I have a 1996 Dodge Ram Van B2500. The issue is that, on occasion, when I come to a stop, such as a stoplight or stop-sign, the van will either rough idle and act likes its about to die but then catch itself or just flat out die. From this point I can put it in park and it will take off without a problem. It will also hesitate for 2 seconds from a stop, on occasion, like it's catching up with the acceleration I give it.

It only happens while at stop; on the long roads or the highway its smooth sailing.

No Codes at all.

So far I've replaced the Map Sensor, IAC Valve, Spark Plugs and Wires, Distributor, Serpentine Belt, Radiator Replaced, Fuel Vapor Canister, Purge Solenoid, Throttle Position Sensor, Camshaft Position Sensor.I also cleaned the IAC Valve port of throttle body, added factory recommended transmission fluid, and added fuel injector cleaner.

I'm kind of at a loss as I have taken it to two mechanics and each had no idea what it was.

Perhaps the O2 sensors need cleaning/replacing or the fuel injectors need to be cleaned more?

If you have any ideas, I would love to hear your recommendations.

 

I'm pretty sure the vans have the same 3.9 v6 as the trucks. I'd take a look into the intake and look for oil pooling. I had the same problems as you. Tried the same solutions. There's a sticky called the "end all be all plenum thread." That'll give you all the info you need. Good Luck.

 

Sorry should of added that its a 5.2L v8. I took a peak inside the throttle, didn't see any oil pooling. Is it possible for the plenum gasket to blow out and there not be oil pooling?

 

You might not have been able to see it if you only open the throttle body. Usually the oil pools in the back of the intake. In order to see this you would either have to keep the throttle wide open and get a telescopic mirror and flashlight or take the throttle body off and look in. The gaskets are very cheap and the throttle bodies don't take much to get off. I'm not sure how far your mechanical skills reach or what tools you have, but I'm sure if you find someone who does, it shouldn't take but a couple of hours. This problem with the oil in the intake happens with the v6 and both v8's. The intake sits above the lifter valley that has oil constantly going through it, so I'd guess it wouldn't be likely.

 

How many miles on your van? How old are the O2 sensors? Did you reset the PCM after changing those parts? Does it only do this after it warms up a bit? Or, will it do it immediately?

 

Is this an issue, the rough idle and a lower gasket on the 5.2/5.9L? This is what one cause for the rough idle is? I did a tuneup and all seemed well but the rough idle is back.

 

Blown plenum is basically a big vacuum leak, that also sucks oil into the intake. So, you get the strange behavior of a vacuum leak, plus, the burning oil fouls plugs, O2 sensors, and kills cats.

 

Okay good to know, thanks HeyYou

/threadjack