Little over a year ago truck wouldn't idle...replaced IAC fixed the problem. Now the problems back. I cleaned and replaced the IAC no difference. Install a new IAC and couldn't it to idle below 1500rpm...returned for refund. Replace TPS and PVC valve, no change. Did notice when the pvc hose was disconnected from intake manifold it idled about 600 rpm. There was some oil buildup inside manifold on the pvc inlet side. Battery and connections are in good shape.

Any suggestions?

 

Check voltage on map sensor. Should be around 5 volts from the connector and from the sensor. If the sensor is drawing any less then it could be burnt out. If its fresh oil inside the manifold you could have an intake gasket leaking. These dodges are notorious for the plenum intake gasket leaking. Has it be burning a lot of oil lately?

 

maybe a quart between oil changes....don't think it's plenum gasket cause my issue would be consistent if it were blown.

Just for the heck of it I purchased another IAC from a different vendor. They pulled the same old p0505 code that AZ did.
Made sure the wiring was good between pcm and AIC and started it up.
Ran at 1500rpm for 30 seconds then jumped to 1800rpm and 15 seconds later settled at 2000rpm [I assume the 3 rpm steps is the pcm communicating]. Drove it for 15min. with no change.
Took it to a friend and cleared the code....same pattern 1500rpm-1800-2000rpm. Didn't throw the 0505 code till I restarted it the second time.

Put the old IAC back in and no idle.

pcm communication issue??

 

I give up.

Put old IAC back in, popped of idle adjustment cap and set idle at 750 rpm. Just have to live with the ck engine light on..... what harm can it do.

 

Have you tuned it up?

New plugs cap rotor all that?

Used a can/bottle or two of fuel system cleaner?

 

I went through this when i was trying to change my IAC.. got one locally from AZ and O'R's when i installed it it was all the way out and had to adjust it.. but the thing is it didnt work; it would sit in the RPM range your talking about unless i manually adjusted it and I had immediate check engine light. The thing flat out was not operating.

Finally I bought one from Rock Auto and solved the issue; No check engine light and smooth operation.

Sounds like the same issue I had; what your having now.

 

Thanks everyone for suggestions....trucks on its journey back home. I do lean toward the IAC issue more than a pcm problem. I cant remember where the 1st one was manufactured but the second was Mexico [1st likely was also]. I also can see the potential of damaging the pcm with the one i replaced a year and half ago, if indeed it didn't meet Dodges specs 100%.
It will be some time before i see the Dakota again but will keep in mind "who" manufactures the next one.
Did throw 1/2 can of Seafoam just to see if it might correct his gas gauge issue....but that's a different story.