well i have a mind boggler that has myself and mechanic getting angry
i have a 97 ram 15 w 5.2 now truck will start run excellent till operating temp then it hits . two thing one you can be driving and then seems to lose all power you either have to clutch it and rev up or down shift and mat it to get moving . and the other is when you stop idle will drop right off and you can hear iac motor opening to compinsate and try to keep it going but if you turn truck off and restart will be fine for a while ... there are two codes in truck one is battery disconnected with in last fifty starts and that is fine other is 21 o2 sensor but from all my experience and o2 will not cause this issue there for im sure the issue whatever it is will be causing the 02 not to read right and set a code.... this is driving me up the wall has new wires cap rotor tsb has been done coil has been moisture tested for cracks or anything cat is not plugged runs too good and too long to have this as an issue and i can not anywhere find the egr so im sure mine is one built without ....

please help help its snowing and i have to move the snow ... thanks

 

Disconnect the pre-cat O2, and see if the symptoms go away. A failing O2 sensor could indeed do that.

Fixed the plenum yet? I don't think this is a clogging cat issue. Not yet, anyway.

 

Has fuel pressure been verified with a pressure tester when the problem occurs? And how do you know the cat is not clogged? When the cat heats up, or the truck is driven, the loose pieces can expand or move around and clog the outlet.

 

re cat: flow is consistant never changes , so im sure its not plugged but yes if i keep going like this it will indeed plug . and plenum no i have not done this as i just bought the truck and saw no reason to do such what is the issue with plenum ?> may i ask. and i will try to unplug pre cat 02 and see what happens but if i unplug it should that not cause and issue on its own ?

 

Leave it plugged into the electrical connector. Just unscrew it from the pipe. And read the Plenum thread on top of the forum.

 

sorry as for fuel pressure no not been tested at time being you just dont know when its going to happen . yesterday it idled for 40 minutes never a glitch today its happened three times in an hour. so its not predictable enough to know when it might happen .

 

So your mechanic has not tested fuel pressure? Maybe you should get a manual and try to diagnose the problem yourself. Just sayin' .

 

Well shucks, you just got some new experience, didn'tcha? The oxygen sensor can and very frequently when failed does cause precisely the symptoms you describe. Change it out with either a Denso or NTK part and your truck will get happy. Don't try the other brands because they're widely known to be iffy at best.

 

update : went to unplug sensor and i find there is no converter under there.... will that make a difference ? should i still un plug and test that method .

 

The absence of a converter won't affect the oxygen sensor. Unplugging it will force the PCM to stay in open loop mode -- which, if the truck runs better, indicates that the sensor is failed. But you don't want to run with it unplugged for long because it'll clobber your fuel economy and rob you of power the engine can make when it has a feedback loop to work with.

With no converter you don't need to remove the sensor from the pipe -- just unplug the electrical connector.