Misfire

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Muddy

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Chiming in to say I'm currently chasing down what seems like the same problem in my 04 sport. Had o2 sensor codes on in the background for months, yesterday on the way home from town the truck suddenly has no power, CEL flashing on and off, bucking under partial throttle, and gas mileage goes way down. No other codes other than p0174 p0175 p0137 and p0138. O2 sensor voltages look weird on the OBD scanner app I have. Head gasket was replaced recently, coils are fairly new, no misfire codes but there was a definite misfire. I ordered 4 new NTK o2 sensors, I'll see if that fixes things.
 

Muddy

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Dunno if OP ever got his sorted out, but I did mine that was doing the same. Replaced all 4 O2 sensors, jeep ran great under 2k rpms now but still has no power. Turns out the passenger side catalytic converter was in pieces and clogged partially, no doubt damage caused by running with the misfire from the bad O2 sensor on that bank. Gutted the cats, she runs like new again.
 

JeepKJ_Guy

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@Muddy,

When I bought my 2003 Liberty Sport 3.7 V6 the O2 wires were just hanging unconnected to the O2 sensors, - about 8 months ago.

After I got 18 ECM codes down to 3, - now with 2 of them O2 sensors each rail - I replaced all coils and plugs, and TPS, PCV, and many other sensors around the throttle body, - she runs like a champ.

I speculated the wires to the O2 were yanked out by looking at them, and will just leave them alone - this V6 runs as fast as a V8 - a good friend couldn't believe the acceleration.

I'm curious too - what was the fix that the original poster made?

I was betting a injector, - you can get them all cleaned out at lots of places, I did my Z28 at Valvoline, about a 1/2 hour 45 min process of running a can of cleaner straight into the throttle body, - it runs real smooth and gained many horses!
 

ltd02

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I'd like to hear what the OP found too. I think the injector is a good possibility although it could just be worn out O2 sensors. Just had that on one of my vehicles. Unfortunately we have emissions testing around me so can't run around with O2 sensors disconnected. I have gutted a few catalytic converters over the years.
 

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