Ford Mustang Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Hey guys new to this forum I had originally been posting over at Mustang Forums but that one seems like its almost dead. Therefore I am going to try it over here and hopefully yall can help me out. I have a 1994 Mustang that was originally a V6 auto and I have converted it to a V8 manual trans with a GT40P motor from an explorer with the fox body throttle swap using a BBK 70MM throttle body and corresponding MAF sensor. The car doesn’t have emissions on it outside of cats. https://mustangforums.com/forum/attachments/5-0l-1979-1995-mustang/77649d1598490390-1994-mustang-gt-whistling-at-idle-img_3469.movI have done a lot of research on this and come up with some different things including filling down the inlets to the IAC and checking to make sure there isn’t a vacuum leak. I don’t have a vacuum leak that I can find and the car doesn’t run like anything I have ever owned that did have a vacuum leak. I also don’t have any check engine lights going on. I am attaching a video clip and y’all can hear the whistle that goes away as soon as I increase the throttle. If y’all have any ideas I would greatly appreciate it.
 

·
Registered
Joined
·
23,556 Posts
Put the stock throttle body and cold air intake back on

it is tuned by ford

or turn the stereo up

the source of the whistle is the cheesy throttle body
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
So are you saying that the BBK throttle body isn’t any good? If so why is it one of the swaps that everyone suggests? I also do not have a stock throttle body or cold air intake as I previously stated the engine was a swap and it came from an Explorer so there was no stock throttle body.
 

·
Registered
Joined
·
23,556 Posts
first rule, dont listen to everyone

then try an acuufab

i have a 90mm and can't hear a whistle

or find the stock stuff at a wrecker, so there always a solution
 

·
Registered
Joined
·
3,939 Posts
It’s definitely the throttle body whistling.

It could possibly be one of the TB or EGR spacer gaskets leaking, try to tighten down the bolts a little or use a smoke test.

The cheaper throttle bodies are known to leak around the butterfly valve shaft.

Been there, done that.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #6
Thanks Hybred I guess i will try machining them like other people have suggested and go from there.
 

·
Registered
Joined
·
3,939 Posts
Machining what?

Just replace the throttle body.

Or you can go screw something else up and complain about surging & stalling afterwards.
 

·
Corral Charter Member
Joined
·
11,315 Posts
Just a side note to the above excellent tech advice:
I also recall years ago that if a Fox IAC was used on a 94/95 instead of the original SN95 IAC, there would be a whistle effect.
 

·
Registered
Joined
·
3,939 Posts
Mine is a Blower, lol 😆
 

·
Registered
Joined
·
23,556 Posts
what part of “IAC” did you miss?
 
  • Like
Reactions: HYBRED

·
Registered
Joined
·
9 Posts
Discussion Starter #13
Indy2000. I missread his message. Also I don‘t need you on here being a dick you can go ahead and leave since you have nothing actually helpful to say.

CobraJet when you say the Fox IAC used instead of a 94/95 IAC does that pertain to if I am using the SN95 throttle body and intake? Because I have tried the 94/95 IAC and the car wont run at all with the Explorer GT40P intake and a Fox throttle body.
 

·
Registered
Joined
·
23,556 Posts
you have been told what to do, its not the answer you like
 
  • Like
Reactions: HYBRED

·
Registered
Joined
·
9 Posts
Discussion Starter #15
I haven’t even replied because I knew what the answer was to my initial question from the answers that have received earlier. I was trying to learn a little bit about what CobraJet was talking about in case it did happen to pertain to my situation before I purchase a new throttle body. So stop being a douche and take your comments elsewhere please.
 

·
Registered
Joined
·
3,939 Posts
Do you have a FOX IAC & a SN95 throttle body?

No.
No, you don’t.

Why is that hard for you to figure out?

Your BBK throttle body is causing the whistle.
 

·
Corral Charter Member
Joined
·
11,315 Posts
It could be the TB as suggested, but there have been past issues reported that the whistle can also be traced to a bad or failing IAC, OR a combined IAC/TB issue.

The most common cause of the whistle:
The TB is not port matched to the intake it’s being used on, period. For instance, running a 70mm, 80mm or 90mm TB up against an upper intake intake (or for most foxes, EGR spacer+intake) that is only 65mm....

My prior comment regarding the IAC:
In the past, some people thought they could interchange the Fox IAC with the SN95 IAC, because why not, they’re both 5.0’s right? Wrong. The IAC‘s can’t be swapped between the two, unless the user wants idle issues and the whistle. This is because the internal design volume of the 2 IAC’s is different as well as the internal spring pressure and each was designed for a specific application where it’s also port matched to the TB.

Now there have also been issues where after installing an aftermarket TB a whistle suddenly surfaced. This has been discussed in many threads across multiple forums. As Hybred and Indy2000 have initially suggested, yes it could be just the aftermarket TB (tolerances or QC issues). Not the fact that aftermarket TB‘s are just “cheap”, but because some manufacturers don’t properly cut the throttle blade correctly (not be chamfered down correctly). Due to the possible anomalies with the aftermarket TB’s, the airflow between, through and over the TB blade is what causes air turbulence and interference with the IAC, thus resulting in the whistle. Some of the cheaper knockoff TB‘s don’t even have a small hole drilled through the throttle blade which also causes turbulence issues.

Some folks are good with a dremel and or a file to chamfer down the TB and eliminate the whistle, but if too much metal is taken off or the DIYer distorts the TB blade, or drills too large of a hole in the TB blade, then he/she ends up with idle issues and even drivability issues - which at that point they now have a $200+ paperweight.

Here’s more reading for you...

THIS old thread has almost a mirror example of your setup and the whistle, so it may be good reading:

Another old thread, with a supposed fix:

Old Corral thread:

In case you have not stumbled upon this on the net, it is directly from BBK’s site:
Q. Why does my throttle body whistle? What can I do?
(part numbers affected include: 1501, 1503, 1514, 1517, 3501, 3502, 3503, 1534, 1536, 1537, 1539, 1540, 1542, 1543, 1544, 1522, 1523, 1524, 1715, 1700, 1701, 1703,1580, 1705, 1711, 17110, 1755, 1708, 1709, 1710, 1721, 1756, 1757, 1546, 1547, 1752, 1753, 1751, 1754, 1548, 1552, 1652, 1723, 1716)


A. Turbulence in the airflow stream can create a whistle. This can be created by sharp edges in the air intake system, most notably when a larger throttle body is used on a stock intake that has not been 'Port Matched.' The air along the outer edges of the air intake system and throttle body hits the "wall" of the smaller intake manifold, creating turbulence that can cause a noticeable whistle. Other trouble areas can be the small vacuum ports and the IAC (Idle Air Control) valve port which may empty into the main bore of the throttle body. If these edges are square enough at the entry point of the bore, it can create turbulence, and the air will whistle passed it (similar to blowing over the top of an empty cola bottle just right to get it to whistle).

If you feel you are adept enough with simple hand tools, you may want to try and hone the ports yourself with fine grit sandpaper. Some customers are adept enough with a small drill or Dremel-type tool to lightly sand the edges down. Be aware though, that any irreparable damages done to the product on the customers behalf cannot be warranted by BBK. Be aware though, that further honing the throttle body may not cure any whistling issues if the problem actually lies elsewhere in the system, and if the added airflow of a larger-bore throttle body is only making the problem perceptible.

—-
Aside from the above, calling long time knowledgable Corralers a “dick” isn’t any way to make friends (or get future help). Indy2000 gave excellent advice as did Hybred - both respectable members of this site. Their answers may sometimes be brief, but their hearts are vested in this site as well as their time helping any member. Their way of responding is to get users to think more about the diagnostics and proper testing aspects, rather than just throwing parts at a problem and still not coming to a resolution. Sometimes their response is short to heed their advice, because there just isn’t any further explanation needed - which may not be a suitable type of response for all, but if you know their response styles, you’ll “get it”.

Good luck, hopefully something above helps.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #19
I appreciate your response Cobra Jet and the information that was linked as well as the considerate manner in which you responded. It was quite helpful and that's what I was looking for was an opportunity to work through the problem as opposed to just throwing expensive parts at the car and hoping it would fix the issue.
 

·
Registered
Joined
·
364 Posts
Well said CJ. Its too bad that some others would not take the time and show some respect and be more helpful especially with new members. It seems that there are a few that like to bait new members and then pile on.

Most of those from 10,15 years ago that contributed so much to this forum are long gone. And a lot of possible new members left the scene real quick because of the condescending attitude of a few that should have been kicked out long ago. This forum has dwindled and been on a lifeline for years. But it has been kept intact and needs some new blood to build it back up. With your help, maybe that will happen.

No one knows a new members ability or there budget or whether there are truly ready to be addicted and dedicated to this hobby of hot rodding. Old time members like yourself are still needed around here.

Very well done. And redneck, welcome to the site and enjoy yourself. Ignore the dicks that are looking to "bait" you.
 
1 - 20 of 21 Posts
Top