I read a lot of posts about cleaning throttle body and passeges, I did just that, the truck idles and runs tons better, but a have a very high pitched noise around 3000 rpm, I replaced the throttle body gasket, checked all hose connections, and also cleaned K and N filter, I have the FIPK on it,, whille running I have sprayed throttle cleaner around hoses checking if engine will bog letting me know of a air leak but nothing, any suggestions?? maybe this sound has ben there all along?? or maybe i cleaned it to good, or maybe i should put some permatex high temp gasket sealent on the throttle body to elbow??

 

maybe a vacuum leak?

 

where do i start to check at for a vacumn leak?, its a high pitched sound, and i can play with the gas peddle when it does it, I make make it whistle, it wont do it when im park in idle at least i havnt heard it

 

Are you sure it's not a belt squeal?

Just check around all the lines you disconnected to take off you tb. One may have came loose by accident.

 

checked them all, there is one that comes off from the top drivers side and goes to brake booster, that one good, the one in back that goes to pvc, that one good, the one off the drivers side to the other top drivers side of engine, i took it off and I am cleaning it as i type, there are two elbows on it, im going to clean put back on and secure it better, i dont think that is it however, ill see

 

well, just hang in there. There are a lot of knowledgable people on here, that will know a lot more than I do. Hope you get it fixed, and keep us posted I'm curious as to what it is.

 

so am I, I dont know, maybe this is the way or sound it should have, It does run better, better response quicker, but for the past 4 days im trying to find this sound

 

well i found the source of the noise,, I probably cleaned it so well it gulping air,, I meen i had it in neutral in the garage played with the throttle and whammo it did it its coming from the K&N tubulance sucking air hard and i think good, sorta sounds like a jet engine, I dont think this is bad in fact its getting more air now than ever i think, oh well ill see if my mpg goes up in the next few weeks

 

Glad you found it...

Mine makes more of a growling sound when I get on it, that's why I was kinda confused...I have the MAC intake.

 

Replace the elbow hidden underneath the throttle body. That rubber elbow is a recall, along with the other end of that tube leading back to the pcv valve. All those elbows on my 97 f150 could not handle oil vapour (they all deteriorated) and collapsed under vacuum. That noise that came from my truck was soo loud, that I couldn't stand being under the hood! The elbow is hard to reach, but go buy a new one, or get the recall elbow for free from your local dealer. It is definitely a vacuum leak, soo small that it emitts a high pitched squeal.

To test if this is your problem, feel around for the elbow while it is squealing, to cover the vacuum leak. Squeal should immediately dissapper.

I originally took off the serpentine belt and started it up to see if it was a pulley related noise.

If you don't replace the elbows, your upper intake could fill with oil cake preventing the butterfly's opening smoothly on the 4.2 v6. Let me tell you how difficult that is to remove (had the intake gasket fail causing hydrolock- www.leakingfords.com )

 

Is it the rubber elbow in back of the throttle body?

 

also, make sure the 2 egr bolts are really snug. My 97 4.6 was whining/whistling. 10MM socket to tighten it up and whistling immediately stopped.

 

O3f150man ill do that i might of tried to get it off when i did the cleaning, good point they might be a little loose, i might just back them out and re tightned them anyway Ill keep you posted of what happenes, the whining is still there kinda drives me nuts

 

Hey do you still have the issue with the whining I have an OBX I put in the other day and it does the same thing did yours stop ?

 

6 year old thread. Likely the guy dont even own the truck anymore.