question about the iac

That black knob is a cover for the IAC's air intake. The IAC is not adjustable. The throttle body has the idle screw that is for adjustment of idle. First things first return the no name IAC valve and buy a Ford one or it will be bad in a couple of months. If you do feel that you need to adjust your idle then do it this way:

You will probably get a million different responses on how to do this. This is how I have done it and it works for me. And I've done it a lot.

1. Disconnect the negative terminal to your battery and turn on your headlights for about 10 minutes(there's a lot of speculation as to how long. some people will even say to disconnect the positive terminal and some people will say to leave it disconnected over night.)

2. Disconnect the wiring harness connector to the IAC

3. Turn off headlights and reconnect battery. DO NOT TOUCH THE GAS PEDAL!!

4. DO NOT TOUCH THE GAS PEDAL!! Try to start the car. If the car won't start adjust the set screw on the throttle body a 1/4 - 1/2 turn and try again. Repeat until the car will stay running. It will run rough but that is what you want.

5. Let the car sit and idle (DO NOT TOUCH THE GAS PEDAL!!!) until the car reaches operating temperature.

6. DO NOT TOUCH THE GAS PEDAL!!! Step 5 allows the computer to relearn idle settings. It's pretty cool when you follow my procedure because you can actually hear and feel the car figuring out the proper idle settings. It will go from idling rough to idling smooth as it warms up. Once the car is warmed up verify that the car is idling at around 700rpm. If the car is not idling where you want it, adjust the screw until it hits ~700rpm and then let is sit maybe another 10 minutes DO NOT TOUCH THE GAS PEDAL!!!

DO NOT TOUCH THE GAS PEDAL!!!

Turn the car off. Reattach IAC wiring harness. Now remember we adjusted the set screw on the throttle body. That means that the voltage reading from the TPS sensor has changed. It should read between .96 and .99 volts. Anything outside of that range will cause all sorts of issues including misfires and rough idle.

7. You will have to back probe the TPS connector. With the connector attached to the TPS stick a paper clip into the rubber boot on the connector where the top and middle wires go into the connector. The rubber is very flexible the paper clip will slide in between the rubber and the wire.

8. Set your multimeter to volts. Turn ignition to ON. Then place your multimeter leads on the metal pins. If it comes up as a negative that is okay as long as you are -.96 to -.99. If you get this reading then great you are done and hopefully your issues are gone. If not proceed to step 9

9. This is where and extra pair of hands come in handy. Using a large screw driver you will need to loosen the bolts that hold the TPS. DO NOT USE A SCREWDRIVER THAT IS TOO SMALL BECAUSE YOU WILL STRIP THE BOLTS. They probably will be really tight so you have to really lean on the screwdriver and use some finesse.

10. Once the bolts are loose you will need to move the TPS up or down and continue to read the voltage. Once you get it to the desired setting you can retighten the bolts. What I do is I find .97 and then as carefully as possible I tighten the TPS down. what will happen is the voltage will change usually to .96 or .98 but that it okay. Once you are done with this manually open the throttle body a few times and close it then reread the voltage and make sure it is still within our desired range.

11. Depending upon how loose your set screw was you might want to cover it in RTV to hold your setting. At this point you have CORRECTLY reset you idle.

you should not have to adjust your idle ..



The older EEC IV cars ( up until 1995, 1996 and newer are EEC V) were sensitive to TPS settings.. The EEC V cars not so much..


You got a wiring problem causing all those faults.. replacing all four of those components won't fix a thing. 1 of them might be bad but not all four..

If you have the exact code numbers I can help you

BigB9646 said:

well i took it to a dealership they just gave a sheet with the problems like

replace the iac

replace the egr

replace the dpfe

replace the canister purge valve

dont have the codes man

Click to expand...

Whoever worked on your car sucks..

Not all techs are created equal and whoever this guy is should know 4 components are not going to go bad at the exact same time.