Then engine itself really can't do anything with backpressure to make the throttle harder to push. I would be lookin' real hard at the TPS though.

 

The current one seems to give accurate readings when I monitor with my scan tool, but I really wonder if it periodically acts up and sends poor readouts and messes up the PCM. And maybe it is somehow putting resistance on the throttle valve? I'm not sure how, but I think I will go ahead and order a new TPS regardless. Is OEM definitely the way to go, or is aftermarket serviceable in this case? It looks like I can get a Delphi part for about $45 on RockAuto.com. Not sure how much Dodge wants for the OEM sensor.

Incidentally, I had to travel out of town today to pick up a couch, so out of curiosity, I filled up with 93 octane this morning and used my Superchips Cortex tuner to install a performance 91+ octane tune. I had purchased the tuner for use in my '08 Hemi Ram, but I didn't like the way it ran with the tune, so I've never really used it. I thought I'd give it a shot with the old '01, and WOW, was I surprised at what a difference it made. It ran better on the highway today than it has in years. The throttle response was immediate, and it seemed like the engine and transmission were finally on the same page. There were still a few instances where I noticed it ran a little more sluggishly, but the symptoms were not nearly as noticeable as they normally are. I also noticed my pre-cat O2 sensor readout seemed to be consistently 0.6V and above...not sure if that is normal at highway cruising speed, but my understanding is that ideally the voltage should constantly "cross over" above and below 0.45V. Is that correct?

 

I don't know how much the OEM sensors are.... but, I would suspect that here is some possible internal failure in the TPS, and it occasionally 'binds up'.... at which point, it is sending wrong signals to the PCM, and you end up with the engine running weird.

Yeah, Ideally, the O2 should bounce around, but, it's possible the PCM is still learning with the new tune, and is running a tad rich. Is it actually in closed loop?

The new tune probably greatly reduced torque management....... not sure what chrysler was thinkin' with that one..... unless it was solely to make up for their crappy transmissions.

 

That's what I wondered, if it was binding somehow. I'll get a new one on order. I've been hesitant to just start throwing parts at this gremlin, but eventually I've got to start somewhere, and this seems like the most logical, and most inexpensive, place to start. Thanks for your input.

Yeah, it is definitely in closed loop (at least, according to my scan tool). I'll keep an eye on the O2 readouts this week to see if the behavior changes. So far, I've driven about 120 miles since I installed the new tune.

Yeah, I've always heard about how much the torque management neutered the engine. I guess today was the first time I'd ever felt what it was like to drive "unleashed". It was refreshing. I'll be keeping this tune installed for sure. And I bet you're right - the torque management system was probably the "fix" for the soft transmissions. That's a shame.

Thanks again for all of your help. I really appreciate it.

 

Just out of idle curiosity, how old are your O2 sensors?

 

They're old :-) As in, probably never been changed old. I'll have to check my maintenance log, but I've owned the truck since '05 and don't recall them being changed. That's been on my to-do list, too....particularly since my plenum gasket was bad for probably a very long time. I tried pulling the pre-cat sensor a while back but it was stuck pretty good and I lost patience and gave up. I'll have to give it a bath in PB'laster and have another go at it soon.

 

Good Idea.

 

There have been some new developments today. After some encouraging results following the installation of the Superchips 93 octane tune, the truck has been running especially poorly the past few days...so poorly that this morning I used my scan tool to check for pending faults. There were none, but the truck felt like I was trying to pull a weighed-down trailer. The engine seemed to be struggling, and the transmission shift points were acting very strangely. It remained this way all day, and then on my way home from work just now the check engine light came on with the P0420 code - catalyst system efficiency below threshold.

So, in a way, I'm glad to actually have a code that may eventually lead me to the source of my incessant issue. But, what should I do next? Should I replace both O2 sensors first and see if that solves the problem? I checked my maintenance log and the sensors were replaced almost 120,000 miles ago, so they are overdue. I think I also noted in a recent post that the upstream O2 sensor voltage seemed to be hovering around 0.7V or 0.8V consistently. The engine also seems to possibly have a slight miss...so possibly it has been running too rich (uncombusted fuel), which has finally destroyed the catalytic converter? If that's the case, I need to figure out why I have a miss...maybe I should check the spark plug wire routing.

Or, would it make more sense that the cat is simply shot/clogged, and that is most likely the entire issue all by itself.

What should my next step be?

Thanks in advance for any advice anyone can offer.

 

Remove the front O2 sensor from the exhaust pipe completely. (it leaves a nice hole) Go for a drive. (you will most likely get codes.) If it runs better, cat is clogged.

 

Use a Vacuum /pressure Gauge and Test it to see if it has back pressure. Then you will know if it is plugged or not.

Example: