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Does your car idle poorly, have a rough idle, or in general have an idle problem? Learn how to fix a car with high or low idle, and learn how to fix a car that idles up and down by cleaning the idle air control valve. The IAC valve is what keeps the cars idle at around 800rpms. If you turn the ac on and it idles low or your car stalls at lights or in reverse, or your car shakes at idle, this video can also help!
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The OG Idle Air Control Valve Cleaning video (7yrs ago):
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Hey guys chris fix here and today, i'm going to show you how to fix your car if it's not idling properly and we're going to be doing that by cleaning the idle air control valve. This valve regulates the air going into the engine at idle. It maintains your idle, which should be around 800 rpms or so. The problem is this valve gets clogged up by carbon deposits, which could keep the valve stuck open or stuck closed.

Therefore, messing up your idle, so in this video i'm going to show you how to clean this at home very easily. All of you guys will be able to do it after you're done watching the video, and i have two perfect examples of how to do this. First, we have the drift sting which has a high idle. Let me show you all right so clutch in we are in neutral and let's start up pay attention to those rpms and you can see the engine.

Rpms are about 14 to 1500 rpms, and that is way too high. Now, normally, when an engine starts sure it might go up to 500 rpms, but after about a minute, it drops down to around 800 rpms. This never drops down, even if the engine is fully warmed up. You drive around for 10 minutes.

The rpms stay high, like that, and that makes me think that it's a dirty idle air control valve and it's stuck open allowing too much air in which keeps the idle high. And even if i rev the engine up and let the idle drop down, it still stays at 1500 rpms, which is too high. So that is why i think it is a dirty idle air control valve now. The idle air control valve could also cause the engine to idle low.

Let me show you that in the pickup truck so now, i'm going to start the truck and watch the rpms and, as you can see, the idle is incredibly low. If you press on the gas it revs no problem and feels nice and smooth, but once you let go, it drops down the engine shakes and it almost stalls so right away. It's making me think we have a dirty idle air control valve. That's stuck closed.

It's not allowing enough air to the engine which is keeping those rpms low. Now other symptoms you might encounter are, if you put a load on the engine, the rpms fluctuate, they drop down, they almost stall the engine, for example. If you turn the headlights on that puts a load with the alternator that could cause the rpms to drop or flutter. If you put a load with the air, conditioner compressor turn the ac on.

That could also cause the rpms to fluctuate and flutter, maybe even stall. The engine turning the steering wheel, if you have power, steering, could cause the rpms to fluctuate, putting the car in reverse. Maybe you throw it in reverse and it stalls or you put it in drive and it stalls. If you have any of those symptoms, there's a good chance that your idle air control valve is dirty and it's worth giving it a clean to see if it alleviates those problems.

So now you have an idea of the symptoms of a dirty idle air control valve. Where is this located, so you could remove it and clean it? Well, it's actually usually pretty easy to find what you want to do. Is you want to find your air filter box? This is where the air filter is that cleans the air coming in, follow the intake tubing and go to your throttle body and right away. You can see your idle air control valve right here.

This is also known as an iac valve or an air bypass valve. Whatever you want to call it, don't worry, i'm going to show you how to clean it properly without damaging the valve and without damaging your engine. So that's where it's located right here. Sometimes it's located to the side.

Sometimes it's located underneath or maybe it's a little bit back here on the intake manifold. You just want to look in this general vicinity around the throttle body. Now, let's check out the mustang real quick again, you want to find the air box which is right here and then follow that intake tubing to the throttle body, which is right there and right away. You can see here is the iac valve now, if your car is more modern, like this 2014 maserati and uses an electronic throttle body, so a throttle body that doesn't have a direct connection with a cable like this.

So there's a motor in here when you press on the gas it sends an electrical signal right to this motor and opens and closes the throttle body. If you have an electronic throttle body. Like this odds, are you do not have an iac valve, because you don't need one? You have this, which could regulate your idle since it's electronic, the computer could say, hey open it up just a little bit and have the idle exactly where it needs to be. So odds are electronic throttle.

Body means you, don't have an iac and then you'll have to look for something like a vacuum leak. If your idle is fluctuating. So now that you know where to find the iac valve, let me show you how it works, because i think it's very important to understand how something works before you actually work on it. That way, you know why you're doing certain things such as cleaning it.

So i have an intake manifold here and here is the throttle body. We have the idle air control valve right on top and let me show you how this works, so the throttle body is what regulates the air going into the engine. If you just give it a little bit of gas, then it allows a little bit of air in and allows your car to accelerate. If you floor it, it opens that butterfly valve all the way.

Now, when you let off the gas - and that closes completely, how do you get air into the engine? Because you need air in here in order to keep the engine running? Well, that's where the iac comes into play, since the air can't get past that throttle plate. What this does is it allows air up in front of the throttle plate to go through this hole and back down into this hole which goes into the intake and it feeds the engine enough air to keep it idling at the proper rpm. So the computer tells this valve: hey open the valve up. We need more air or hey close the valve, because we have too much air and that's how it regulates the rpm and here's an up close view.

So you have a better idea of how this works. The air comes in right here and if the computer is saying hey close the valve, it lowers the valve and plugs that hole. If it says hey, we need more air, it opens the valve depending on how much air it needs and it'll let more air in so over time. That valve could get clogged up, for example, check out this iac with 300 000 miles on it.

You can see the valve has carbon on it, which could prevent it from closing all the way. Also, the valve stem over here has carbon deposits on it, which could really gum it up and make it stick all right. So now that you know how this works, let's go and clean it, and it's very simple. First, let's get our safety glasses on, so nothing gets in our eyes and all you're gon na need to clean.

This is some type of intake, throttle body or carburetor cleaner. Anything like that that could dissolve carbon deposits either of these will work and if you do have some type of brush a toothbrush, a pipe cleaner. Anything like that to get in there to get that carbon agitated will help very much. You don't necessarily need to have a gasket, it's super inexpensive.

This was like two bucks, it's good to have when you reinstall it that way. You know for sure you don't have any vacuum leaks and then finally, you're gon na need some type of socket set. Very simple: let's go and remove our idle air control valve. So first we need to unplug the electrical connector from the valve.

Then there's two bolts that need to be unscrewed. So, let's break the first one loose and unscrew it the rest of the way. Good then break the second one loose and unscrew that the rest of the way, and now the idle air control valve can be removed. The last thing to do is to tape off the opening that goes into the intake, so no dirt or debris gets into your engine beautiful, and it really is that simple to remove the idle air control valve and it's even easier to clean it.

Now, let's remove the iac from the mustang, and this is a similar process. Unplug the electrical connector then remove the rubber intake tube, and now we can remove the two bolts holding in the iac starting at the top good and to get to the bottom one. I'm removing the pcv hose and now we can unscrew the bottom bolt with the bolt removed. Now the iac comes right out and the gasket fell off.

So, let's get that as well and then finally tape off the hole so no dirt or debris gets into the engine all right so now that we have both of the idle air control valves removed. Let's go take a look at how dirty they are starting with the truck. If you take a look in here, you can see the carbon deposits which doesn't look that bad, but you can definitely tell it's dirty. Also, the valve looks like it's stuck closed.

Yep. Would you look at that? The valve was stuck in the closed position and that's definitely why the engine was idling so low. Now, let's take a look at the idle air control valve on the mustang and it's a little bit different. The air comes in through here and it exits through here and looking at this valve.

It also has some carbon deposits on it, but it doesn't look horrible, let's check the other side, and here you can see, there's some deposits on the valve shaft, which could be causing it to stick open alright, so you got to see how dirty each of these Are you got to see how each car idles with them now, let's clean them and see if we could fix the idle and the most important thing when cleaning this the number one rule is to always keep this motor facing upwards? If we face it upside down - and we spray in here liquid - could go down the shaft into the motor damaging the motor. If we face it upwards and you spray it, no matter how much you spray liquids not going to get up into that motor and you won't damage it so remember to keep the motor facing up now. So we don't make a mess. I have a little catch.

Can and i have a glass jar that way as we clean. We could empty all this into here and see what dirt and debris we removed and i'm going to be using the most common cleaner that i think most of you guys might already have, and if not it's easy to get this i'll link it in the description. It's just throttle body cleaner, you could also use carb cleaner. Anything like that will work, and all you need to do is spray.

The inside of the valve and use the pressure from the spray to knock loose any of the carbon and force it out of the valve, and you can see the liquid coming out of the bottom - is black instead of clear, which means we're cleaning the carbon out. Now to more thoroughly clean, this grab a thin pipe, cleaner and just clean as much as you can poke around in there on the top cleaning. The surface of the valve also clean the bottom as well, and, finally, give it one more spray to flush everything out and that's all there is to it now check out how dirty this liquid is. It should be clear, let's spill it out onto a clean towel, and it just turns that towel black and you can see all the carbon we removed from the valve and just take a look at that before and after so now that we got the truck iac Valve cleaned: let's move on to the drift staying and for this valve we're not going to be using any type of brushes, no pipe cleaners, no toothbrush.

Nothing, because i want to show you that even just spraying, it with the carb cleaner, will free this up. So just spray, the inside of the valve to dissolve the carbon and use the pressure from the spray to knock the carbon loose. Let's flip it over and do the other side as well make sure you get in there deep and spray at different angles. And again we aren't going to be using a brush just to prove that this will still work using only throttle body cleaner, and that is it.

That's all there is to cleaning it out just a couple seconds later and look at that, it's nice and dark. So let's check this out and you can see it's not as dark as when we use the brush, but there are still plenty of specks of carbon, which shows we cleaned it out, also check out the before and after picks. That is way cleaner. So now both of these are cleaned.

Obviously, the one that had the brush is a little bit cleaner, but again they'll both work. So now, let's go test them out now, just like everything else in this video installation is super easy. The hardest part is deciding whether or not you want to reuse your gasket. If your gasket comes off, what i would do is i would take a look at it.

I would see hey. Does it look like it's cracked? Does it look like it's going to leak in this case, this gasket looks perfect, so just put it back in place where it was make sure you line everything up now you want to make sure the mating surface is clean and smooth, and if there's any leftover, Gasket material or corrosion, you could use 800 grit sandpaper to clean it up, but this is good, as is so. Let's align the idle air control valve and hand, tighten it down all the way now use a ratchet to snug up the bolts a little at a time going back and forth evenly, tighten it down against the gasket. That way, we don't get any air leaks and don't over, tighten it because it's screwed into aluminum and that'll easily strip good.

Finally, let's connect the electrical connector so that you can hear it click perfect. So with that installed now, let's go start up the truck and see if she'll idle, properly all right moment of truth. So when you first start your car, your idle is going to be above a thousand rpms. That's fine! It should drop down slowly after about a minute or so and then eventually drop down below a thousand rpms and after about two minutes, our idle settled at about 800 rpms and there we go cleaning the idle air control valve fixed the idle in the truck.

She wasn't even idling above 500 rpms before this and now she's idling perfect. Now, let's go and see if cleaning the idle air control valve in the drift stand worked. So, let's remove the tape and then we can install the gasket and i'm reusing the old one, because it looks fine, there's no cracks or damage so get it aligned and then let's get the iac aligned and then tighten down the top bolt by hand. So it holds it in place.

Next, let's get the bottom bolt in and hand, tighten that as well and just like, before snug up both bolts a little at a time back and forth to compress the gasket evenly to prevent air leaks. Good. Let's finish up by connecting the pcv hose and then the intake hose and finally connect the electrical connector so that you hear it, click like that beautiful and that is all there is to it. Let's go test her out.

So, let's see what we got and she started right up, which is good. So, with the cold start, the rpms are about 1400, which is fine, and then that should slowly drop down just like that perfect and after a minute or so that'll drop down below a thousand all right and then, after about two minutes, the idol dropped all the Way down to eight to 900 rpms and she's idling butter smooth and with that we've fixed the idol in the drift sting. She is idling perfectly so there you go whether you have a low idle issue or a high idle issue, or your idle is bouncing around. That's how you clean your idle air control valve.

It's quick! It's easy! It's worth giving it a shot, even if you're not sure. If this is the problem, because it's that simple to do it could still be a vacuum leak somewhere an egr leak. Something like that. But again, this is so easy to do.

You might as well just see if it fixes it and in this case it fixed both vehicles, and this is actually a pretty common problem on fords, for whatever reason the idle air control valve gets dirty. This is one of my first videos. I've ever done on my youtube channel back in the day, i'll, be sure to link that video right in the side here and in the description. So you can easily find it if you're a fan of my channel definitely go check it out, because it'll show you the difference between the old videos and the new ones and how much work goes into the new ones and the editing and all that stuff.

I think you guys appreciate it, but as always, hopefully the video was helpful if it was remember to give it a thumbs up if you're not a subscriber, consider hitting that subscribe button and all the tools and products i used in this video are linked in the Description:.

17 thoughts on “How to fix a car that idles poorly (rough idle)”
  1. Avataaar/Circle Created with python_avatars Rust Underground - Workshop and Studio says:

    On a road trip through Mexico my Tacoma broke down in Nyarit, in a tiny jungle town. Local mechanic did this exact fix for us. Gave him 20 bucks and a buck knife for it.

  2. Avataaar/Circle Created with python_avatars Dave Z says:

    Thanks so much for another great video! Here's my experience!

    I have a 99 Cherokee Limited (XJ 4.0L) that was starting to show strange issues with rough idle, stalling, and RPMs fluctuating. It happened fairly randomly. I was worried there was a problem with the fuel system, but it was suggested I try to clean the throttle body and/or replace the IAC. Then I found this video and you identified the exact issue I was having with fluctuating RPMs, as well as common ways to trigger it. In my case, rough running or stalls would randomly happen during hard turns, the transmission shifting gears, or me shifting from P/R to D. I would also experience periods of very rough idle with low/fluctuating RPMs when in park, or stopped at lights. And on top of all that, I'd sometimes have trouble starting the car; I'd have to tap on the gas while cranking to get it to turn over.

    Your video finally encouraged me to stop being lazy and clean the IAC valve. I also went one step further and cleaned the throttle body; the XJ's IAC is a little awkward to remove by itself, and I had never cleaned the throttle body so it was long overdue. I just finished up and went for a ride around town – no issues with stalling or fluctuating RPMs whatsoever! Fingers crossed that it stays that way!

  3. Avataaar/Circle Created with python_avatars prod. Jaykll says:

    When my mr2 turbo ran, it had the low idle exactly like this and I never thought of the Idle air control valve. Changing the fuel pump soon as its busted so I guess I'll also order the IAC too and change that!

  4. Avataaar/Circle Created with python_avatars Bad habit says:

    Does this apply if the car revs up and down when parked or at a stop ? By rev I mean like how it sounds when people try to warm the engine during winter months. It's a 98 Accord and runs perfectly when moving but you come to an intersection I just revs up/down and everyone is staring at me like "wtf is wrong with your car" lol it's embarrassing and im by no means mechanically inclined but can't afford to take it to a shop.

  5. Avataaar/Circle Created with python_avatars Ghostking001 says:

    Hey Chris I changed my idle air control valve and even my egr on my 2002 Ford explorer with a 4.6 and I still have an issue, my explorer when it's warmed up and placed in either park or neutral will start to idle pretty high like 2000 rpm, doesn't throw any codes but I know that's horrible for the motor; Any ideas what it might be?

  6. Avataaar/Circle Created with python_avatars Mario Cubias says:

    Hi Chris I have the same mustang as u but just the 2004 one with the same engine 4.6 but mine idles at 3k which Ik is not good. I’ve replaced the iac,tps,maf and check for vacuum leaks and nothing. This all happened after I replaced the throttle body

  7. Avataaar/Circle Created with python_avatars roadstar499 says:

    i have a 2.5 l 2005 altima…had a different set up.looked like electronic unit on side of throttle body… i just took off plastic intake so i could open butterfly and spray gum out cleaner in mine… then i cranked motor a few times and it sputtered…then i put plastic intake back on and it idles very well now… it was bouncing up and down around 200 needle stays put at idle…fingers crossed it will stay fixed…thanks for sharing

  8. Avataaar/Circle Created with python_avatars Lucious Quinctius Cincinnatus says:

    Imagine me, a general diy'er, having a rough idle and gauging its probably my IAC valve. Thank God Chrisfix has a video showing you how to clean/replace. But wait, you have a 2003 Nissan Xterra. Your IAC is attached under the intake manifold, you cry as you spend the day trying to take it off.

  9. Avataaar/Circle Created with python_avatars Ronald Trujillo says:

    I own a 2000 mitsubishi eclipse 3.0l v6 and I was having a idle problem it would jump from 1000 rpms to 2500 rpms and now its has a hard time starting and if it starts it won't stay started for more than 3 secs … I had 4 codes MAF sensor malfunction IAT MALFUNCTION , 02 SENSOR MAP MALFUNCTION

  10. Avataaar/Circle Created with python_avatars Thomas Harris says:

    On an SUV Ford Expidition.. They are located where it is Hard too get at !!! Not easy !! It took me o er 3 hours to get it off. Plus I had to use a gear wrench to do the last part of it !!

  11. Avataaar/Circle Created with python_avatars Super Mario says:

    I feel this is incomplete … use your tool scanner to check the rpms 1st … to ensure the rpms … then clean .. then check the rpms with the scanner AGAIN … also .. the idle control valve is rare now a days since this component is now one big piece and part of the body throttle .. nothing you can clean separately …

  12. Avataaar/Circle Created with python_avatars JOSH2625 says:

    You guys ever notice if you have YouTube open an accidenty touch your phone like YouTube will send you to 15 different ad sites? This site is turning to trash

  13. Avataaar/Circle Created with python_avatars Shodan Cat says:

    Good video! Probably should have added though that an IAC valve can still be the problem even after cleaning because the motors can fail (so don't rule it out if your car/truck is idling weird, you clean the IAC, but it's still doing the same thing.)

  14. Avataaar/Circle Created with python_avatars Hassan Mohamed says:

    Hi Chris, my Mitsubishi Outlander 2007 has a fluctuating rpm only with cold start that it goes between 1300 – 1500 and continue going down as a range for a minute or two then it stops on 650 but very stable idle and drives fine. Could you tell any clues where to start?

  15. Avataaar/Circle Created with python_avatars Bloody Dior says:

    You know what’s even better than Chris fix vids?
    Watching Chris fix videos but owning the exact year stang gt and making 10x easier to find parts lmao 😂

  16. Avataaar/Circle Created with python_avatars RiderX says:

    Hey Chris, I got a question with engine coolant. I saw this ad for Evans WATERLESS system. How would it compare to flushing my 2019 Honda's 50/50 antifreeze to improve engine temps when running it on the track? What are your thoughts and would this be adviseable? (Yep read a bit about it, but I havent seen much application to modern cars such as my 2019 Honda 2.0 Accord; maybe due to costs? but if it keeps the engine temp down and has a lifetime life, why not?) @Chrisfix

  17. Avataaar/Circle Created with python_avatars Robert Evans says:

    Can't remember if it was the oxygen sensor or the mass airflow sensor (I'm leaning towards oxygen sensor) but some years back my old 95 Ford Explorer was lacking power when hitting the accelerator. I found something on line that said to spray the thin sensor wire with brake cleaner. I tried it and the results were immediate and impressive.

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