TJ Suddenly Stalling

M

mbloom

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Joined
Dec 24, 2016
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19
Location
New Jersey
I was driving my 1999 TJ (6 cyl/ manual / 180K miles) and after about 30 minutes experienced no power in 5th gear with all other gears OK. Jeep had been running fine up until that point. As it was going to the shop for an odd brake issue, I asked mechanic to take a look. I had searched the forums prior and saw many posts about a clogged catalytic converter. Mechanic noticed the same issue with 5th gear (scanned, no codes), but said a clogged catalytic converter would cause the issue in all gears. He suspected the clutch, which I doubt. Drove it home and no issue, hasn't reoccurred in a few days.

Drove it the next day and the Jeep wanted to stall in lower gears. I put Sea Foam in the tank and changed the air filter (a tune-up was done less than a year ago plugs/wires/distributor.) The problem continued — in the first 5-10 minutes of driving the car wants to stall out both while driving and while warming up. I again searched for solution and noticed cleaning the IAC was recommended and that there could be a problem with the O2 sensors. No check engine light.

I am trying to attack this in the proper order and looking for some guidance based on the symptoms of where to start first — IAM, O2 sensor, clogged cat.. other?

Thanks!
 
You could test the cat by disconnecting the 2 bolts that connect the exhaust manifold to the exhaust pipe.
Disconnect the pipe and start the engine. If it runs fine, you have a bad cat.
Any idea if it's the original cat?
 
KCsTJ said:
You could test the cat by disconnecting the 2 bolts that connect the exhaust manifold to the exhaust pipe.
Disconnect the pipe and start the engine. If it runs fine, you have a bad cat.
Any idea if it's the original cat?
Click to expand...

Thanks. I have only had the Jeep for about 18 months so do not know age of Cat.
 
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I just changed the “idle air control valve” on my 00 4.0L for about $70, I’m not sure if this is what’s wrong with yours but it could be an issue. Mine would run rough and really have no power almost stall out at higher speeds


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Jeep has been running fine for past few weeks. I suspect some electronic component will reveal itself in time.
 
I eventually got a code for the downstream O2 sensor. I was able to get it replaced. I spent 6 hours under the Jeep with a torch and couldn't get it to budge. Took it to a shop and they got it off with minimal effort (want to believe I loosened it for them). Was running the same (crappy) on ride back from shop, but later in day and next day it ran like a champ...guessing the onboard computer had to re-calibrate.
 
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Jeep was fine for a few days...then it wasn't...then it was. Not sure if the ECU has to re-calibrate, but assumed it did when I didn't experience any bucking for two weeks. It returned for a week then was gone again...grrrr.
 
Could it be bad gas or water in your tank maybe? Try buying gas from a different station for a while see if it comes back. It kind of sounds like it could be a symptom of bad gas.

Usually if it was caused by the PCM it would normally throw a code. Since it is not, my guess is it is something underlying like carbon tracks in the distributor cap. Maybe bad wires? or bad gas? What you are describing sounds like a basic underlying issue.

Check the basics
 
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