2021 challenger 6.4 barely runs. help

[John9754]

the car has longtubes, hellcat injectors, E85 and a tune. this just stared when I tried to drive it today. It barely runs, is dying and jerking. log attached.7-08-25.hpl

[fumanchu182]

After reviewing your log you seem to have some sort of electrical gremlin. Your Pratio just drops off and your fuel system goes into an unknown state. Then certain channels just drop off and go bonkers. Please do a physical exam of the vehicle, make sure sensors are plugged in. Make sure nothing has melted on the headers, etc. Also please attach your current tune.

[John9754]

Has codes P1DF3 and U1428. makes sense I guess. tune Attached.

[Spray-Cam Hell-Ram]

Small chance that your pcm could be failing. But the more likely issue here will be either a wire, pin, or connection issue at your 8-wire transmission plug (Assuming you have an 8-speed trans) or a failing TCM. More often than not its an issue with the 8-wire trans plug that connects through the mechatronic sleeve.

[DodgeBoy_8HP]

I am inclined to believe that Spray-Cam Hell-Ram is correct.

John9754, did you change anything on PCM? Harness changes?

[John9754]

No changes.

[Spray-Cam Hell-Ram]

If you haven't already, jack the car up and put the rear on stands or up on a lift (not sure what you have access to), start the car and have someone or yourself go under the car and get to where you can grab the transmission's electrical connector that locks in through the mechatronic sleeve there on the passenger side about 2/3 of the way towards the rear of the trans (if auto 8 speed) and make sure the plug lock is locked all the way counterclockwise and the plug fully inserted into the sleeve. And if it appears to be, gently grab the harness an inch or two behind the connector plug that twist locks and lightly shake the harness and see if you hear any chimes from your dash while doing so. If you do, the problem is one or more of the pins or wires just before the pins. If this test passes, grab onto the back of the twist lock portion of the plug and push the plug inward as if trying to push the plug further into the sleeve with a good amount of force and see if there are any noticeable changes or chimes coming from the dash. If it changes or chimes, your mechatronic sleeve either isn't locked into the tcm all the way or the mechatronic sleeve has failed physically. If this test passes, bring the car back down and shut it off and put the ignition into run but don't start it. Locate your Canbus C (Dash) star connector. Not sure where it is in the challengers but in the 4th gen Ram trucks it is located in the front passenger kick panel near the side wall about midway up between the floor board and the dash. There are 4 or so of these connectors in total. On the Ram 3 of them are located tucked away on the left side of the steering column just behind the panel directly below the steering wheel and the canbus C star connector is solo on the passenger side as described above. The canbus C (Dash) Star connector is the smallest of the 4 containing just 6 total of the 2 or 3 wire plug-in junctions on a single strip, but are the canbus circuit "home runs"/ junctions for the 6 most important ecms/modules of all. Each plug in represents a module. On this star connector you've got the TCM, ABS module, Power Steering module, Drive train Control Module, PCM, and then a direct connection over to one of the star connectors on the driver's side ( Canbus C (Instrument Cluster Panel) Star connector). Make sure all 6 are seated all the way and that all the wires going into the back of the plug-ins are pushed in all the way or the wires aren't broken just before going into the plug-in (most common issues). Also get a meter and read dc voltage across each wire going into each plug with the other meter lead on the single ground wire on the star connector. Its the only black wire and only 1 of the 6 plug-ins will have 3-wires and that extra wire being the single ground. You should read with ignition in run position right around 2.5 volts on each wire. If you come across one that reads less than 2.15 volts DC , start unplugging the plug-ins one at a time until your voltage reading that was low, shoots back up closer to 2.4 or 2.5 volts DC. Whichever module you unplugged that brought the voltage up contains a fault either in the wiring to that module or a fault within the module. I have taken the time to explain all of this for 2 reasons. First, because of the CEL codes you listed as showing up currently. If its for some reason not tcm related, this star connector is where I would go next. If this star connector checks out, then Id go to the Canbus C (Instrument Panel) star connector next.  Secondly, so that this post is here on the forum if anyone in the future searches issues with certain codes and/or canbus circuit issues/canbus codes/communication codes and needs to try and troubleshoot to find their issue. 

[John9754]

Thanks a lot. Sounds like real good information.

[Spray-Cam Hell-Ram]

Hope it helps. Let me know what you figure out...

[bada44]

Holy cow, I have a 2005 Dodge ram was running perfect. I got fuel one day in about 4 hours later my truck started bucking RPM surging, the log and my wide band was reading lean while the computer was trying to pull fuel as if it was rich. I changed out cam sensor, crank sensor, O2 sensors, air temperature sensor, map sensor ,throttle body unplugged every connector you can possibly get to. remove the computer plugged it back in no burnt wires I am running an 8-speed using sound German controller for the transmission and a custom fuel system. And in the end I decided to hunt for a new PCM and found a manual transmission computer which I now have installed and now I have a whole new set of problems trying to tune this PCM as it does not like any of the data that I was using in the factory PCM that was in my truck I have another post you could see it for what I am running. 2005 Dodge ram I do not believe has any of the can bus stuff but the problem described here sounds an awful lot like what I encountered.