Hi I have a 2001 Dodge ram 1500, 5.2L, 91,000 miles, with 5 speed manual transmission.

It sputters on idle when cold(with loud hiss from IAC valve), surges when releasing the clutch(only really bad when cold), hasnt got much power, and is only getting 9 mpg. I bought the truck from aunt, after cousin passed away, knowing it needed work. It had error codes for both o2 sensors and had the above problems. I have replaced Cap/Rotor, plugs+wires, coil, map sensor, IAC valve, TPS sensor, TB gasket, upstream and downstream O2 sensors, Catalytic converter, and have done the Hughes plenum repair. This has all been done over several months with little improvement to driveability. I read about driving with upstream o2 sensor unplugged, and when i did it i got code p0031 and p0132. Now p0132 is that the oxygen sensor has stayed at a high voltage for too long without switching back. I've looked for melted or cut wires, but dont see any. Has anybody had these issues? Is my ECM fried or do i have short in the harness somewhere?

 

Check compression.

Getting any misfire codes?

Ignore any O2 codes set when they are disconnected.

 

I dont have any check engine light. Do misfire codes require a professional code reader?

 

I borrowed a compression tester and im looking at 120-135 psi for all the cylinders

 

Yeah, need a code reader to pull codes.

Check engine light being off implies there aren't any though.

How's fuel pressure?

 

Forgot to mention i replaced fuel pump and assembly as well, but checked it again and its at 48-49 psi.

 

Is your temp gauge reasonably accurate?

Vacuum leak somewhere??

 

Temp gauge is good. The IAC makes a large vacuum noise, but if i unplug it, it stops and i dont hear any other vacuum noises. I've sprayed around all the vacuum lines and intake manifold but dont see or hear any leaks. Wen the IAC is plugged in and it's warm it doesn't make the loud vacuum noise anymore. I'm having trouble finding which wires run to the computer from the o2 sensor. Also, Rockauto showed the denso 234-4030 for the upstream, which is what i bought, but i haven't found anyone else mention using it. Maybe it has the wrong voltage to temperature range? Im beginning to suspect the ECM is screwed up on the upstream O2.

 

If it was *just* the O2 sensor, it would run fine for the first two minutes after cold start, and then start running like crap. Since it runs like crap right away, probably something else.... Is it missing bad? Running rough? Does it try and shake itself apart when you hit O/D?

 

It shakes bad at idle and surges when starting from a stop until its warmed up for a bit. If it sits for maybe an hour after warming it takes a little more cranking for it to start. If i accidentally let go of the starter to early and it doesnt have enough momentum to keep running, trying to start it takes a lot more cranks to fire. After warming up it idles fine and doesnt surge when starting from stop but doesnt seem to have much power. 5th gear especially has no power and will hardly hold any speed, even on flat ground.