Hello,


New to the forum but what I can tell this forum is full of very knowledgeable people.


I have a 2004 Dakota with the 4.7. Just recently it started idling rough but wouldn't cut out on me. Until last week I pulled into a parking spot and the truck shut off. No sputter, just off. Fired right back up with no hesitation but idled rough. The truck was idling low around 350-400. Two days ago the truck would fire up but immediately die as the rpms came down. Again no sputter just off. It fires right back up but keeps shutting off. When I give it gas and slowly let the rpms come down it will stay idling at 350-400 rpms. As its idling I will hear a popping sound coming through my K&N. I had my mechanic put it on his computer and sure enough it was misfiring on all cylinders. It wasn't a constant misfire but there was more occurrences on cylinder #4. He tried to increase the rpms using the computer but the truck would not do anything. There is no codes being thrown. I replaced the crank sensor and that didn't work. I also took the TB off and cleaned it good and reset the PCM. That worked for 2 startups and then went back to the way it was before. Not sure what to look at next. Thank you in advance.

 

Fuel pressure ok. ?

 

Fuel pressure is 52 psi.

 

Did you replace the map sensor?

 

I have not. I would think a bad map sensor would throw a code.

 

One thing ive learned working on trucks is wiring can do some mysterious things.. lol

 

Do these trucks have EGR valves?

 

There is no EGR in '04.

Swap the coil pack on #4 with one of the other cylinder to see if the misfire follows. How are the plugs themselves?

While not likely considering it ran better after cleaning the throttle body, thrown rockers and dropped valve seats do happen on the 4.7. You might pull the valve cover or run a compression check.

MAP sensors and the TPS sensor do not always throw codes.

 

Misfire did not follow. When I pull the vacuum hose that goes from the throttle body to the purge solenoid it idles fine as soon as I put the hose back on the truck dies. Could the solenoid be causing my problems.

 

Pull the hose and do what with it? Leave it disconnected or plugged?