ok guys iv been having issues with my truck not idling right. its fine when i first start it after a few mins. i can hear a vacuum leak was told to repalce the Idle Air Control valve.so i did that and can tell a difference in the way it idles but like before after it runs for a bit the vacuum leak starts again so i felt around and it's coming from the top side of the idle air control valve. my question is, is there so pose to be a gasket between the valve ant the throttle body? now there is a rubber gasket on the valve from the part store.

Thanks Guys ,

Andrew Brady

 

There isn't a gasket from what I can tell in the FSM (Factory Service Manual) for the IAC.......Have you done the plenum plate and gasket fix yet? It's a problematic issue for our engines, and can be a massive vacuum leak.

 

It's possible you've got a throttle body leak going on. I would pull the TB, clean it and the IAC, making sure you get in there and clean it out, then replace the TB gasket. Also make sure you've got the air cleaner ring that goes on top of the TB, that keeps the air cleaner from whistling.

 

+1 on both counts, especially with the air cleaner gasket. I had my cleaner off when I was doing a cap, rotor, wire, and plugs change, and it came off in pieces. I didn't think to buy this gasket when I bought the other stuff, but man did it whistle and run kinda crappy with it in that current condition. 99 cents (well, 1.06 with tax) and back to good

 

The 5.9 in my TJ does this same thing. After idling for a few minutes, it hisses like a vacuum leak and idles a little lower and a little rougher. I've sprayed cleaner all around the TB when it's doing this, no change. It was a new IAC, TPS, and Map when I built it in 08, maybe 5k on it since.

Might be a gasket, I'm guessing an IAC valve malfunction or leak in the idle circuit.

 

These trucks don't like most parts stores brand sensors or stepper motors. I think the IAC from Advance Auto is the only one that reliably works. But I can't remember the brand name off hand.

 

I've also heard the front 02 sensor causing the IAC to open early, leaning out the mixture and causing a rough idle. Might try that if you haven't replaced it.

 

Probably BWD IIRC Dodge Dude.....I also heard Standard Motor Products makes a good one as well, along with their sensor offerings being of great quality.

 

Yeah, BWD is the one. Though BWD has its own issues, just ask Redneck Ram about his Crankshaft sensor.

Standard is the one that Zman recommends as well as VDub.