I completed my 3.4 swap a few weeks ago, and due to a high idle issue I have been driving around with the IAC plugged off. Instead of getting a new IAC valve, I decided to buy a used throttle body off ebay (only $40 more than the IAC alone) since I wanted the cruise control pulley as well. (my JDM only came with throttle and transmission pulleys.)
Well, today I got the new TB installed, and the truck idles like a champ now. BUT, now there is a severely annoying humming sound coming from the throttle body. The frequency of it is absolutely unbearable in the cab.
I took a video trying to capture the sound, does anybody have any ideas? A couple hours of this while wheeling would drive a person mad.

 

Sorry I can't seem to figure out how to upload a video. yotatech says it's too big and filesharing says invalid address. I'm stumped.

 

Ok here's a youtube link to the video. Any help appreciated.

 

You're missing atleast one vacuum line cap, right on top of the TB. One of the ERPG lettered lines. Probably it's other end is open also..

 

I must have knocked it off when I installed the TB, I didn't even notice. I'll pull one off the old one. The other one that is open under the plenum is just a pipe that goes nowhere, its open on both ends, just in case anyone else sees that.
What is ERPG by the way?

 

Ok I plugged it off again, but nothing changed. What do you mean “the other end”. I don’t see anything else to plug off.

 

Anybody else run into this? I used a new gasket when I swapped the TB...
One thing to note, the noise doesn't appear until the engine hits operating temp and the idle settles all the way down.

 

Try capping off those ICS water ports you're not using, you could have a bad seal in there (which is maybe why you bypassed the water passage here?)

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I didn't bypass anything... I'm not sure what you saw there.
Everything is hooked up where it should be.

 

No ideas?

 

What EVAP system are you running? I am going with the charcoal canister (thought I could see it in your video) but I have heard rumors that it makes an obnoxious noise on 3.4 swaps.

 

Interesting...
I am using the original 3VZ evap canister. However, the noise seems to be dead center of the throttle body. I'm starting to suspect the IAC since the noise doesn't exist until the engine hits operating temp.