need help with IAC symptoms

[tbomb]

guys, i need some help pinpointing the infamous IAC issue. when my truck is idle i hear this "whistle", for lack of a better term. its not real high-pitched, like a teapot; its kinda like when someone tries to whistle, but they try to make a "deep whistle" sound, ya know what i mean? but it only does it at idle (by idle, i mean in PARK sitting still, or in DRIVE with my foot OFF the gas, just rolling.) i think it might be the IAC, but i wanna ask around before i go blow $100 on a new one. is there anyway to test it? (i doubt i can test for it, but i figured id ask.)

any help is appreciated, and, please, if possible, give as many details as possible.

thanks.

 

[Alec]

if the sound seems to be coming from the air filter, then it's probably the IAC.

 

[tbomb]

Originally posted by Alec
if the sound seems to be coming from the air filter, then it's probably the IAC.

alec, that brings up a good point; where exactly is the IAC located? i dont have my haynes manual here, so i cant check it out. (i never actually popped the hood to listen for it under there, but i will this week.)

also, anyone know of any good places to get an IAC valve cheap? i was just gonna check with napa if i needed one, but i dont know how much theyll charge me - theyre usually pretty reasonable.

thanks

 

[Alec]

on the OHV the IAC is located on the intake manifold close to the throttle body. It's a cylinder with 2 bolts and a harness.

 

[dogfriend]

re: price of IAC

They aren't as expensive as you think. I replaced mine 2 yrs ago. From the Ford Dealer, at that time it cost $60.24 plus tax. (F5TZ-9F715-B) The gasket (which looks like a figure 8 o-ring) cost an additional $6.96. (95TZ-9F670-AA)

 

[tbomb]

is it the same location and price for the SOHC?

 

[jasonb]

yes.. take off the little shroud thing that says 4.0K SOHC and you'll see it.
i don't know about price

 

[Macdaddy71]

maybe not IAC

i work as a tech at a ford dealer, and what you are talking about doesn't sound like it would be from the IAC, because i've worked on several sohc explorers and a few windstars that the whistling noise is actually from the plastic intake manifold itself, like a rough edge on the inside is causeing more turbulence and makeing the noise. Don't know why it would just suddenly appears on some of these cars, but they just do, its ford.

 

[BajaXplorer]

theres is a TSB on the SOHC Explorers concering the seperator plate in the auto trans that causes a whistling as well.
not a big deal and doesnt hurt anything although its annoying. The fix is a new seperator plate in the trans.

98-5, Publication Date: MARCH 16, 1998
1997-98 EXPLORER, MOUNTAINEER, RANGER

This TSB article is being republished in its entirety to include one chart to clarify the parts needed for repair.

ISSUE:
A "whistling" or "hissing" noise from the main control area may occur while idling in Drive and/or Reverse on some vehicles that have either a 4R44E or 5R55E transmission. This may be due to an improperly sized orifice hole in the main control separator plate.

ACTION:
Replace the separator plate with a revised separator plate. Refer to the following Service Procedure for details.


SERVICE PROCEDURE

1. Perform normal diagnosis by referring to the appropriate model/year Service or Workshop Manual.

2. Repair all Diagnostic Trouble Codes (DTCs) as listed.

3. Repair all transmission concerns as required.

4. Verify that the whistle/hiss noise still exists. If the condition still exists, install the revised Separator Plate (-7A00 onto the main control. Refer to the Service Manual for proper procedure. Refer to the following Application Chart for the correct separator plate.

NOTE:
IF A SYMPTOM OTHER THAN "WHISTLING/HISSING" REQUIRES REPLACING THE MAIN CONTROL, REFER TO THE MAIN CONTROL CHART WITH THE UPDATED PART NUMBERS FOR CORRECT APPLICATION.

 

[dogfriend]

Originally posted by BajaXplorer
theres is a TSB on the SOHC Explorers concering the seperator plate in the auto trans that causes a whistling as well.

Yes, mine has this so I believe that it applies to any Ex with 4R55E or 5R55E. It doesn't bother me. I noticed that it is not constant, it seems to depend upon temperature. I haven't heard it for awhile.

I don't think that it is the same issue as the IAC problem. I didn't replace my IAC due to humming or any noise problem; mine wasn't maintaining idle speed. I have read other threads on this board where a humming noise is caused by the IAC, so I believe that it is a problem with some explorers. It might be interesting to correlate the type of engine and model year(s) with the humming to see if it is a particular intake setup or if it occurs on all explorers.

 

[Robert]

tbomb - pop the little black cap off your IAC valve. If the noise goes away then the IAC is the source of your noise. If your idle is fine, you don't need to change your IAC valve unless the noise really bothers you. The black cap is about 1" in diameter mounted to the side of the IAC valve. It takes some effort to get it off. It has a sort of compression fit to it. Once you've taken it off, the next time you take it off is easier. I used some big needle nose pliers to take mine off. I put the pliers between the IAC valve and the black cap and pried outward. It went shooting across my garage once it popped off.

 

[tbomb]

hey, thanks for all the tips guys. ill check it out this weekend when i go back to my moms house and i have a garage and tools

 

[X24]

My idle is kinda rough and low (about 550). It has been stalling out on me lately. Sometime it stalls when I shift from reverse to drive or sometimes when I'm driving down the road and just take my foot off the gas. It always starts back up right after. I ordered an IAC valve from my dealer today and it will be in tomorrow. $77.26. Do these symptoms sound like a bad IAC valve?

 

[dogfriend]

Originally posted by 98FordX24
My idle is kinda rough and low (about 550). It has been stalling out on me lately. Sometime it stalls when I shift from reverse to drive or sometimes when I'm driving down the road and just take my foot off the gas. It always starts back up right after. I ordered an IAC valve from my dealer today and it will be in tomorrow. $77.26. Do these symptoms sound like a bad IAC valve?

Yes, but it is also possible it could be something else as well. Does it run okay if you open the throttle a little bit to compensate for the IAC not opening? If it does, then it is probably the IAC. If not, then a fuel problem or something else.

 

[X24]

I have no complaints when my foot is in the gas, except for it not shifting out of first faster.

 

[dogfriend]

uh...

What I meant was: when it is idling too slow (550 rpm) can you increase the speed of the engine to normal idle speed (~800) by giving it a little bit of throttle? If so, you are compensating for a non working IAC by letting more air in (what the IAC is supposed to do).

Another way to check is to unplug the connector on the IAC and see if there is a difference. If there is no difference, then it isn't working the way it is supposed to. If the engine dies as soon as you unplug, then it is doing something although it may not be working 100% correct.

 

[tbomb]

Originally posted by dogfriend
uh...

What I meant was: when it is idling too slow (550 rpm) can you increase the speed of the engine to normal idle speed (~800) by giving it a little bit of throttle? If so, you are compensating for a non working IAC by letting more air in (what the IAC is supposed to do).

Another way to check is to unplug the connector on the IAC and see if there is a difference. If there is no difference, then it isn't working the way it is supposed to. If the engine dies as soon as you unplug, then it is doing something although it may not be working 100% correct.

normal idle speed is 800 rpm? whered you hear that? my truck idles at ~600 rpm in park, and drops to ~500-550 in drive (at idle) <-- thats normal, well, for the sohc anyway.

 

[dogfriend]

Idle speed

I haven't actually measured the Explorer, cause I haven't needed to. Mine appears to idle at ~800. Usually the idle speed is on the sticker under hood, but not on my truck.

My 89 Ranger idle speed was 750 rpm and I had it on the digital tach lots of times to verify this.

Our 93 Toyota PU idle speed is 700 rpm adjustable.

I've never owned or worked on a vehicle with an idle speed lower than 700 but I suppose it is possible. Usually more difficult to get a smooth idle as the speed decreases.

I'm talking about idle speed in Park or N, not the speed of the engine under load in D.

 

[tbomb]

Re: Idle speed

Originally posted by dogfriend


I've never owned or worked on a vehicle with an idle speed lower than 700 but I suppose it is possible. Usually more difficult to get a smooth idle as the speed decreases.

im asssuming you have the ohv engine? heh, the sohc has anything but a smooth idle

 

[X24]

I have to agree with Tbomb. My idle has always been really low.