My 4.6L engine in my wifes car with 110,000 miles is making a noise that reverbs through the air cleaner. It sounds like a continous low whaaaaawww coming from the throat of the throttle body. If I hit the gas and rev the engine it goes away. It also makes the noise while driving at a constant speed unless I rev the engine. I cleaned the throttle body butterfly valve with carb cleaner and removed the oil buildup from the PVC. I have changed the air cleaner also.

I saw a ford technical bulliten on IAC bypass valve moan Anybody heard of it or had this problem?

thanks

 

I've only ever heard that noise on a '93 Grand Marquis 4.6L at a used car lot. It didn't seem to affect the way the engine ran, but I didn't feel comfortable buying it.

 

I have had the same problem on my 4.6 and did pretty much the same things, did you find anything with the bypass valve?

 

I have a 95 explorer that was just smoged and it almost failed due to the IAC being clogged by carbon deposits. I was told it needs a full intake cleaning to remove carbon buildup on intake manifold, throttle body, and IAC. This was the problem for my explorer, sounds simular to yours.

 

Hi Folly5678;
The IAC valve moaning is caused by the actuator overworking, because of the dual chamber valve not sliding properly/hanging up, or a weakened actuator trying to do it's job. (Solonoid over workworking leads to the weakened state of the actuator! (A vicious cycle)
_________________________________
The Brain Is Always On The Move
______________________________________________
My Beastie:
90 Ranger 2.3L EFI 2wd Mazda < with many new parts!

 

It can also be caused by a clogged filter on the IAC. The filter is under the small black plastic cylinder on the IAC housing. Cleaning the filter might help.

Another cause is from air traveling through the (IAC) filter, then through the IAC housing into the intake. This happens when the actuator seal gets worn.

The moaning is annoying but not serious.

 

Thanks, I took it off and cleaned it. Used carb cleaner and air? It seemed to alost cure it, but I still get a little. Guess next step is to just break down and get a new one.

 

Here is some info that might apply to your noise problem, recently had a 1994 crown vic. with a 4.6 at the shop and the customer complaint was the same as you fellows are describing. On the crown vic. there was a ford bulliten for a change up on the feed pipe to the iac motor, (the new hose /pipe has a small muffler built into it). Ordered one and yes it was the cure. (sorry I dont have part #s or bulliten # on hand) but i'm sure your local ford dealer can help you, If not let me know and I will see if I can find somthing on alldata or mitchel. regards, Domenico.......