Cheers everyone,

I am still having some trouble with my 2004 RAM 1500 5.7 HEMI 4x4.
Idle is very rough sometimes, and it sputters/hesitates when driving.
I had a P0300 at some point, but that hasn't come back though after I replaced some wiring though.
Now my next guess are one or more O2 sensors.
I now have a Diablosport Predator that is functioning quite well despite its age.
I hooked it up and viewed the live data from the O2 sensors, but have no idea what these value mean:
O2S 11 DEF - 2.61 Volts
O2S 11 GOAL - changes from 2.61 at idle to 2.33 - 2.45 when driving
O2S 12 ADAP - 0.00V
O2S 12 GOAL - 2.75V

I also checked sensor 21, values are:
O2S 21 DEF - 2.61 V
O2S 21 GOAL - changes from 2.61 at idle to 2.20 - 2.57 when driving

Are these "normal" values?
Or isn't that effective to test the sensors?

Thanks for any help guys!
It is really driving me nuts and I haven't found what's wrong for over a year now

 

No. Those aren't normal. I am surprised they aren't setting codes. Values should bounce between 0 and 1 volt...... What do short term and long term fuel trims look like?

 

I watched a video on YT, that guy was using an original DRB III scanner though: (Beginning at 12:12)
He explains something there that Chrysler is using a voltage divider for the O2 sensors so the reading won't be like 0...1 Volts.
But I also don't know what these values mean and if these are the real voltages measured?

Oh, fuel trims:
bank 2 is fine I think, fluctuates a bit but all below 4 or 5%
bank 1 is fine too most of the time, but if it starts running bad short term goes to +20/+25%.

 

I would be tempted to unplug the front O2 sensors, and go for a drive. Yes, that WILL set a code, and the engine will NOT go into closed loop, but, if it runs better that way..... you can be fairly confident the O2 sensors are the culprit.

 

I will try that for sure, but that won't tell me which sensor is bad, will it?

Another thing will be to check the injector control with an oscilloscope maybe.

The problem is only intermittend, goes away on its own. When it is idling rough it will do it for 2-3 seconds then get back to "normal" etc. Very odd. Maybe some loose contact or broken/damaged wire?

 

Or a failing sensor.... For O2 sensors, if you have two "sensor 1", (bank 1, and bank 2) they both live in the exact same environment, so, if one of them is failing, chances are very good that the other one ain't far behind. That, and sensor performance does indeed degrade over time, so, having an old sensor, paired with a new one, can introduce issues all it's own.

 

I have no experience with failing O2 sensors though. For me it would be like "it is working" or "it is not working" though.
Or can there be like an internal damage to the sensor that might not be present all the time and is only there for a few seconds?

Will unplug the upstream sensors first and test though. Seems like the easiest task?!
Strange thing is, that it has been doing the same for 14.000 miles now.
Truck now has 140k miles on it.

What I forgot: when I am driving and it starts to run bad, especially at lower RPMs (around 1500) and I apply a little bit more throttle (to accelerate and not hold speed), it will get really "shaky" and building up. So that seems to me like the control circuit is too slow to react to the changes. Would that be a typical error of a old/slow O2 sensor?!

 

Yeah, O2 sensors have a selection of failure modes that WON'T set a code.... They can be slow to react, or, just inaccurate, and the PCM won't know any better..... It just tries to run the motor on the data it gets.... If the data is wrong, then it doesn't run well.

Try the test, see what happens. Take it from there.

 

I see, I see. Will do the tests and then decide what to do.
Thanks so much for your help!
I'm no car technician so rely on the help I get here!
I'm sure we will get this running like it should!