Need help with codes.


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Apr 15, 2021
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So the 04 Libby 3.7 started running like **** and basically wouldn’t even move and had to be towed. Pulled a bunch of codes that led me to believe plugs/coils were done so I replaced all 6 and cleared the codes. Now when I start up it runs fine when it’s cold but as it starts to heat up it just starts to run worse and worse and once fully warm it can barely run at all. It’s throwing code p0172 now (bank 1 rich) and once it starts to run ****** you can unplug any of the coils on the drivers side and it doesn’t make any difference to how badly it runs and if I unplug a passenger side it will **** the engine. No obvious loose connections or vac leaks.


Nov 11, 2018
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It's probably a bad O2 on that side. After the engine warms up, the PCM goes into closed loop and starts reading the O2's info. If the info it's reading is bad, the PCM makes adjustment that make it run like ****. In your case, the O2 is probably incorrectly telling the PCM the fuel mixture on that bank is too rich, so the PCM in turn is en-leaning the mixture on that side too much to the point you're getting misfires- hence why you can pull the coil's power plugs there and not notice any difference in how the engine runs. Pull the O2 plug on that side and see if the problem goes away after warm up. It should force that bank to stay in open loop. Replace only with NTK brand.

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