High Pitched Whistling?

[hobber]

I am getting a high pitched whistling that sounds as if it coming from the back right of the engine. Maybe under the plenum. Sounds like it may be a vacum leak. I have tried to pinpoint it by spraying carb cleaner, but not change in idle.

One of the earlier posts, indicated the same sound. Those who weighed in thought it may have been the fuel pressure regulator vacuum connection. Where is this connection? I would like to check it. Thanks.

Will appreciate any help in identifying this sound.

[PalmerWMD]

A tiny exhaust leak can sometimes cause a whistle like that.

Fred...

[DAEDALUS]

The regulator is behind the plenum, between the IAC and the BPT. I had to unbolt the BPT to reach it. Just a bit too tight a squeeze otherwise for my hand. It's to the left of the IAC (if you're sitting in the driver's seat). Sqeeze the vacuum line and see if the whistling changes.

[hobber]

I checked the regulator hoses, and if I remove the top hose, the whistling goes away. I assumed that the hose was bad, so I replaced it. The whistling seems to have gone away, but when the engine is cold, I get a rough idle and the engine is hunting for the proper idle speed. Once the completly warm the egine smooths out.

Is it likely that I have a bad fuel pressure regulator? I read a thread from a week or two ago, and the Moderator said they almost never go bad. Just replaced the injectors, replaced fuel filter, put on new throddle body, checked MAF connection, and had a power balance test completed.

What am I missing?

[DAEDALUS]

You may still have a leak somewhere. Hunting is a symptom of this, though a rough idle could be several things. If you've tried the carb cleaner spray I'm not sure what else to recommend, other than to verify the regulator hose is hooked up properly, do a visual inspection of all vacuum hoses, and check around the plenum seals for leaks.

[hobber]

As I was checking the connection of the fuel pressure reg. hoses, one hose was on rather tightly, and as I pulled on it, the cap of the regulator moved. The whistling has gone away, but I am concerned that the movement in the top of the regulator means that it is damaged.

Does anyone have any experience with this? I have a old fuel pressure reg. from another Q. I check the it's top and it moves as well. Because the old reg. is a junk part, I am not certain it is in working condition.

[DAEDALUS]

Have you checked the fuel pressure? Nice tool to have, and you can get one for less than $30. That should tell you if the regulator is doing its job, assuming the pump/controller are in good order.

[DAEDALUS]

I just noticed that you used carb cleaner to check for leaks by looking for a change in idle. I usually find the mist more helpful visually by allowing me to see if the little droplets are getting sucked in to a particular area. With a strong light at the right angle, this can be very revealing.

[hobber]

Thanks Daedalus. I will try that.