how to tell IAC is going bad?!?

[SwaintaN]

Ok so how do you tell when your IAC is going bad or not? i was told that my idle problem might have been that because its not 100% even after other things were replaced, no codes to pull, just trying to figure out how to tell before dropping money into it if its still good

 

[Roadrunner777]

A very rough test would be to start the engine, idle, and unplug the IAC. If nothing changes, then it is suspect. Also, if you remove and clean it, the valve spindle should move freely. I'm looking around for coil resistance values; I'll post them if I find them.

 

[SwaintaN]

I did that, is why im asking. After painting everything and reinstalling everything, while the motor was on, i pulled the sensor plug and it was a very very very little change. so i thought i would ask. i mean hell the sensor is from 1993

 

[SwaintaN]

Ok so reconnected it all from a previous task.. and let it idle for a few mins then yanked the sensor plug out of the iac and it dropped badly to the point of stumble, as soon as i put it back on it surged up and then settled back down to where it orig started. so guessing that is good..

while i was looking at it i thought about the 50 horsepower for 50 cents trick, mine still opens all the way since i cleaned it all up last year.

 

[Currency]

Sounds good then, perhaps you have another issue?

I use carb cleaner on my IAC, making sure it dries before starting it again. I have cleaned mine twice in two years. Overtime it idles higher overtime, perhaps I should replace it sometime soon but right now there is no real need too. My RPMs sit are 600 at idle, after 10 months or so it will slowly climb up to 900 and sometimes higher.

When I first got it, I was at a complete stop, then drove 1.8 miles with neither foot on the brake or gas until I reached a stop sign, After searching on here I cleaned it and she slowed down a bit. Saved gas too.

 

[SwaintaN]

in park mine sits at 900, in gear itll sit at 600-700

 

[Currency]

Mine is around 600 in park, same in gear as well. If you have not cleaned the IAC, pull it off, three bolts, watch for the gasket and plug so you do not break the clip. Once apart remove two screws and spay with carb or injector cleaner. Let dry, 20 minutes under the hot sun.

Then bolt it back up. It's easier than changing the air filter in my moms Dodge mini van. Have more crap to remove to replace her air filter than you do on every vehicle I've changed air filters on before. Crazy

 

[Roadrunner777]

What else have you looked at and/or ruled out? Obviously, you have reset the PCM to learn idle. Vacuum leaks? MAF good? Leak in MAF/TB tube? Good plugs/wires?

 

[SwaintaN]

Currency i know the feeling, the Chevy Venture my wife has, you have to take out almost the whole right side of the motor bay just for the filter, drop the motor just for the plugs in wires.


I have no leaks, wires n plugs are good. My codes are for the 02 sensor, but i figure that is cause of 2 things.. 1 the snorkel and 2. the bad/broken exhaust. is a 900 idle in park normal? and is a 6-700 idle in gear normal?

 

[Roadrunner777]

My 94, when the engine starts, it runs a few seconds at about 1,100, then over about 3 seconds, drops to 600. It's about 600 in gear too.

 

[Currency]

Sounds like your running a little rich for some reason. The codes my explorer throws out are also for 02 sensors, I still have not changed them. Just jiggled them a bit here and there and it seemed to run a little better.

I also get a code for MAF, have cleaned it several times as well. Figure I dont have $100 for gas, let alone a $100 for a new MAF.

The codes I get from my 02 sensors says mine runs lean. I personally see nothing wrong with how my explorer runs or drives other than alignment issues therefore I have yet to fix the MAF and 02's.

Edit: yeah mine idles high for a few seconds on start up as well. I consider this normal since every vehicle I've driven does this.

 

[WVUexplorer]

So i had the same problem just a few months ago in my 92 explorer. The car was idling rough and it was throwing O2 sensor codes and MAF codes. It turned out it was 2 problems first the MAF was bad. if you unplug the MAF while the car is running rough it should run smoother. Another thing is the tube going from the MAF to the throttle body (the one that says "caution fan") was cracked on the underside. This tube is notorious for breaking and is pretty expensive ($130). so remove the tube (2 hose clamps) and thoroughly inspect it for cracks and leaks. if it is cracked it will cause a lean O2 sensor code to be thrown. And if cracked, duct tape will work for a bit until you have enough money to buy a new tube.

 

[SwaintaN]

tube going from the MAF to the throttle body

talking about the intake hose? thats the only one (on mine) that comes from the maf to tb, those are to terribly expensive, can get em at junkyards and/or build your own with the really helpful thread on here..

 

[WVUexplorer]

Ya that's the one i was talking about, luckily for me i work at a place that can get the part "cheap" but once i replaced it all the problems were solved.