Is my IAC bad?

[Sk8er07999]

Ok my idle is shit. Before everyone starts saying try search or go to vfaq let me tell you I already have. I printed the vfaq IAC testing page and did the tests. All three coils where tested with the IAC at room temp and all read around 30 ohms which is spec. But the part where it says to connect a 6 volt battery and you should feel movement I don't. But I can hear a slight clicking. I tried this with several different batteries and I can barely hear a click. I mean you have to practically have the IAC in your ear to hear it. So my question is. Is this normal? Or should I physically see the plunger pop in and out and feel movement? I tested an IAC the other day for a ford ranger at work and that thing popped in and out and there was no doubt that thing was working. Should I see the same thing with mine? I am almost 100 percent sure it's bad but I just want a few others input. If it's bad anyone have a working IAC for sale? Know what year of cars I can get one off that will work on mine? Thanks for the help. Kevin.

 

[joeym4130]

Did you try just taking the ISC out of the TB, leaving it connected, and looking at it as a friend turns your key to on/off?? Its supposed to adjust itself and you can see it move in/out.

 

[Sk8er07999]

No I haven't. I will have to try that today.

 

[crankbender]

Yeah that is the best way. Also apply light pressure to the top of the ISC and see if you feel a weak spot.

The faq on this does not explain very well that the ISC is a stepper motor. That means that as you apply the voltage the motor goes through like 1/3 of a revolution....then you have to apply the voltage to the next step and so on. About 20 steps later you may be able to see the movement...

 

[Sk8er07999]

So your saying this thing is barely going to move right? I haven't had a chance to do the test with a friend yet but I will maybe tomorrow. So lightly depress the end of the iac and have a friend turn the key on right? I should feel it slightly move right? Thanks for the help.

 

[crankbender]

No when the ecu is used to test the stepper motor (in the car) it will cycle through the coils very fast and you will see/feel it moving up and down. When you do it by hand with the battery it is barely noticible when it moves.

 

[Judacoth]

Well, we don't know if its bad yet.
Are all 4 coils to spec? (resistance check)
Is their confirmed movement? (keyswitch check)

If the answers to the above are yes, then what is the problem?
Is it surge?
Is it low idle?
Is it no idle up on A/C?

There are valuable resources available that discuss this subject to the ultimate level.

However, nothing would be more valuable then hooking your car up to a proper scanning device.

 

[Sk8er07999]

Originally posted by crankbender
No when the ecu is used to test the stepper motor (in the car) it will cycle through the coils very fast and you will see/feel it moving up and down. When you do it by hand with the battery it is barely noticible when it moves.

Cool ok yeah because the battery it doesn't move at all. Judacoth did you read the whole thread? If you did you would have known that each coild was tested and all where within spec. The only thing I had a question about was how much movement I should see when hooked to the battery. What type of scanning device? I have an actron obd II scanner at work and really nice scanners at school. I will be learning all that stuff this week and next at school. Last week we used the snap-on vantage, fluke 97 and 98 digital storage oscilliscope to check tps output voltage as well as injector on time. This was also the unit that I used to check my IAC's resistance but didn't have time to do anything else with it because I wasn't even supposed to be doing that. Symptoms are the car starts and runs fine. except in the morning it idles like I have hks 272's and almost dies. But when the car is hot it wants to idle smoothly around 2000 to 2500. If I unplug the iac it while car is running it has no affect on the idle what so ever. So I am almost 100 percent sure the IAC is bad but I just need this last test to be sure. Thanks again guys, Kevin.