having problems with the IAC... details within.

[Mike86Stang]

Well for some reason I had my old IAC valve go nut's on me & then it crapped out. So I put on a new valve & now this IAC doen't seems to be getting a signal from the EEC.

Problems right now are typical of not having the IAC not working. Any reason why the EEC would not be controlling the IAC properly?

 

[crunchie12268]

how do you know that the EEC isn't detecting the IAC

 

[Mike86Stang]

Well I tried it on another car & it worked fine, plus it's new & my car will not start without holding the gas pedal down in the morning & now the TB is whistling (from previous experience I know this is b/c the IAC is not working.

 

[crunchie12268]

what about testing the connector with a multimeter? If the EEC isn't detecting it then it is way out of my league, but I think that is wierd how it doesn't detect it... I would think that the EEC is working but something else is wrong

 

[Mike86Stang]

 

[ss93cobra]

Something wrong with the harness would be my assumption. Have you tried having somebody test it with a breakout box?

 

[Mike86Stang]

I checked the continuity of the wiring already.... no dice even tried wiggling the harness with it probed.

 

[jrichker]

If you can lay hands on an old fashioned dwell meter, you can check the computer feed to the IAC. Back probe the IAC leads and connect the dwell meter across it. With the engine running you should see about midway on the scale with the meter set for 8 cylinders. No reading or the meter pegged in either direction means either bad wiring or a bad computer.

Edit: Use the 4 cylinder scale, not the 8 cylinder. I checked my notes and it said to use the 4 cylinder scale. Sorry about the oops.

If you had access to an oscilloscope, you can do the job more accurately. The waveform should be a square wave with about a 50% duty cycle. The computer increases the duty cycle to speed up the idle & decreases it to slow down the idle.

I would look very closely at the 10 pin connectors and the IAC wiring. Check the resistance between pin 21 on the computer and the white/lt blue wire on the IAC. It should read less than 1 ohm.

See http://www.autozone.com/images/cds/gif/large/0900823d80167158.gif for 86 model engine wiring diagrams

 

[Mike86Stang]

Thanks man, it always seems you have the answers I'm looking for

 

[HISSIN50]

yep, Joe is the man.

another thing as an aside, though 99.9% sure it is of no matter: some aftermarket IAC's require being mounted upside down - otherwise they reportedly dont work well at all.

i seriously doubt that is it - but you know how it goes. had i not mentioned that..........

good luck.

 

[Mike86Stang]

Upside down? The bastard wouldn't even fit under my hood!

Rollin down the street pimpin with my IAC sticking out of a hole in the hood NOT

 

[HISSIN50]

seriously, some do have to mount upside down to work right. i have not used one personally that mounted as such (they say how to mount it in the instructions).

LMAO - 'nope, that hole is not for the blower - it is for my IAC.' i would also have a hole for the top of the gerbil wheel (allows one to run a bigger gerbil wheel) to maximize the benefit of the forced induction. i would have an automatic food dispensor for the little guy too (for more reliable, consistant power).

 

[Mike86Stang]

lol, I've seen stranger things... it looks like a genuine ford part, but I'm going to take off the motor & see what happens.