I reset the check engine light.... again. The pvc valve was every dirty. I cleaned it just to make sure that was working okay. I traced and checked all the vacuum lines that I could. One went in behind where the windshield wiper area is, so I don't know about that one. I did have to do some more running today. No check engine light, and the engine was running smooth, with no vibration at all. I also didn't run the ac today. I'm going to run the fuel down and run some more cleaner through it. Maybe a double dose of cleaner will clean up a border line Cat.

 

I got this off of all experts. what ya think?
One code is for the left converter pathway and one is for the right pathway, so both sides are detecting the problem. My thought is that the rough idle may be causing the issue. In the absence of any other codes my suggestion would be to check whether the exhaust gas recirculation valve may be sticking ajar when you slow down to a stop.
Look for the valve by following a narrow diameter exhaust pipe that branches off the rear side exhaust manifold. The valve has a round vacuum-operated top piece and between that and the body of the valve there is a flange which may hide from view the valve stem. So find that stem and notice that it has a slot into which you can insert the tip of a screwdriver. Move the stem back and forth and notice if it is closing tightly to a dead stop via the internal spring-action. If it is sticky then spray some solvent like WD-40 on the stem where is enters the body of the valve, and then work the stem a bit more to free up the action. That may solve both problems.

 

A 3.9 does not have an egr. It uses a manifold absolute pressure sensor. You can test the map sensor by probing the center wire on its wire connector with a voltmeter. With the ignition on but engine not running you should have 4.5 to 5 volts on the center wire. Start the truck and once the engine gets hot the map voltage should drop but not go any lower than 1.5 volts. It should also increase some as you goose the throttle on a hot idle. Any less than 1.5 volts means the map is bad. A bad map sensor can also cause the idle and stalling problems you have. It can also make your engine run too rich which could have caused the problem you have with the cat.

Jimmy

 

Here we go sir.
Cold engine no start 4.7 volts
Cold engine Running 1.5 volts (just started)
Warm engine running 1.2 volts
Revving up the engine the volts went down.

 

I ordered it. I'll pick it up a little later today and install it, then we'll see. I really don't want to put another exhaust on it.

 

I hope it solves the problem for you. Here is a very long but informative thread about the MAP sensor and how a new one can help your truck:

https://dodgeforum.com/forum/2nd-gen...er-solved.html

I am in there a few times myself. That thread was where I learned what MAP sensors are and what they do. Some of the guys in the thread are not on here any more, I guess they moved on but it is still a very good thread anyway. One other thing to remember is you can have an incorrect MAP signal and still not have a code for it. Problems with the engine management sensors and PCI bus on Dakota's can be difficult to diagnose and fix.

Good luck with it and let us know what happens.

Jimmy

 

The gremlins are back. P0420 P0423. Don't they ever go away? I really need to find out what is going on. I guess to the shop It going to have to go. Man, I hate that.

 

A good shop can test your exhaust stream and fuel trim data and tell you if the cat is bad. It may be best to take the truck to a custom exhaust or shop that only works on emissions and exhaust. Did the new map sensor help with the rough idle?

Jimmy

 

No it still does it on occasion.

 

I have come to the conclusion the cats are gone. I Will be changing the exhaust. I want to put a thrush on it and the Exhaust looks to be about ready to go anyway. At the same time I'm under it I need to replace the rear main engine seal a and the clutch bearing is making a little noise. I would not have bought it but I wanted a red truck.