Sorry, I have had no updates, life has gotten in the way. Unfortunately, I threw away the fuel rail, I am checking with some local salvage yards if anyone has a 3rd gen dodge to go get one.

 

Well, it is almost 2 o’clock in the morning and I’ve been working on this truck since I got home nine hours ago. I was able to buy plugs for the O2 holes for when I removed the O2 sensors. I pulled the O2 sensors out and let them hang and drove the vehicle around. I put thermalcouples on the muffler pipe before an after the catalytic converter. While driving B1, S1 was ranging around 0.12 to 0.28 V and B1S2 was between 0.14 and 0.22. The system was running in closed loop for a while, but after it threw P0132 and P0138 ( 02 sensor high voltage B1S1, O2 sensor high voltage B1S2, Respectively ) it never returned to close loop operation, it either stayed in N/A or open loop operation.
I filled up the tank, cleared out the codes and the P0132 code came back immediately as well as pending codes P0303 (cylinder three misfire) and P0138. I tried to hold the idle at 2000 RPM‘s so that I could monitor the temperature of the catalytic converter, but it was much too difficult as the engine was revving up and down on its own. I did manage to get an upstream temperature of 326°C ( 618°F ) and a downstream temperature of 372°C ( 701°F ).

What is very interesting, is that while sitting in the driveway trying to rev the engine add 2000 RPMs, I also received a P0500 code “vehicle speed sensor A”. I cleared the codes again and P0132 came back immediately, and I had pending codes of P0500 as well as P0303. After running the vehicle a while, which was very difficult since the whole engine was shaking as if it was unbalanced, I cleared the codes another time and did not get any immediate codes, but the pending codes were P0303 as well as P0171 (System too lean!!!!!). Somehow miraculously within several hours I went from having a P0172 to a pending P0171

I did check the connection of the coil on plug on cylinder number three and all seems to be well. I did not pull the spark plug out as it’s almost 2 o’clock in the morning.

I think, I can rule out the catalytic converter, because it mostly maintains at least 46°C ( 118°F ) delta between the inlet and the outlet, the outlet being hotter ( it is the original catalytic converter with 270,000 miles on it )


As it stands, the engine keeps quitting if I try to leave it in idling as the idle seems to be hunting. If I turn the truck off and turn it right back on it seems to idle fine again until I touch the gas pedal.

The upstream O2 sensor is much cleaner than the downstream O2 sensor. These are OEM sensors with less than 6000 miles on them. Yes the threads on the downstream O2 sensor look buggered up, because they are. It looks like the mechanic who installed the O2 sensor at the dealership cross threaded it. I have no idea how I’m going to secure the downstream sensor once I put it back in again. I may have to have a collar welded in.

One additional piece of information, the exhaust really stinks now.

 

I removed the O2 plugs, reinstalled the O2 sensors and was shocked that the upstream plug was covered with carbon and the downstream plug was clean. Obviously the catalytic converter scrubbed the carbon out of the exhaust gas.

I drove 100 miles non stop and had two pending codes P1195 (O2 1/1 Slow response) and back to the original P0172. The big difference now is that once I touch the accelerator even once, the engine idles around 2200 rpms. I can drive down the road at 35 mph without touching the accelerator. Once I turn the truck off and back on, the idle returns to normal around 650 rpms to 700 rpms. With this, I took advantage of this and measured the temperature of the catalytic converter and noticed that I am only getting about 30°F difference between inlet and outlet (I wonder if driving without the O2 sensor and sending all the carbon may have finished an already dying catalytic converter).



I was able to get some excellent data with the engine revving at 2200 rpms

675°F inlet of catalytic converter

696°F outlet of catalytic converter

21°F delta temperature across catalytic converter

Closed Loop Fuel System status

13% Calculated Load

-31.3% Short Term Fuel Trim B1

-33.6% Long term Fuel Trim B1

5 PSI Intake MAP

2289 rpm Engine speed

0 mph Vehicle speed

41° Ignition timing

103°F Intake air temperature

22.4 % Throttle Position

0.740 V O2 B1S1

0.440 V O2 B1S2

-32.8 % O2 B1S1 STF

99.2% O2 B1S2 STF



I did notice that the downstream O2 sensor is definitely behaving differently, almost like the upstream sensor, like hunting.






Downstream O2 plug on top Upstream O2 plug on bottom

 

Replace the O2 sensor B1/S1. The PCM thinks it's running rich..... That may be due to a bad O2 sensor, or, you may have a leaking injector.

 

all that happened when I took the O2 sensors out and drove it with the O2 sensors just hanging there. I do believe the PCM thought the vehicles running rich because it was running rich without the O2 sensors, I pulled the spark plugs out after I put the O2 sensors back in and the spark plugs confirmed that I was running way too rich. I do believe the rich factor was caused by lack of O2 sensors being in the exhaust pipe. I failed to mention that the P0303 code went away once I did put the O2 sensors back in. I did pull the spark plugs out and inspected them and they were full of carbon. They may have been causing the misfire in cylinder three.

HeyYou, if you really believe that I should change the O2 sensor I will change it again but this is the second set of OEM O2 sensors that I’ve had on the truck in the last 3 months. I tried the Bosch sensors, then changed both again to the OEM sensors and after it threw a solid P1195, I changed both O2 sensors again with OEM from the dealer.


since putting the O2 sensors back in the only code I am receiving today is a P0172 code again AND the engine revving at 2200 rpms.

I did wire brush the spark plugs clean after pulling them out.


what do you think about the 21°F delta temperature across the catalytic converter? What do you think about the 675°F and 696°F temperature on the catalytic converter, does that seem too high?

I did buy the fuel injectors from rock auto earlier this year I don’t know if they under warranty but I can order new ones. Any particular brand that you favor?

 

Wow, that thing is running pig-rich. That is certainly not from just running without O2 sensors, something else is going on there. Fuel pressure is too high, or your injectors are leaking fuel.

 

Getting a lot of posts on this problem, I'm kinda losing awareness so I apologize if I ask a question that has already been answered.
Regarding your O2 sensors, you can clean up those threads with a die. I believe yours is 18mm x 1.5. There is also a thread chaser for the exhaust bung. Auto parts store may have these as a loaner.
For running rich, make sure your air filter is clean.
You put in new fuel injectors, what brand did you use? Injectors come programmed with a minimum pulse width and yours may be too rich for your engine. This would mostly be a problem at idle.
Your cat temps are not terrible in that outlet is hotter than inlet. You'd like to see a 100 degree warmer outlet. Your temps are high though, and I suspect this is due to unburned fuel in the exhaust. I think the problem is in the negative fuel trim numbers.
Let's get info on your fuel injectors and go from there. Perhaps contact the fuel injector manufacturer and ask if they can offer some trouble shooting info. You could send a copy of your live data to them for review.

 

WOW FINALLY!!!!
I finally received the new fuel injectors and got them in. The truck is idling normal again and does not quit running by itself. I am still running hot (700 degrees) on the CAT. I think the performance of the CAT may be degraded from running 9 months of running rich and dumping unburnt fuel in the exhaust. I will keep an eye on the CAT temperatures and I may have to resolve to replace it if the temperature stays at 700 degrees F. Does anyone know about what temperature I should see before and after the CAT?
Also, does anyone know a website or anything to get mode 6 code interpretations? I have googled it, but I have not had any luck with googling the mode 6 codes.

My Sincere thanks to HeyYou and jrsick for all the help!!!!