Recommended diagnostic tools for my power loss issues?

k0m0d067

TJ Enthusiast
Joined
Jun 9, 2019
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131
Location
Victoria Australia
So some of you may have read my dilemma...03 TJ 4.0 has power loss, and dies after running for about 5 to 10 minutes...not coughing/sputtering...just zero power, and dies, if you come to a stop/push in the clutch...starts again, reluctantly, after a few minutes, but the power is lacking...

In order to avoid simply throwing parts at it, and because I can't afford to take it to a shop (and prefer to do it myself, if I can just figure out what the problem is) I want to properly diagnose the cause...

I figure a fuel pressure tester, and a compression tester are good places to start...

Anything else come to mind? Should I look into an OBD reader? Or is the "turn the ignition to start 3 times" trick good enough? (Check engine light comes on every few months or so, then goes away after a few days, and currently not showing any codes)

Just had to walk a half hour in the rain, and while my fat a$$ can use the exercise, better weather would have been nice 😁
 
A Bluetooth OBDII reader and the Torque Pro app makes diagnosis easier, but is not necessary. The key trick will help you pull codes, but with the OBDII reader you can also look at other instrumentation in the engine, driveline, and exhaust system
 
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May be worth it to have a reputable garage diagnose the problems, and then from there you can fix it your self, or not. Those million dollar test computers can find most any issues. Even ones you dont know about.
 
So some of you may have read my dilemma...03 TJ 4.0 has power loss, and dies after running for about 5 to 10 minutes...not coughing/sputtering...just zero power, and dies, if you come to a stop/push in the clutch...starts again, reluctantly, after a few minutes, but the power is lacking...

In order to avoid simply throwing parts at it, and because I can't afford to take it to a shop (and prefer to do it myself, if I can just figure out what the problem is) I want to properly diagnose the cause...

I figure a fuel pressure tester, and a compression tester are good places to start...

Anything else come to mind? Should I look into an OBD reader? Or is the "turn the ignition to start 3 times" trick good enough? (Check engine light comes on every few months or so, then goes away after a few days, and currently not showing any codes)

Just had to walk a half hour in the rain, and while my fat a$$ can use the exercise, better weather would have been nice 😁
I have the same Jeep and the same problem. It was the Cats. When they're cold they'll produce enough back pressure to get moving (and fool testing equipment)... But as they warm up whatever's stuck in the honeycomb mesh expands and closes down the airflow (and your jeep's power). Oh, yeah, your O2 sensors are probably toast, or on their way to being toast.

In California, there's basically two cats you can replace them with... OEM's and Magnaflow. Ouch. That sucking sound is cash leaving my bank account.
 
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If your renting tools to do your own diagnostics, I would also rent an exhaust back pressure tester. Test before and after the cat converter to see if they are clogged.