hey guys first time posting on this board and im just wondering if there is a way to know if your IAC is bad, currently my 87 bird with 350 will start but will not idle which leads to to believe the IAC is my problem, i just removed the IAC cleaned the living crap out of it, lots of crap came off it, re-installed it and still would not idle. i dont have any engine codes, i found that if a keep my code reader on the car it would run roughtly but never the lesss it would run. when it is running the maf voltage not reads about 350 to 250mv. it does sound like a have a supercharger but the sound comes from my airfilter and the area when the IAC is on the front of the throttle body. this problem baffels me, im going to my local parts store tommorow to get another 1 but be4 i do i would like you guys opinions. one thing i did notice about the IAC when i had it pulled out is that there is no movement in the spring when i press down on it even after i cleaned it, i donno is this is normal or not jsut something i observed. i would appriciate all the help i can get thanks

 

hmm tricky... a bad IAC would be horrible idling... if ur maf is fine make sure u dont have any leaks after the MAF, any vacume leaks? or stuff like that.... the IACs have to be set at a certain length to operate correctly, a hanes manual will teach u how to set it correctly at the correct length, the IAC controls idle quality etc... if it doesnt run at all it could be alot of things, u need to check for fuel, spark, and go through all the lil things before u can just conclude its the IAC. try to run the car with the MAF unpluged... see how it idles, even with it unpluged it should run but very rough and like crap, then plug it in and try the IAC... also try giving it gas and see if it works etc, then check fuel, spark, unplug the ECM and check timing etc... has it always had this prob? or is it recent?

 

Have you checked the timing? To make sure it isn't horribly off?

And did you take the iac apart to clean or what? Soak it in carb cleaner or something?

 

the problem is recent, at first if i unplugged my maf the car would run but very very rich and the idle would be ok, there was a vacume leak at first which i fixed, i did have a whole bunch of codes pop up 32,33,34,36 but now i managed to get rid of them and they halvent shown up since, i halvent touched anything timing wise, when it does run i can keep it running for a good while. initially i had to take the intake ductwork right off the get it to run but it did run, i had it on the road for a bit and it ran good once it was over 1200rpm, there is something wrong with the idle i think this because sometimes i would be at a light and all a sudden it would just die on me. i have asked some of the mechanics at my work and 1 said IAC im still not sure what to do, i went and took mine out and cleaned the crap out of it but it didnt do anything what so ever

 

Did you clean the passage inside the throttle body too, where the IAC goes?

When I did - all kinds of junk ran out of there.. after that, I could start it without gas 70% of the time... So I might pull the throttle body off, make it sparkle and get a new IAC.

 

i think im going to buy an iac right now, i cleaned the old one, clear the entire throttle body passage included and yet it doesnt idle unless i have my code reader plugged in which i guess fools the ecu so that it will run, when i cleaned my old 1 i did notice that the spring stayed under tension even when i took it out and when i cleaned it, so this might be the problem cuz it would shut down at idle every now and then for the 3 years i have had this car

 

ok IAC isnt my problem, it helped a bit but isnt the main cause. i dont throw any engine codes still and i dont know what else i can change for the heck of it i checked the reading at my injectors and they all read 15.88(their the ford svo 24) and i got the injectors new, im pretty sure this problem is computer realated cuz when the code reader is in, she will run and drive, when its not well just dies. does anyone please!!! know how this can be fixed i havlent tamperd with the timeing at all, the only thing i changed were the injectors and i placed new gaskets on all the ones i removed and i torqued all the bolts down properly. it still sounds as if i have a vacume leak somewhere around my air filter or it could just be the sound of the car struggling for air im not sure, its rough on idle but smooth drivingi got no idea whats wrong can some1 please help me

 

if it runs better with the reader in... go to the passenger side firewall and unplug the ECM wire that controls timing advance/retard... make sure the car is off and unplug it.. turn the car on and see how it runs at idle... this is when u check ur base timing as well. see if it runs better, shut the car off and plug the wire back... its a single wire with a connector mine was brown/black right above the blower motor. when the wire is unpluged its going to throw a code, and dont plug it back in when the car is still running, make sure its off. this will bypass the computer completely and more than ur code reader does... if thats the prob u might have a bad ECM.


just a stupid question... have u adjusted the idle adjustment screw? in the TB? u might have to adjust that if u havent for a higher idle, urs might just be too low.

i dont think its timing bc timing would be alot worse when the car is reved... id check the ECM by bypassing it and seeing what happens first.

 

Ill try that soon, been checking over a few things got a buddy comng over tommorow who is a GM mechanic to help me out. just wondering is you have to adjust the tps and the iac every time u remove the throttle body from the plenum?