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Eric
Eric, Automotive Repair Shop Manager
Category: GMC
Satisfied Customers: 29941
Experience:  20+ yrs. experience as repair shop manager and technician.
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Not always but sometimes when I start off moving my 4.3

Customer Question

Not always but sometimes when I start off moving my 4.3 liter V6 in my Sonoma pickup sounds like a jet then releases what causes this?
Submitted: 1 year ago.
Category: GMC
Expert:  Gary replied 1 year ago.

is this noise from under the hood area ?

will it do this more so colder in the morning before it warms up ?

Customer: replied 1 year ago.
It's under the hood, it's like the sound of a choke not opening it happens wether hot or cold!!!
Expert:  Gary replied 1 year ago.

can you make it make this noise with the hood open revving it up ?

Customer: replied 1 year ago.
No only when starting off when you're in drive soon as you pull out it sounds like a jet it's under the hood it's coming from where the black hose is connected to the carburetor it seems like that valve in there/ the flap won't open up it has a plug/electrical wire connected to it. Is that the air/mass control or what. I noticed several 4.3 liter engines do it also
Expert:  Eric replied 1 year ago.
HI,
different expert here.
Ok, by the description, it sounds like this is the IAC idle air control valve at the throttle body. It has a pintle on the end of it that moves many times per millisecond that allows air past it. If sticking it will cause a jet like noise to come from the air intake tube going to the throttle body. While I commonly see this on Fords, I have seen this on many 4.3L GM engines as well.
You will need to replace the IAC valve to resolve this. Make sure to use an AC Delco brand. Many aftermarket brands will make this noise straight out of the box
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Expert:  Eric replied 1 year ago.
I noticed we have not yet resolved your concern you asked about. I would sure appreciate it if you would reply so I can offer my skills and knowledge and repair guide access to help as best I can.
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