Hello All,
I got a 99 Ram 1500 5.9 that has been giving me hell ever since I got it a couple months ago. I recently installed the plenum kit from hughes along with the upstream o2 sensor, plugs, wires, cap, and rotor and the truck still runs like crap. I have CEL codes: P0132, P0135, P0302, P0138.. I used autozones scan tool and both up-downstream o2 sensors read 1volt steady with a warm running engine.. I replaced the plug wire for cylinder 2 and still no change. While driving the truck it misses hard especially in the low rpms (1-1.5 is really rough) Idle isnt great but it does hold pretty steady. PLEASE HELP!!!

 

Grab the 98-99 Service manual from here. Dig thru the wiring diagrams, and find out why the PCM thinks your O2's are shorted to voltage.....

Make sure your wires are ran per the TSB for plug wire routing. (in the faq section)

Disconnect the O2 sensors for the moment, and see if the truck runs any better.

How's your cat?

 

Plus one on the cat. Pull out that front o2 and see how she runs

 

Thanks for the quick posts guys! I thought that the o2s communicated directly with the pcm? I will dig into that a bit. As for the cat its an aftermarket unit (magnaflow/flowmaster I believe) and its not giving me a rotten egg smell or a rock in a can sound except for when I let up off the gas, which sounds more like it comes from the passenger side of the engine.. could be my loose exhaust shield. I will pull the o2 when im put of work and see how she reacts. I didn't replace the cat after replacing the plenum, you guys think that could cause the o2's to go haywire?

 

No, the O2's are more than likely an electrical problem.

 

Update: After removing the o2 sensor I went for a drive, the truck was more responsive but I still experienced shuttering/missing in the low rpm range (primarily in 4th gear) Also, I took a volt meter to the plug prongs and got a reading of approximately 4 volts on the o2 side, and a reading of .3 on the heater side (warm running engine) I checked the spark plugs as well and they still appear in new condition.

 

From a wiring diagram I found in my Hanes manual I was able to figure out the o2 sensors communicate with the PCM and the automatic shutdown relay. Any idea what this means? Am I looking at a faulty PCM?

 

NGK brand O2? Champion copper plugs gapped correctly. Routed the plug wires .

 

PCM gives O2 sensors five volt reference signal, sensor modifies the signal. PCM gets back 0-1 volt, .5 being 14.7:1 mixture ratio. (why you see it bouncing around as PCM changes mixture.) Heater just gets the O2 ready faster. Heater circuits are tied to ASD relay. Should see 12 volts on the heater circuit, if you don't, need to find out why.

Stuttering in fourth is a sure sign of an engine miss. My guess would be, your crank sensor is beginning to fail.

 

Oiiiii these codes are a royal PITA. P0132, P0135, P0138 are voltage issues, not fouled sensors. I know because I had them and new sensors did not fix the codes.

Get both O2 sensors replaced. Honestly if that doesnt fix it, you need a new PCM for your truck sorry to tell you.