Undiagnosed low power/torque


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Old 06-11-2019, 10:45 PM   #1
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Default Undiagnosed low power/torque

Hey guys,

New to the forum, excited to see if I can get some help finally. 5 mechanics now and no diagnosis.

2004 Jeep wj 4.0 150k:

Jeep has weird issue where I have no power in high torque situations. Basically If I completely stop on a steep enough grade "especially in reverse" I can put my pedal to the floor and go absolutely no where. Jeep will hover at around 2000 RPM but will typically not peel out or move. With any sort of momentum you would never even notice the problem. Engine sounds fine while all this is happening. It just feels like your doing a brake stand.

Also trans has overheated a couple times when cruising some grades on logging roads. Also seems to shift kinda goofy when on steep grades going at lower speeds.

No its not fuel filter/air filter/spark plugs....checked all the basics


I have changed all brake components in the front and rear seems fine. Chopped off cat and exhaust today and it didn't help. All the mechanics and trans shop I took it too couldn't find anything. Fluids look good. IDK where to go from here. hoping for some suggetions and or help

thinking of a tranny flush and 02 sensors next but no codes being read.


- THANKS!!!!
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Old 06-12-2019, 10:48 AM   #2
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Any check engine lights?
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Old 06-12-2019, 07:15 PM   #3
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No check engine light


I should mention the other day I had a small fire near the top of the oil pan below the exhaust manifold.....but it was super hot out and I was driving slow up a steep logging grade....

the idea was pitched to me that maybe the bad cat was causing the exhaust manifold to get hot and that's what started the fire and my low torque problems in the first place

but its def not the cat or exhaust (tested this)

Also I have smelt what I thought was oil burning when driving in similar situations but could be the tranny getting hot maybe too? I just say that cuz it has overheated a few times.....
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Old 06-12-2019, 07:25 PM   #4
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Try adjusting your TV cable. may not let the tranny shift properly.

Get one of these: ELM 327 OBD II Bluetooth scanner And the app called torque Pro. This will let you scan the vehicle and monitor the engine sensors. You can check your TPS to make sure the ECM is actually getting a 90%+ command from the throttle pedal. Plus you can clear codes and monitor a whole bunch of other sensors.
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Old 06-12-2019, 07:45 PM   #5
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Sweet thanks for the tips! Ill order up that scanner since its so cheap and try messing around with the the cable tomorrow since that seems like an easy place to start as well.

But I will say Im not thinking ill get a lot out of the adjustment just because the jeep is shifting fine really. The only time it shifts goofy is when driving slow up steep logging grades.


Also I have had scanned a few times now with no codes being thrown...but ill def get that tool you mentioned so I can check out ECM and relationship
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Old 06-12-2019, 08:39 PM   #6
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You didn't say when the last time the tranny oil and filter was changed. Make sure the tranny is hot and in park and on level ground when checking. Check all your vacuum lines for leaks. you can spray carb cleaner around the engine, intake and vacuum lines to see if the engine revs, if it does, you have a vacuum leak. But be careful you don't get spray on the exhaust.

BTW Torque Pro does way more that just read codes. You'll love it once you get it.
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Old 06-14-2019, 03:36 PM   #7
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Sweet yeah just ordered Torque Pro

Trans fluid looks good, but actually does seem a little overfilled

I plan on just getting the thing flushed either way I think

Ill give the vacuum leak check a try as well thanks!
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Old 06-14-2019, 06:06 PM   #8
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I wouldn't even know how to diagnose this but ,could it possibly be a mechanical bind? You say with any kind of momentum it's not really noticeable. Have you opened your differential covers to check the oil in your axle and gears? How's the fluid in your transfer case?....just spitballin'....by your descripsion, angle and lack of momentum cause the issue ,correct?
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Old 06-14-2019, 06:10 PM   #9
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What 4x4 system do you have? Select-trac,command -trac....ect.
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Old 06-14-2019, 06:39 PM   #10
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Another thing to try next time it happens. Try manually shifting into 1st gear with the shifter. After thinking about it you may have a solenoid in your transmission going bad. Had it happened in my 4L Grand Cherokee wife thought the transmission was slipping she would come to a stop sign. Press the gas and vehicle would take off very slowly like the transmission was slipping. In reality it was never down shifting into first gear. If you would down shift it into first gear vehicle would take off. And return the stick to D
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Old 06-16-2019, 05:26 PM   #11
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WJLIZARD,

its not the angle per say, more so just a high torque situation. The problem is even noticeable on level ground say try to wheel a big bump or something before the car is on an angle....

I believe the tcase is selec trac? Its got the 4 full and part time with 4 lo

Checked a bunch of fluids today, heres what I saw


Tcase- Looked good, full decent color

Rear Diff- Full decent color


Front Diff- Full but dark (needs to be changed)

Transmission- good color pinkish...but seems way overfilled to me....and lots of bubbles on the dipstick
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Old 06-16-2019, 05:29 PM   #12
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Also, I have tried taking it out of overdrive and dropping into first before with no benefit or effect...seems even worse in reverse maybe


Gluckmysock,

I still have to look for that vacuum leak
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Old 06-16-2019, 05:30 PM   #13
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could an overfilled tranny have some similar effects?
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Old 06-17-2019, 12:01 AM   #14
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Not sure what exact effect over filling a trans.would have but sure it's not beneficial. I would look into the flush you were talking about.
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