Hello, I've been lurking on here for a while. I recently purchased a 2000 Dodge ram 3500 extended van. It only has 60k original miles on it. I changed spark plugs wires and gave it an oil change after I purchased it last month. The engine light has been on since I bought it. I reset it and it came right back on. I tried cleaning the IAC as per instructions on this site. It did no good. I changed the PCV valve and also bought and installed a new IAC at NAPA after the cleaning didn't work. It was fine for about a week I guess. Not anymore. My problem is, after the truck warms up, it idles very high, only after it has been running (driving) for 15 minutes or so. If it's sitting still in park, it idles fine for hours. Should I replace the 02 sensor also? Could it be the computer? And most important, can I just unhook the electrical connector? Would that keep the "pintle" on the IAC from opening and closing? When it starts idling too high I can feel/hear it acting erratically. It idles at 35mph (I don't have an RPM guage) and I can drive down the road with my foot off the accelerator and feel/hear the IAC "kicking in and out". So what would happen if I disconnect the wire connector? Would it harm the computer or anything else? Would the IAC stop opening and closing and just stay in one position? Any ideas?

 

It sounds like you could have the infamous plenum gasket leak. Even though your's is a 2000, the engine could've been made in 1999.
http://dodgeram.info/tsb/2000/09-05-00.htm

 

I'll check this out when it quits raining. In the meantime is there any way to tell when the engine was actually built? and does it hurt to unplug the IAC?

 

It most likely won't hurt but it will throw another code. Also when you start it in the morning it will not idle right if it even starts. The PCM controls the IAC and allow more air/fuel on a cold start then needed for a hot start, with out the IAC connected you may have a problem getting it started.

Other factors the PCM adjust the IAC for is AC compressor being on, engine temp and load.

 

Also when the steering wheel is turned. The added load from the pump would drop the RPMs otherwise.

 

Not by you or I. There are marking on the block that the factory can make sense of and know right down to the day and shift that made the major pieces like the block, heads, and manifolds. That's that symbol cast in that looks like a little clock with numbers and a pointer in the center.

 

Thanks for the replies. I'm gonna check the first part of this- (http://dodgeram.info/tsb/2000/09-05-00.htm ) out today since I don't have a job scheduled and the rain has quit. I got this van for a bargain at $1500.00 with 60k on it so I shouldn't complain about sinking a little money into it if I have to. I forgot to mention that it did sit for about 9 months before I bought it. It was a church van and they changed to using mini busses instead, because the elderly members they picked up had trouble climbing in and out of the seats. It's my church so i'm familiar with its history.

Mobile Auto Repair- you mentioned that the PCM also adjusts the IAC for the AC compressor being turned on. I forgot to mention that after I installed the new IAC, a few days later I refilled the a/c refrigerant and started using the a/c. The next day or shortly thereafter is when the IAC started acting up again. Any possible relation?

 

I doubt it for the two are on different circuits from the PCM.

Let us know what you find from the TSB 09-05-00.

 

Okay, bear with me. I went out and bought a vacuum gauge. Warmed up the truck and shut it down. Hooked up the gauge to the end of the breather hose, then disconnected the pcv valve hose and sealed off both of the open ends. I started the truck and the gauge started moving to the right hand side of the gauge where it says fuel pump pressure. It hit 3 psi in about 20 seconds and I shut the engine down. Is this the right type of gauge? Shouldn't the needle have moved to the left instead of the right? Is my only alternative to replace the plenum gasket now? I mean this is a major job isn't it? Is this normal for a truck that only has 60k on it? Forgive my stupid questions, i'm not too sharp when it comes to working on vehicles other than the basic tune up type things.

 

One more observation (or stupid question)- If I disconnect the pcv valve hose and plug both ends with my fingers while the truck is already running the engine dies immediately. Is this normal?