Re: high pitch noise from my 525 efi???
 

Throttle tension too tight, thus not being able to close the butterfly all the way. Take the throttle cable loose from its mount and see if it goes away.

Re: high pitch noise from my 525 efi???
 

While we're on the high idle topic, I have a similar (but different) problem. It's an EFI 454 mag...at startup it idles fine. As soon as you move the throttle it idles up to around 1500 and won't idle back down. If you shut it off and restart, it idles fine again until you move the throttle. Any ideas?

Re: high pitch noise from my 525 efi???
 

It turned out to be a old fashion vacum leak. The intake gasket was leaking. I went up to 1600 rpm and than 2100 at the end of the day. Real high pitch vacum whistle.

Re: high pitch noise from my 525 efi???
 

Glad you found your problem gsmith...
Any ideas on the above problem anyone??

Re: high pitch noise from my 525 efi???
 

Come on...somebody's got to have some ideas...

Re: high pitch noise from my 525 efi???
 

lowflyin,
It sounds like it could be your Idle Air Control (IAC) Motor or bad connection at the motor or ECM. Each time you shut the engine down the IAC resets. Then when you restart and throttle up it the IAC opens (like it should), but then can't back down due to open winding or a bad connection.

Dave

Re: high pitch noise from my 525 efi???
 

Dave, thanks for the response. Can you help me find/identify the ECM and IAC? This problem started after a rebuild so I suspected I might have re-connected something wrong, but it seems like all the connections can only be hooked up one way.

Re: high pitch noise from my 525 efi???
 

Can anyone shed a little light on this IAC, such as where it is, what it looks like and what it's function is? Under exactly what conditions does it open? If I need to replace can someone help me identify it?

Thank you oh great EFI gurus.

Re: high pitch noise from my 525 efi???
 

What engine do you have exactly?

Dave

Re: high pitch noise from my 525 efi???
 

It's all based on a 454 mag setup. The new motor is a 502 but I used all the running gear from the 454 mag and had the ECU reprogrammed and the injectors checked by Arizona Speed to make sure they flow enough. To answer your question though, I guess in this case I'd say a 454 mag MPI.