I'd recommend replacing the thermostat and water pump in that order before you bite the bullet on a new radiator. Might be the fan clutch, although since you are getting hot at speed that likely isn't the problem.

You have an 01, so you have to be aware of the 0331 cylinder head issues. Are you losing coolant? Cracked head can lead to overheating, but let's hope that isn't the problem.
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My Jeep is on its 3rd cylinder head. The previous owner replaced it once with another shit one and i had to put a tupy head on it. The radiator was a Mopar replacement.
 
Oh wow. Actually I remember you posting about your cylinder head saga end of last year. Well that's good to hear about the mopar radiator. My vote is on water pump causing your issues.
 
bromel said:
Oh wow. Actually I remember you posting about your cylinder head saga end of last year. Well that's good to hear about the mopar radiator. My vote is on water pump causing your issues.
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Yea. Still wish I didn't settle for an 01 with the bad cylinder heads. Lot of money to fix and not. I will definitely start with the water pump and hope it fixes my issues. Then I gotta look into the 02 sensors.... this jeep is a money pit.
 
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