As always, thanks HeyYou! You had mentioned this trick before, and I just haven't been able to get my pre-cat O2 sensor out yet. I tried again today for a long time, spraying plenty of PB Blaster on the threads. I even started the truck and let the exhaust get hot a couple of times and then re-applied the PB Blaster, but no luck so far. I guess that's what I get for letting 120,000 miles pass by since I last swapped the sensors.

It is cold and rainy here, and with no garage or carport to work under, I think I am going to have to admit defeat and just take the truck to an exhaust shop. I have a feeling the cat is clogged anyway, so I feel that ultimately it's going to need to be replaced regardless. If I need to drop a few hundred bucks to get the truck to run well all the time, it will be money well spent in, in my opinion.

I may try again one more time tomorrow if the weather improves. Either way, I'll report back here when I have some kind of update/results.

Thanks again.

 

That is a fantastic idea! Why didn't I think of that? Thanks! If I can get the O2 sensor removed, I will give this a try. So far, the sensor is kicking my butt, though. As much as I hate paying someone to do something I feel I should be able to do on my own, I have little spare time and the weather has been lousy, so I am close to just having a shop check it out.

 

The exhaust shop can drill a tiny hole, insert the gauge, start the engine, and immediately tell you if your cat is clogged. If it isn't, they can just weld the hole shut, and you are done. Save you having to work outside in the crappy weather, and shouldn't cost more than a half-hour labor.

 

Great point. I will hopefully be dropping off my truck at a local exhaust shop tomorrow after work. I'll check back here with an update once I get a report back from the shop.

Thanks again for your input!

 

I have been expirencing a simular issue with my 1996 Ram 1500 5.2L i have replaced the computer and all my sensors except the O2 sensors. I did just replace my cataletic converter. it has gotten better than it was when it startedbut it is still not 100% one new symptom that has appeared is my heater controls will not move off defroster. acts like a vacume leak. going to check brake booster for rust/leak tomorrow.

 

The cats where recalled on 96's due to breakage of the honeycomb. Mine was so bad you had to yell over the nose at a drive threw. Got sick of it and replaced it with a magnaflow and two new NTK 02's. The heater issue you are having is a vac problem. Check the vac line going in to the cab.

This is what mine looked like when i cut it open.

 

Well, I have some progress to report. About a month ago I had an exhaust shop check the catalytic converter following the P0420 code. They said the cat was not plugged, and since this is the second shop to tell me that in the past several months, I tend to believe it. So, I then asked for an estimate to replace both O2 sensors, since I had been unable to break them loose on my own. They quoted something like $300, which seemed outrageous, but when I asked why so high, it turned out most of that was the cost of the parts. The labor charge was minimal. I asked if I could supply my own parts and have them install them, and they said no problem. So, that is what I will be doing. I ordered the sensors from Rock Auto for much cheaper and will have them installed soon, hopefully.

On top of that, I also changed my throttle position sensor this past weekend, and that seems to have had a significant impact on the performance of the engine. I have only driven it once since replacing the sensor - I had a transmission scare on my test drive and I have had the truck parked since (huge surge in RPM at near WOT - I have detailed that in another thread if anyone is interested) - but it had much more pep and the throttle response was much quicker. So, I have a feeling the TPS was the main culprit, but I still plan to have the O2 sensors replaced soon for good measure.

As for the P0420 code, it has come and gone multiple times over the past month. I deleted the 91 octane tune and switched to an 87 octane performance tune, and the code came back temporarily and then cleared itself. I have gone back to the stock tune for now following my transmission scare, and provided everything checks out with my transmission and I start driving the truck regularly again soon, I will see if the P0420 code comes back. I'll also keep an eye on fuel economy and will try to report back. Granted, the fuel economy comparison won't necessarily be apples to apples because we're coming out of an intensely cold winter (which seems to impact fuel economy with longer warmup times and higher idle at startup), and the winter blend gas may start getting phased out soon, but nevertheless, I'll see what the data says.

I'll update here again soon hopefully. Thanks to everyone that has chimed in to help me out. I really appreciate it.