How to: IAC valve cleaning thread (w/pics)

[AtlantaViking]

If your issues are occuring only at idle and once going the truck seems normal - it sounds like the IACV could be the likely culprit. I don't know the 92 engine well but if it has an IACV, pull it off (its simple) and check that the motor is still good with an ohmmeter. It should be about 10 Ohms both ways. Then make sure that the motor isn't shorting on the housing by using the meter again: One probe on a terminal and the other probe on the housing. It should be an open circuit. Do the same thing on the other terminal and it should also be open.

In my case the motor was fine but the actual valve assembly was all sludged up and was likely stuck. You can try to flush it as others have using their suggestions.

If the engine is rough at places other than idle than IACV is not the likely cause. This thing is specific to idle only.

Good Luck.

 

[powerwagon]

well i have had some idel probs hear lately on my 88 2.3 it idels fine around 900 to1100 but when i rev the engine and let out it drops to 500rpm, stumbels and climes back to 900/1100 rpm? is this my iac? can i use carb clener or throtel body clener?

 

[99XSP]

Well, I'm done with my Explorer.

The issue with the erratic idle is present again, and worsened. I just got back from a short trip. The truck stalled on me while sitting on an intersection. I was able to restart it, it did it again and again. It seems that every time I had to start it, I had to crank even longer than before.

I didn't want to take a chance and "drove" it home. How embarrassing moving like that. Didn't even have to turn it off, it stalls when coming to a full stop. Somehow convenient.

I have replaced all parts mentioned on here (all with original Motorcraft), spent even hundreds of dollars on new O2-sensors :fire:. I have no service lights, both readouts do not report any error codes. I have more important and valuable things to spend my money on.

Neither my shop or 2 different Ford dealerships are able to fix this persistent issues. It is still the same it was when I got it 2 years ago, despite all the new parts.

BTW: Did I mention that I put a battery in my backup car and it fired right up? 17 years old, not driven since November last year. No issues.

 

[jayjaylenhenson7]

Could it be something as simple as a faulty fuel pump ground or a clogged fuel filter??

 

[99XSP]

Theoretical.

Which would mean of course that a new fuel filter is clogged right out of the box, and 3 places who all claimed (and charged) checking the wiring did either not do it, or didn't catch a fault.

That's the chance you always take, and might be something were someone is getting a deal.

Greetings!

 

[tokelokenem]

Hello, I have a 1998 Ford ranger XLT 4.0 v6 121,000 mi. Recently the truck jerks forward and back when i accelerate. Also sometimes it has low idle. What are some parts i should check or replace? Would cleaning the IAC help these problems?

 

[Tony H]

Hello, I have a 1998 Ford ranger XLT 4.0 v6 121,000 mi. Recently the truck jerks forward and back when i accelerate. Also sometimes it has low idle. What are some parts i should check or replace? Would cleaning the IAC help these problems?

My explorer got very sensitive when the Ignition wires hit about 90K miles.
If it does this when the car is under a Load, like accelerating, Maybe it's time to replace the wires.

 

[tokelokenem]

My explorer got very sensitive when the Ignition wires hit about 90K miles.
If it does this when the car is under a Load, like accelerating, Maybe it's time to replace the wires.

Ok ill check it out thanks. Also when it shifts from 1st gear into second, it feels alittle hard or forced. Its a automatic.

 

[Hoof_Harted]

Great post. Thank you for the write-up and pics. I was having these exact same issues, followed directions, and started up and ran perfectly. Thanks again. Great forum!

 

[tonydp]

would my 02 4.0 be under the cover, the actual piece that hold it on? If i disconect it the truck won't start correct?

 

[expeditiousman]

Well, it has been a few weeks now. So far, my issue is gone. There were a few times when I noticed that the rpm was about to drop, just for a split second, but immediately stabilized itself. So I consider it fixed.

However, now I suddenly have the idle being rough once in a while while sitting at a light, with the air distribution selected in any mode in which the a/c compressor would turn on in warmer weather. No negative effects if turned to vent or floor only (as the compressor would not turn on, regardless), also if turned to "Off".

My long trip to MI resulted in 16 mpg, excuse me? Driving around city, well, this morning my odometer showed about 85 miles, and the fuel guage being half. My past calculations (I keep a steady track and always top off) shows about 10 mpg. Unacceptable :thumbdwn: for a vehicle being EPA rated 15/20.

I have to check with my dealer what that could be. That needs to be fixed, for a reasonable price. If not possible, I'm ready to dump the vehicle. :roll: It's like a piggy bank, I keep putting money into it, and hardly get any benefits.

Greetings!

what kinda maniac driver are you. i am getting 14.7 mpg driving mostly city miles.
the only problem i have with my car is that for some odd reason usally the idle speed is 500 rpm, and driving rpm at 35 mph is usally 1500 rpm, but from some reason, it jumps to 1000 idle and 2000 rpm at 35 mph. the only think i tested is while driving turning on and off overdrive, dosent affect the rpm when its running "higher then normal", but then sometimes like today driving back home, it just goes back to normal outa nowherer :/ cant seem to figure this one out. can i can say i get good mpg :

 

[xdviper]

Transmission not changing gears quickly to match the speed? You can tell when I hit 35mph, it changes to third gear and drops the rpms to 1500 like you said.

what kinda maniac driver are you. i am getting 14.7 mpg driving mostly city miles.
the only problem i have with my car is that for some odd reason usally the idle speed is 500 rpm, and driving rpm at 35 mph is usally 1500 rpm, but from some reason, it jumps to 1000 idle and 2000 rpm at 35 mph. the only think i tested is while driving turning on and off overdrive, dosent affect the rpm when its running "higher then normal", but then sometimes like today driving back home, it just goes back to normal outa nowherer :/ cant seem to figure this one out. can i can say i get good mpg :

 

[expeditiousman]

Transmission not changing gears quickly to match the speed? You can tell when I hit 35mph, it changes to third gear and drops the rpms to 1500 like you said.

well it only happened a few times. and now it been normal agin. the only reason for my consern is my mpg when it happens i get around 4 mpg less, at least instantly, and i can get the gear to change at 25 ish mph to about 1.1 rpm, then i slowly speed up to 30 or 35 usally, but i stay in that gear getting about 20 istant mpg speedin up to 35 mph then about 28ish mpg instant going constant speed at 35. but i like my ford, havent had many problems at all fortunatly

 

[47knuckle]

mine howls like crazy on a hot or humid day when idling. i think its embarressing when going through town and hitting red lights and my truck sounds like a constant moose call. i took a look at my idle valve and it was dirty. i hope thats what it is. i put it back on for now till i get electrical cleaner. i guess it only does it when the air is very thin. thats the only time it does it and it idles lower than normal weather.

 

[318EDDIEbX]

.i have a '96 eddie and i have the same symptoms as all of u but the noise seems to be comin from my fuel pump...i have a slight choppy idle and it seems to be lackin a lil power at high rpms...when i change out the iac what all does it take to complete a full engine cycle to pull up the correct codes?

 

[dannyces]

hello all
ok so i pulled and cleaned my iac on tuesday nite and holy cow was it dirty. i never had any whine but it would have a real bad dip in idle when it was in gear down almost to the point of stalling. it no longer dips down that far it does alittle but no where near as much. now the problem is whenever i start it, it idles real high like almost 2000 and then slowly settles down. so my question is did cleaning this make something else out of wheck and if so any ideas on what i could do to even out the idle
Thanks
Danny

 

[anth2c]

what if it has no spring in it? i replaced it with one that had a spring. it idles really fast but the round part below the spring is broke off. would that being broke cause the fast idle. and what aobut the one with no spring will that effect anything?

 

[Scooz]

I have a 94 explorer XLT. Just yesterday i replaced the valve cover gaskets and plenum gasket. So i drive it home and first it sounds like theres a bit of a hole in the muffler. Now i know it doesnt, but thats the sound it gives off. So, ok, not bad. I drive all the way home, park, and when i put it in park the idle revs up to 3k. It does it when i start it and when i shift into gear and back it still does. Now im going to stop shifting it so i don't ruin the trans, but do you think it could be the IAC valve? Maybe some more dirt got into yesterday or its not on correctly? I checked all of the vaccum hoses

 

[RupertExplore]

'99 Explorer OHV 4.0 L. The main issue was a slow cold start. It would turn over fine, but do so a few extra times before it started. It also ran slightly rough for a few seconds after start up.

I cleaned the IAC valve with electrical parts cleaner and a Q-tip (carefully, I recommend it). The first start up (happened to be a cold start) was as before (slow). The second cold start was perfect!

 

[6AM]

I've had a bad idle on my 2001 Sport for years. It's started stalling recently. It seems to be stalling a lot when after driving I put it in park. Stopped in drive hasn't been a problem. The RPMs will often fall to the point of stalling at start up. Sometimes it will immediately stall if the car was recently driven.

Right now I have a check engine light for ERG airflow insufficient. I've cleaned the ERG valve and sensor as well as the IAC valve with little to no affect. Everyone keeps talking about "moving the IAC valve". I see nothing that can move in the IAC. Perhaps mine is stuck and needs to be replaced? Could it be the ERG valve that's causing a rough idle and occasional stalling?

Thanks!