LS Throttle Body Whistle
I have a very loud whistle coming from the throttle body at partial throttle under load. I've been told it's coming from the IAC port. Anyone have a fix for this?
Basic parameters:
5.3l LY5 block from a 2007 Silverado. DOD deleted, LS9 cam and upgraded springs installed. Trail Blazer SS intake with 70050 standalone LS harness and ECU and FiTech loaded 92mm throttle body. Running 2 O2 sensors and Advanced Adapter headers with a true dual exhaust. All bolted to an SM465 transmission and Dana 18 t-case. Stuffed into a 1965 Jeep CJ5.
In general the motor starts, idles, and runs really well both hot and cold. I'm using the pre-canned tune with Cam set at 2 and let it learn. About 1300 miles on it so far. I did check the IAC setting, adjusted the throttle stop screw, and IAC is currently at about 6 at idle.
Any help would be appreciated.
Thanks,
Mike
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Many people cured this by porting/radiusing the IAC valve port in the throttle body.
Some also reduced the whistling by fooling with the IAC steps.
Quote from Paul Bell on August 6, 2020, 12:02 pmMany people cured this by porting/radiusing the IAC valve port in the throttle body.
Some also reduced the whistling by fooling with the IAC steps.
I am interested on this. Where can I get more information or picture on doing this porting?
I contacted FITech about this issue yesterday as it's present in my setup as well. They had no suggestions for how to reduce or eliminate the annoying whistle from the IAC in the throttle body. That surprises me somewhat as a search for throttle body or IAC noise/whistle returns a number of hits. So others are experiencing it too and have either found a way around it or are just sucking it up and living with it.
I removed the IAC from the throttle body with the two small Allen screws and peered into the opening. It looked like the contact area for the IAC pintle had a very small chamfer. I'm unsure whether the noise is coming from the seat area or somewhere else in the throttle body. I'm hoping that by resurrecting this thread, someone will post more details about potential fixes. Thanks.