Is it normal for the engine to konk-out if you disconnect the AIC plug?

 

Idle air control IAC? If so, then yes, it's pretty normal.

 

Its actually a sign that your engine electronics are doing their job well. If you unplug it, the engine should not run right. If you unplug it and nothing changes, then the IAC is probably bad.

 

knock out as in you mean die? AIC?? do you mean IAC=idle air control valve or AIT=air intake tempature for the IAC it should stay running but it will be low rpms and with it pluged in it should idle around 900rpms, with the AIT unpluged it should still run but shouldnt run good and will throw a check engine light

i have owned many fords especially trucks and they still idle with the IAC unpluged but very low around 500rpms, one truck did die if i unplugged it, it also depends on what rpms you base idle is set at

 

Good, cause thats what it did. -thank you.

 

Ive been messin with one for two days now, and Ime now forcing it against its will to run correctly.
-I asked if the AIC,-(sorry, im gettin nutty from dealin with this) IAC unplugged, would make the motor die out because I have a High Idle problem all of a sudden, -i unplugged the IAC and the idle came back down where its normally been, and i drove it..it acted fine, but i knew it wasnt right doin that, so I plugged it back in, and it rose to a higher RPM again, at this point i backed off the dead stop screw on the linkage and the idle dropped until i figured it was low enough to where it was before, and.. then i unplugged the IAC just to see what would happen, and the motor died, and I heard the small clicks over where the computer is.
I plugged the IAC back in, started it up..its at the low idle now that i set with the dead stop screw, but, the "Check engine"light is still on.
I got two brand new IAC'S and Im having the same problem with both of them,..Mabey its not that? this originally started out with changing the TPS and I got ambitious and cleaned the Throttle body,Plenem opening, everything was fine till about 8 min into it warming up and BAM check engine lite, and high Idle.

 

What is your closed throttle TPS output voltage? If the new IAC's act correctly, it must be something telling the computer to open the IAC, possibly a misadjusted TPS. Also, what codes are coming up for the check engine light?

 

Ok, here we go again.

That dead-stop screw, is just that. All it is for is to stop the throttle plates from jamming in the throttle body. It's a mechanical thing ONLY, and should NOT be used to adjust idle. Idle should be controlled by the holes in the throttle plate, and the IAC.

Your CEL (Check Engine Light) is probably coming on now because you have low TPS (throttle position sensor) voltage, now that you've backed the screw out, thus letting the throttle rotate further closed. Pull the codes as described in www.fordfuelinjection.com to make sure, though.

Your initial high idle problem is probably caused by a vacuum leak. Here's how that works. Lets say, umm, the plenum gasket starts leaking. (See my gallery) Ok, the air goes in, and makes the engine stumble a little because of lean mix. O2 sensor says "HEY! LEAN MIX!" ECM says, "Injectors, turn on a little more to make the mix right." More air + more fuel = more RPM. Meanwhile, you have some cylinders running rich, and some running not so rich, which will most certainly cause some vibration, if not a dead miss at times, depending on throttle position and engine load.

Dig around through the posts, and there's lots of help with troubleshooting fast idle and lean miss and vacuum leaks. I know, I've put a lot of it there. When you start hunting for leaks, I recommend using propane. It doesn't pool, and isn't as likely to cause a fire as liquids are like starter fluid or carb cleaners. Liquids are a great way to find out if you have leaky plug wires too, the HARD way. Even if the propane ignites, there will be just a quick flash, and it's over. You might singe your eyebrows a little, but that beats the heck outta melting your face, or burning your truck to the ground.

I preach safety in here, because I see too many suggestions that indicate the poster of the advice has never seen a serious fire. I've put out a fuel fire on my VW from a broken fuel line, and it wasn't easy and did a lot of damage in a short time. Advice, however, is worth exactly what it costs, especially if you don't use the good stuff. Lots of brilliant DIY mechanics in here, but a few of them like some techniques I find quite alarming, if you'll excuse the pun.

 

I have a question about adjusting the tps. How is it even done? I mean, there's two screws, one on either side.. how are you supposed to adjust that? I don't think that's my issue because my idles all over but yeah..

 

Loosen the screws and twist the TPS until the desired voltage is reached, then tighten the screws.

 

Ok, and that's how I've read it in multiple places.. but it's not like there's notches for the screws to move within when loosening them? It seems like it can only go on one way?

 

Some throttle position sensors are non-adjustable, but to make them adjustable, just get a drill and ovalize those holes to permit a little bit of rotation. Have you check the closed throttle TPS voltage to know if it needs to be adjusted?

 

wow ..... alot of you guys are mis-informed .

The idle stop screw .... is there to adjust base the idle. Then you plug in the IAC and the computer will adjust the idle higher if it feels necessary . Like if you have the AC on , or turn the steering wheel .... it will raise the idle momentarily . Its job is to let more air in .... which raises rpms .... ( yes folks its air that makes a engine run , not gas ) the gas is needed to make the combustion occur ofcourse , but for high idle problems , you have a vacuum leak of some sort getting in there .

Now for the TPS . You adjust the TPS *AFTER* you adjust the base curb idle .

Take your voltmeter ... put on DC volts , and shove the leads into the green and black wires . Crank the truck up . You should see .890 volts or so if its close to being adjusted right , tops .980 ..... 1 volt and higher ... you need to loosen the screws on the TPS and move it slightly to lower the voltage (it dont take much ) and tighten screws .... test again .

If you test the black and orange wires ... you will see 4 - 5 volts always . Thats the supply voltage . The .890 voltage is what the sensor is telling the puter . Its saying .... hey .... we are idling . Once you move the throttle .... you will see the voltage go up slowly .... its saying .... hey .... we need more gas and timing here !

 

umm ... actually .... read my post above . In fuel injection class you learn how to adjust the curb idle . Most people are scared of the * evil forbidden throttle screw*


Well you are mostly right . Yes air with the addidtion of the proper mix of fuel .... makes rpms rise .

But soon as you crank up an engine ... the 02 sensors are ignored .... Until ..... it goes into closed loop ..... which is around 160 degrees . Until that point the 02 can holler all it wants , and it will be ignored . The engine is running on a chip that is burnt to a program for use only in open loop , to give the proper fuel on a good running engine . After it goes into closed loop .... the computer will then take ignore the chip , and take ideas from all the sensors and start using look up tables ( another chip system ) and if needed will change outputs .

As for different cylinders missing .... yes it depends on where the air leak is . You have a throttle body gasket leaking ... all cylinders will pretty much get the same amount of extra air . It will be like opening the blades a tiny bit more . Rpms will rise , and the engine will be smooth for the most part , maybe a little rough , maybe not . The computer then sees all this air .... and yet the TPS says its idling .... hmm .... it throws a code that the TPS is bad . ( its not bad ) You have a lower intake leak on the other hand ... that one cylinder will be lean , and therefore wanna run poor and shake n rattle .

One sure way to kill a 02 .... or a TPS .... is clean the TB with carb cleaner . That cleaner pools up inside the TPS and it really dont like that .... and the 02 .... its going bye bye sometimes .