Where is the IAC valve located?

[RollinSidewayz]

I have been having the following symptoms.. poor idle at times; difficulty holding idle upon cold startup (although I'm not really considering this due to my cam); running rough (almost like its missing); bucking while driving, particularly around 1900-2000K; change in exhaust tone at times... and I have a hunch that all of these are related.

Now from the searches I have done, it seems as though I should consider replacing the IAC but I don't know how/where its located. Does anybody have input for my situation?

*Also.. what plugs/gap and timing would you recommend for my combo?

 

[Jay5_o]

wtf is a IAC?

 

[87'GTstang]

It's the roughly 3" long cylindrical object mounted directly on the front of the TB. Just FYI, the IAC is highly related to the TPS and if the TPS is reading wrong it will tell the IAC to open too far or be closed too much. Try searching for the voltage test operation on it. Poor/dirty MAF could also give inaccurate readings.

Try adjusting timing up to 12 degrees, up 2 from stock (It widely depends on overall setup however).

 

[87'GTstang]

wtf is a IAC?

Try doing search before downing someone with a good and VERY common question.

FYI, Idle Air Controller
It's the valve that opens to let more or less air into the engine in accordance to and for compensation purposes to engine load.

 

[RacEoHolic330]

check those O2 sensors as well. I had some of the same problems as you and i found out that one of the electrical connectors was unhooked going to the driver side 02 sensor. Plugged it back in and the problems went away

 

[Jay5_o]

this is a tech section is it not ? and the thread was started whith a question related to IAC , hence thats why i asked so i could learn. No need to be an A$$ about it. And i was not downing anyone by asking what it was.

Oh.... and thanks for answering the question.

 

[jbrown]

Is the IAC located in the same place on the 4.6 sohc? My engine wont idle when its cold, and when its warm it idles at only 3-400 rpm. WTF!!

 

[jbrown]

Is the IAC located in the same place on the 4.6 sohc? My engine wont idle when its cold, and when its warm it idles at only 3-400 rpm. WTF!! My first guess is the iac but im not sure exactly where it is, is it the black box on the tb?

 

[89CopCoupe]

The IAC is in the gas tank .... you have to get a cutting torch and cut a large square outta the bottom of the tank with the torch. It takes less time if you have a full tank of gas as well ...... j/k

 

[Michael Yount]

jbrown - probably need to post your question in the modular forum.

Rollin- I'd pull the diagnostic codes and see what they tell you before you start replacing parts. And a good cleaning of both the IAC solenoid and the throttle body won't hurt anything. If they're original and stock, they are probably pretty dirty by now. Be very careful if you choose to try and clean the maf - they're a pretty delicate piece. Only hydrocarbon cleaners on all this stuff by the way.

 

[jbrown]

I did post in 4.6 forum, the one who replied wasnt positive of the location, I thought someone over here might know as well, just trying to get it fixed asap, Thanks though

Oh and I cut the hole in my gas tank (with the full tank of course), and all I can find is the fuel pump, I think Ill check in the trunk for the iac next...j/k

 

[Michael Yount]

Given that those solenoids simply bypass air around the throttle plate - I'm pretty sure it's located on the throttle body of the mod motors too. Shouldn't be too hard to find.

 

[HISSIN50]

a repair manual is a great investment. it will be useful for pics, descriptions and torque specs, on this project alone.

 

[87'GTstang]

Given that those solenoids simply bypass air around the throttle plate - I'm pretty sure it's located on the throttle body of the mod motors too. Shouldn't be too hard to find.

Ditto.........

 

[jrichker]

Dump the codes and see what the computer says is wrong…

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.dalidesign.com/hbook/eectest.html for more descriptive help
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at Walmart.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) http://www.veryuseful.com/mustang/tech/engine/ for pictures of the IAC (AKA IAB) & other parts

 

[FLA5.0]

Do yourself a favor before you go pullin and buyin parts, besides pullin codes as stated above. Check up under the upper intake plenum. Theres a small, (approx. 5/16 or 3/8), vacuum line under there that will crack and split and has apparently caused more than one of us, (me included), to go slightly mad searching out the source of a rough idle, (vacuum leak).