Alright guys Ive had it!! I have been on this forum for about 6 months now with a fairly common problem, but now im am stuck! Here we go....
2006 Ram 2500 5.7L 4WD with almost 40K miles. A few months ago it began to idle erratically. And now it idles at 0! Thats right the tach reads 0 PRM at idle. Does not stall though. On the highway at around 70 my RPMS sit around 300. Never had any codes just horrible gas mileage!
Now I will list, in order, what i have done to fix this problem:
clean throttle body, reset PCM, replaced PCV, reset PCM, seafoam treatment, checked vacuum hoses, cleaned throttle body (2nd time just because i was getting mad), reset PCM, went over every inch of the engine to look for any visible damage to any component, reset PCM, replaced MAP sensor, replaced both pre-cat 02 sensors, reset PCM. Took it to dealership for possible flash updates with no success. Also I threw in some fuel injector cleaner in the gas tank somewhere in all that mess!
Now all this was spread out over a few months and today ye olde check engine light came on. Code P1129 which is closed loop fueling not achived-bank 2. While I am happy I finally have a code, I am also pretty pissed and dont know what to do next. I know this is a fairly common problem, but I've done everything that has been posted on this forum and now im lost! And happy Memorial day!

 

AND I have changed the spark plugs.....my bad

 

Did you think about replacing the EGR valve? I think they are about $40 or so. Mind as well try that. It's about time for replacing it anyways...just my two cents.

 

Don't think he's got one. At least the '05 and prior 2500 Hemis don't.


You got a bad air/fuel mix, and the good thing is that's it's happening after closed loop, meaning the PCM is probably fine and it's sensor related. It's also a good reason why your fuel mileage is for sh*t. This could be caused by a few things. Most common is a leak somewhere in the intake system but can also be a bad or fouled MAP sensor, bad Throttle Position Sensor, bad PCV.

Since your RPM readings are way off I'm gonna assume it's not the gauge itself, so I'd replace the TPS first. A sure sign of a failed PCV, bad enough to cause a bad fuel mix is foaming of the oil up the tube, so check that too.

I know it's frustrating, but the code combined with your symptoms all point to a single issue, find it and fix it and you should be good...

 

My code list says
P1129 Downstream Heated O2 Sensors Swapped.
Maybe it is something you did lately that is causing the new P code to show.
What about fuel preasure, Intake leak, spray around the edges with WD 40 it washes off easy enough, it really does sound like a vaccum leak, or a miss fireing coil..

 

Thanks guys. @Hammer I have already changed the PCV and MAP sensor and the TPS is not a separate (replaceable) part from the throttle body. So Before I drop a couple hundred bucks on a throttle body, I would like to ask what your guys' best method for checking for a vacuum leak. The more detailed the better....as my name points out I am noob!! Also the last parts I changed were the 2 pre cat 02 sensors and then I got the code. I only changed them going off of some advice from a friend....but obviously did NOT fix ANYTHING!! Thanks guys!

 

You might be confusing the IAC (idle air control) valve with the TPS. I replaced mine for erratic idle and cleaned the IAC and mine idles like new and MPG went up to 14 in town from 11. Good luck

 

Just curious as to what mileage you are getting

 

@wolf22m-2006 2500's do not have and IAC or a TPS. Wish they did though! @weed-My MPG's are at 10.8 right now with VERY conservative driving! And by the way I did not find ANY VACUUM LEAK!! Man I wish I had...then this issue would have been figured out...maybe.

 

It is possible that you have a bad injector. It is perhaps not shutting off completely and dumping fuel into the engine when it shouldn't be.

Reference note: the downstream O2 sensor is the one after the converter. If it is out of range, it could be from an over rich condition.

Could also be a clogged cat.