Whistling sound in 1995 4.0L

[scawtiedog]

Help!! Whistling sound in 1995 4.0L

I tried searching for my problem, but couldn't seem to find any threads with similar problems (maybe there are and I just haven't found them).

Here's my problem. When I have the pedal at a certain point, I can hear a high-pitched whistling coming from somewhere in the engine. If I push it farther in or let up on it, it stops. It doesn't matter how fast I'm going, it's just a certain point on the pedal. From the sound and feel it seems like it may have something to do with the fuel injection or something. Any ideas????

 

[RiverRat]

How about a IAC (intake air control valve), vacuum leak, throttle body? Just some guesses.

 

[sodjer6]

I've had the same problem for the last year and a half. It only whistles at 2100rpm, and I know it's not the IAC. I think it has something to do with the intake, mine is all stock, except for the K&N filter. When I dropped that in the whistle got a little louder...

 

[Alec]

I'd check your intake manifold bolts an make sure the manifolds have a good seal.

 

[scawtiedog]

Thanks for the quick replies. Since I'm not much of a mechanic (I'm trying to learn), are there easy ways to check all these things? I have a manual to help, but I'm just curious if there's some easy checks I can do before I start going through that.

 

['96explorereddiebauer]

It might be your IAC. Here's a thread by Dogfriend about it along with a video. Match the sound with your truck's sound and let us know if that is it.

http://www.explorerforum.com/forums/showthread.php?threadid=85293&highlight=iac

 

[scawtiedog]

I don't think that's it, mine's not that loud. I keep asking my wife if she hears it but it's so quiet she can't. I haven't had time to get under the hood and see for sure, but I'll try and check it out this evening or sometime tomorrow just to be sure. Any other ideas if it's not the IAC?

 

[scawtiedog]

bump

 

[scawtiedog]

Okay, so I was finally able to check out the noise in my X this weekend. However, when I had someone rev the engine up to the point I've been hearing the squeaking/whistling, it didn't make the noise. We tried doing it in both Park and Neutral (I've got an auto) to no avail. Does this make sense to anyone??? I was hoping I'd be able to pinpoint it like was done in the thread '96explorereddiebauer pointed me to, but we couldn't even hear it. And it's not like it went away, because when I drove home, it was still making the noise.

BTW: It happens right around 2100-2300 RPM if that helps.

 

[Rhett]

I can tell you all about that, and what I think it is.
My truck has been doing that ever since I...
...
replaced the upper intake manifold gasket.

So. I would suspect that first. It's kind of a high-pitched tweety sound, at partial throttle, seems more prevalent when the truck is cold. It's NOT belt chirp. I'm convinced it's either a vac leak around the upper intake manifold, or it's a leak around the EGR fitting. That's the only other possibility, as the EGR is the only part that came off the manifold when I removed it, and the EGR gasket was cracked; not having another, I put the old one back.IAC wasn't touched, other than being unplugged. I need to take time out and re-torque the upper intake manifold bolts (they're easy to get to, unlike the lowers) and see what happens. FYI I used an OEM Ford gasket when I did that.

I'm not ruling out IAC, but if I had to prioritize, I'd say:

1) upper intake manifold air leak
2) EGR leak around the EGR gasket
3) IAC

Let me know what you think, and if you solve it..

 

[scawtiedog]

Okay, I think I understood some of what you were saying. So I should check the upper intake manifold and the EGR, even though I haven't done anything with them (you said it happened when you replaced yours)? On those, what/where exactly am I looking for/at?

 

[scawtiedog]

bump

 

[Rhett]

I would just make sure the upper intake manifold bolts are torqued to spec. They can loosen over time due to vibration, even if you never mess with them. Same with the two bolts that hold the EGR fitting on, make sure they're snug.

I started noticing the bird tweet sound after I replaced the upper intake manifold gasket on my truck. In order to replace that gasket, you have to remove the EGR fitting which is attached to the upper intake manifold.
So when I removed the EGR, it cracked the old worn out piece of cardboard that fit around the EGR (the EGR gasket). I didn't have a new EGR gasket so I re-used the old cracked one. Maybe this explains the bird tweet sound.

I also leave open the possibility of having a BAD BELT TENSIONER, but with that I would think it would tweet all the time, not just when cold. I'm going to re-torque the bolts this weekend and if that doesn't solve it then I'll break down and put on a new tensioner.

 

[scawtiedog]

Thanks Rhett, I'll check it out this weekend and let you know what I find.