Cleaning The Iac Valve And A Basic Engine Cleanup

[jdnet]

Ok guys This is a how-to on a basic clean-up that covers one part thats overlooked most of the time. This is the IAC valve. For info on the IAC valve just go here. http://www.2carpros.com/articles/how-idle-air-control-valve-works

Anyway this write up is for a 3.0 v6 tribute but the process is similar on most vehicles.

Here's what you need

Clean dry rags

Carburetor cleaner (you can easily find it at the auto section in arpico. There are a few brands o choose from and cost between 450-600 a can).

Basic socket set with a ratchet. (I used a torque wrenchto tighten the bolts to spec but a ratchet wouldbe fine).

A slight engine clean up.

With the engine running and the air filter out spray some carb cleaner into the air intake. Use 1-2 second bursts. You engine will act like its about to stall, when that happens just stop for a couple of seconds till it gets back to normal. While going this have someone rev the engine between 4-5000 rpm. You should see smoke comming out of your tail pipe. I would not breathe in the smoke if I were you. After revving it for 1-2 mins you are good to go. This ends the carb cleaning part of the tuneup.

Cleaning the IAC valve.

With the engine cooled down locate your IAC valve and unplug the wiring harness on the back of it.

Proceed to remove it and inspect it for build up. You should see a lot of carbon buildup if it has never been cleaned.

Take your carb cleaner and spray the inside of the valve. The carb cleaner can should come with a small straw that goes into the nozzle. Use this to spray the inside of the valve and break up the carbon deposits.

Spray carb cleaner for a second time and shake the IAC valve dry. Also make sure you spray carb cleaner and cleaned the contact points.

Next, look at the area on that the valve was mounted to. You should see build up down the two holes. Spray carb cleaner and clean it.

The next step is something I skipped but needs to be done. Ran out of gasket maker today so it will have to wait till tomorow.

Remove the old gasket where you set the valve using a flat head screw driver. Always be gentle as the metal on these parts as the metal is soft in comparisomn to other areas. Use the gasket maker to created a new gasket in the recessed area where the old one was. Once the gasket sets (refer to packing for those details) place the valve back and put the bolts back in. Always hand tighten bolts as much as you can and then use the ratchet. This will help prevent stripped threads. If you have a torque wrench then use

the manufacturers specs if not tighten it softly and make a 1/2 to 1/4 turn.

Plug the harness back in, start the car up and let it idle. If you valve had a lot of build up you would notice a much smoother idle. Either way cleaning it up is good as it will extend the life of the valve.

If you have any questions please do ask. If I can;t answer them some one else should be able to. Also if you like these posts and find them helpful please let me know. It will help me know that i'm not wasting time writing these up. I was going to clean the EGR valve too but ran out of time today. I will update this post whenever I get to it.

If you don't see detailed pictures on this post it means I haven't loaded them as yet. PLease check back. I'm having some issues with photobucket today.

Edited December 5, 2010 by jdnet

[jdnet]

Forgot to note that You should allow the sensor to dry before installing. If there is a wierd whine comming out of your engine bay it's that it wasn't completely dry. This should go away after a day or two. Also let the engine idle for a few mins and warm up.

[heavyD]

You really like getting you hands dirty eh? Good write up man, I feel like going and buying myself a toolkit now...

Naaaaaah, on second thoughts I won't, I'll probably blow my engine trying to do something stupid.

Edited December 5, 2010 by Big_D

[jdnet]

You really like getting you hands dirty eh? Good write up man, I feel like going and buying myself a toolkit now...

Naaaaaah, on second thoughts I won't, I'll probably blow my engine trying to do something stupid.

Lol I'm just enjoying my last days of freedom until my wife moves over here. FYI stuff like removing IAC valves and cleaning is much easier than it looks. The whole process of removing and cleaning the IAC valve would have taken me only 10-15 mins has I not been taking pictures. Just take the leap and get some tools. Lol. It's an addiction.

[Sifaan]

Hi jdnet

In case of an EFI engine, I presume the first part is skipped completely? And then is carb cleaner still the best product for cleaning the IAC valve?

Is there any indication of how often this should be done (kms / months)? or just whenever the engine idle is rough?

and last but not least, how would we identify the IAC in the first place ?

BTW I find your DIY posts useful in general, although my wife'll probably kill me if I try anything on the engine :S

[jdnet]

Hi jdnet

In case of an EFI engine, I presume the first part is skipped completely? And then is carb cleaner still the best product for cleaning the IAC valve?

Is there any indication of how often this should be done (kms / months)? or just whenever the engine idle is rough?

and last but not least, how would we identify the IAC in the first place ?

BTW I find your DIY posts useful in general, although my wife'll probably kill me if I try anything on the engine :S

Well the tribute does has an efi engine as far as I know. Spraying the carb cleaner does help clear out deposits through out the air intake piping all the way down. As for if carb cleaner is the best product for cleaning IAC valves, as far as I know it is. It helps remove the carbon deposits effectively without the need to agitate them. Although if the deposits are tought you may havetouse a cotton bud.

To find the IAC valve, simply locate your trottle housing. It will be bolted onto it and have a wiring harness connected to it.

As for the question on how often the IAC valve should be cleaned, I can't exactly say but looking at how badly mine was and taking into account the miles I have I would say about every 45,000. Just a rough estimate.

Last but not least.....as for your wife attempting to murder you if you worked on the engine, I will not be held liable for deaths caused by spouses. Please direct questions such as that to my attorney. .

[Elvis_Pil]

Good article machan Used to do the same thing on and off on my old civic. What I've found is that you can't use these methods on newer cars- especially those with drive by wire systems. The moment a sensor is out- you simply cant fire the engine up. Sadly- the days where you could do a lot of DIY stuff on motors are numbered..

[360_Cruiser]

Excellent write up This is a simple yet gr8 DIY. I did this on my Accord sometime back and it made the car run/idle smooth. It also took care of an erratic idling problem that the car use to have on cold starts.

[The Don]

An excellent write up as always JD.

Perhaps an interesting point to add is that ICVs come in different designs. On Mitsubishi's its got a plastic pole which extends forward and back and when they fail they seem to get stuck in the extended position.

But the cleaning method is exactly the same as you suggest and sometimes you can fix a stuck ICV valve that way.

Also at least in Mitsubishi's a good way to figure out if the ICV has failed is to start the engine and while the engine is running remove the unplug the wiring connector from the ICV. If it's working properly your engine should start to stall. If it's failed your idle speed will go up immediately.

[upulhad]

Much help full one Thanks for share...

[charitha19]

another good one,.,

[terrabytetango]

I'm going to attempt this during the weekend. It will be the first time I'll be properly getting intimate with an EFI engine. I've got a check list of things to do and this seems to be a nice place to start taking things apart from.

[Rumesh88]

recently my suzuki swift ran out of fuel and engine stopped. i managed to pump some petrol in the next few minutes and resumed the ride. now i i feel the idle speed has dropped and also when i got at a good speed 50 - 60kmph the engine slows down very fast than it was before. went to my mechanic who said everything is normal and his computer also did not indicate any failures also he cleaned the injector just to keep me happy (although he is my fried) but as the driver i feel the difference. what could be the issue? can someone help me.

Get your fuel filter checked. Better still if you can get your fuel pressure checked for if the pressure is down it can be the filter or the pump. Once the fuel level goes down the pump draws from the tank bottom and there is a good chance for the debris to clog the filter or get into the rest of the system.

[aakyl4ever]

Very helpful article. I need to do this for my civic.

[Davy]

Hey guys, sorry for asking a question on a DIY thread, but there are so many threads on the subject and this looked like the best one to ask this.

So I took apart the throttle body during the weekend and gave it a thorough cleanup. I basically took the entire throttle body out of the car, cleaned out the old gasket and took off the Throttle Position Sensor and the Idle Control Valve. Used a lot of carb cleaner on the throttle body and the ICV and cleaned the unit up and installed it. During the process, I had the battery disconnected.

After installing the throttle body back in, I ensured that the vacuum lines, water lines (there are two water lines coming to the ICV chamber) and connectors are properly secured. Started her up and she was idling perfectly at 800 RPM. I took the car for a spin to make sure that everything was working fine and gave it some high revs (4000 - 5000 RPM or so) as well during the test run.

After about 5 minutes of driving, the car bogged down and died with a really low idle (500 RPM). I switched off the AC and then the car manages to stay at 800 RPM, but as soon as the AC comes on, the RPM drops really low and dies. Happened a couple of times and I went back home, removed the ICV valve anc cleaned it again and put it back in. It was perfect again after that. The engine idle RPM was 800 and the ICV managed to sort things out even when the AC kicks in.

On the next day, I started the car up and she started up fine but the RPM went all the way up to like 1500 and stayed there (even when the engine is warm). When I switched on the AC, the RPM came down to 800. I couldn't attend to the issue on that particular day cause I was busy all day and just started the car up again and tested at night and the RPM was again at 800 without AC and stalled when the AC came on - with a bit of struggle and vibrating on about 500RPM. Looked around for loose connections and vacuume lines, but I couldn't find any.

Looking for some inputs from you guys before I remove the throttle body again. What should I be looking for here? Blocked vacuum line?

Other pointers that might be helpful:

- I had a spare throttle position sensor at home (which was working) and I installed it after the cleanup and removed the one that was already on the car. No reason, the TPS that was on the car was a recon one while the one at home (now mounted) is the genuine one that came with the car. The recon TPS was working fine too.

- The RPM sometimes fluctuates randomly between 800 and 1500. Sometimes goes up/down when I switch on headlights as well.

- I noticed that the intake manifold is covered in carbon on the inside.

- Injectors underwent an ultrasonic cleanup about a week ago (hence why I decided to clean the throttle body).

- On the test run, when the car stalled, the Check engine light came on and disappered when the car was started again. Never came back on again after I cleaned the ICV for the second time.

- The chamber onto which the ICV mounts is held on to the TB with four screws and can be taken off. It is to this chamber that the IN and OUT water lines are connected. The mounting screws were so damn tight I couldn't remove this part, so I sprayed carb cleaner through the hole onto which the ICV was mounted.

Thanks in advance.

[Rumesh88]

Did you try a TPS reset by momentarily disconnecting the TPS and reconnecting (easily said than done of course) while engine is warm and in idle?

[Davy]

Did you try a TPS reset by momentarily disconnecting the TPS and reconnecting (easily said than done of course) while engine is warm and in idle?

I did not try that Rumesh. Sorry for my ignorance but is that a safe way of resetting the TPS? Also, I assumed that the ECU would have anyway been reset because I did all the above work with the battery disconnected.

The TPS socket can easily be removed as it's in a place where it can be easily accessed. So I guess it should not be a big issue. If the problem persists, I might try switching back to the TPS that was on the car before the cleanup.

Edited March 31, 2014 by Davy

[The Don]

Hey guys, sorry for asking a question on a DIY thread, but there are so many threads on the subject and this looked like the best one to ask this.

So I took apart the throttle body during the weekend and gave it a thorough cleanup. I basically took the entire throttle body out of the car, cleaned out the old gasket and took off the Throttle Position Sensor and the Idle Control Valve. Used a lot of carb cleaner on the throttle body and the ICV and cleaned the unit up and installed it. During the process, I had the battery disconnected.

After installing the throttle body back in, I ensured that the vacuum lines, water lines (there are two water lines coming to the ICV chamber) and connectors are properly secured. Started her up and she was idling perfectly at 800 RPM. I took the car for a spin to make sure that everything was working fine and gave it some high revs (4000 - 5000 RPM or so) as well during the test run.

After about 5 minutes of driving, the car bogged down and died with a really low idle (500 RPM). I switched off the AC and then the car manages to stay at 800 RPM, but as soon as the AC comes on, the RPM drops really low and dies. Happened a couple of times and I went back home, removed the ICV valve anc cleaned it again and put it back in. It was perfect again after that. The engine idle RPM was 800 and the ICV managed to sort things out even when the AC kicks in.

On the next day, I started the car up and she started up fine but the RPM went all the way up to like 1500 and stayed there (even when the engine is warm). When I switched on the AC, the RPM came down to 800. I couldn't attend to the issue on that particular day cause I was busy all day and just started the car up again and tested at night and the RPM was again at 800 without AC and stalled when the AC came on - with a bit of struggle and vibrating on about 500RPM. Looked around for loose connections and vacuume lines, but I couldn't find any.

Looking for some inputs from you guys before I remove the throttle body again. What should I be looking for here? Blocked vacuum line?

Other pointers that might be helpful:

- I had a spare throttle position sensor at home (which was working) and I installed it after the cleanup and removed the one that was already on the car. No reason, the TPS that was on the car was a recon one while the one at home (now mounted) is the genuine one that came with the car. The recon TPS was working fine too.

- The RPM sometimes fluctuates randomly between 800 and 1500. Sometimes goes up/down when I switch on headlights as well.

- I noticed that the intake manifold is covered in carbon on the inside.

- Injectors underwent an ultrasonic cleanup about a week ago (hence why I decided to clean the throttle body).

- On the test run, when the car stalled, the Check engine light came on and disappered when the car was started again. Never came back on again after I cleaned the ICV for the second time.

- The chamber onto which the ICV mounts is held on to the TB with four screws and can be taken off. It is to this chamber that the IN and OUT water lines are connected. The mounting screws were so damn tight I couldn't remove this part, so I sprayed carb cleaner through the hole onto which the ICV was mounted.

Thanks in advance.

Davy, sadly I've had the same issue as well. You did one thing wrong, which is you should not use carb cleaner on the ICV, and the jury is out as to if you should use carb cleaner on the chamber on the ICV which control idle up when the engine is cold.

Particularly on Mitsubishi's I've read quite a few articles where the wax like material inside the chamber, which melt as warm water is circulated to slowly bring down the RPM (its an override of the ICV) gets damaged when in contact with carb cleaner.

Personally the only bit I will actually clean is the butterfly valve area of the throttle body, and the ICV with something a bit milder (though I see loads of mechanics carb cleaner on that as well). You are talking to a guy who has 3 ICVs as back up as my car has been plauged with issues on idle speed since the day it was bought. Luckily the idle is stable now, though had a number of issues.

In my car at least the ECU took quite a while to learn to stabilize the RPM after the fixes. The symptoms were the same as yours, when the engine started the RPM will reach around 2500, hold it there and then slowly come down, but not as quickly as it should.

The issue I think is either with the system which controls idle up during a cold start or your ICV. Or your ECU is still learning.

Try cleaning the inside of where you sprayed carb cleaner inside because the residue might be causing the wax not to behave as it did before.

If the RPM does come down to 800 (or whatever stable rpm with AC in your car is) after a few minutes, I will wait and see for a little bit.

[Davy]

Davy, sadly I've had the same issue as well. You did one thing wrong, which is you should not use carb cleaner on the ICV, and the jury is out as to if you should use carb cleaner on the chamber on the ICV which control idle up when the engine is cold.

Particularly on Mitsubishi's I've read quite a few articles where the wax like material inside the chamber, which melt as warm water is circulated to slowly bring down the RPM (its an override of the ICV) gets damaged when in contact with carb cleaner.

Personally the only bit I will actually clean is the butterfly valve area of the throttle body, and the ICV with something a bit milder (though I see loads of mechanics carb cleaner on that as well). You are talking to a guy who has 3 ICVs as back up as my car has been plauged with issues on idle speed since the day it was bought. Luckily the idle is stable now, though had a number of issues.

In my car at least the ECU took quite a while to learn to stabilize the RPM after the fixes. The symptoms were the same as yours, when the engine started the RPM will reach around 2500, hold it there and then slowly come down, but not as quickly as it should.

The issue I think is either with the system which controls idle up during a cold start or your ICV. Or your ECU is still learning.

Try cleaning the inside of where you sprayed carb cleaner inside because the residue might be causing the wax not to behave as it did before.

If the RPM does come down to 800 (or whatever stable rpm with AC in your car is) after a few minutes, I will wait and see for a little bit.

Thanks for the reply The Don. I used carb cleaner on the ICV simply because I have seen many mechanics and garages use carb cleaner on it. Unfortunately, I guess the damage is done now if what you said is correct. As for the wax you have mentioned, is it inside the ICV actuator assembly or the chamber onto which the ICV is mounted on the throttle body? The ICV itself is just a brushless motor as I have found and does not contain any wax.

The clip below on YouTube shows the inside of the ICV but I am reluctant to take this apart as I read in many forums about people who tried to take this apart and broke the brownish plastic part which makes the ICV unusable. The video below makes it look so easy, but I guess the story is different for a ICV which has been working for over a decade.

If you meant that I should clean the ICV chamber on the throttle body, then you might be right. That is the only part in the throttle body that I could not fully get into because of the 4 screws which were really tight. I will give it a try again and get back to you.

The chamber onto which the ICV connects on the TB is as follows:

This is the ICV before being cleaned:

I replaced the throttle position sensor today with the one that was already on the car and did a reset as Rumesh explained. The situation is still the same. :S The car sometimes stalls when it idles without AC. The car is generally underpowered now and a random miss also happens when driving at a moderate speed.

One observation: Before all this, when the ignition is turned on, there was a slight "pssst" sound from the TB area and now it's turned into a "click click click click....... click click". I asked someone to turn the ignition on and tried to inspect where the click was coming from but was unable to locate the source.

Edited March 31, 2014 by Davy

[The Don]

Davy, as far as I know the wax is inside the throttle body, not in the ICV itself. I don't think the ICV gets damaged due to carb cleaner (though some advice against its use on the ICV as well), but its this wax like compound.

To explain (and you will understand it straight away), you would have already noticed the waterline coming into the throttle body and out of it bringing water from the engine. Basically this warms the wax and causes a bypass valve to close. The idea is when the engine is cold, the wax will keep the valve open which bypases the throttle body butterfly and the ICV keeping the idle up to get the engine to warm up quickly. But as it does it slowly closes it, causing the idle to drop to normal.

I think its this mechanism which is messed up. If you check on Google you will find the most common issues are a stuck ICV or this. In my car we literally closed the idle adjuster screw and the idle would still not drop. At that point there could only be two culprits (we even tried two other throttle bodies). It could be the ECU keeping the bypass open by way of ICV or its this mechanism.

Does your idle drop to stable at some point, though it might hold for longer than usual?

[Davy]

The Don,

Understood about the wax on the throttle body. I guess there is no way of knowing if the wax is in place because it obviously is in a sealed chamber. However, I read on another forum specific to the Lancer CS that the water supply is simply to warm up the idle servo mechanism so that the intake air heats up much quicker and to allow the idle RPM to drop to a stable level much faster. Apparently this is intended for cold countries mostly.

I think you're making a valuable point here because when I checked with UniMo about the ICV, they said that it comes with the entire mechanism (the chamber with the water lines with the ICV mounted on to it). Another forum post also confirmed that there is infact a "thermostat" inside the chamber where the water lines are fed into. Unfortunately, this particular part costs Rs. 39,850 at the agents when I called them up yesterday to check. I did a search for the part number, but was unable to find it on eBay. I will do further searching. The ICV can be bought down from eBay from Rs. 7000 (Chinese aftermarket) to Rs. 14,000 (genuine, brand new). I'll do a bit of searching at spare parts shops to find the entire mechanism.

I also read in the workshop manual that placing the throttle body gasket incorrectly is a direct cause of poor idle RPM. I think I will take off the throttle body again and inspect everything one last time to just to make sure that everything is in place. As I mentioned before, I was unable to take off the four screws that unmounts the ICV chamber. I will try again to see if I can get that off as well.

Right now, the car is at home without being used. It's impossible to drive because the engine stalls as soon as I let go of the throttle. It's worse when it's cold and the cold idle is as low as when the car heats up. The idle doesn't stay in one place either, it moves randomly from 500 - 1000 or so. It is when it comes down to 500 or so that the engine cuts off.

Thanks for the input guys. Much appreciated!

[Davy]

Davy, as far as I know the wax is inside the throttle body, not in the ICV itself. I don't think the ICV gets damaged due to carb cleaner (though some advice against its use on the ICV as well), but its this wax like compound.

To explain (and you will understand it straight away), you would have already noticed the waterline coming into the throttle body and out of it bringing water from the engine. Basically this warms the wax and causes a bypass valve to close. The idea is when the engine is cold, the wax will keep the valve open which bypases the throttle body butterfly and the ICV keeping the idle up to get the engine to warm up quickly. But as it does it slowly closes it, causing the idle to drop to normal.

I think its this mechanism which is messed up. If you check on Google you will find the most common issues are a stuck ICV or this. In my car we literally closed the idle adjuster screw and the idle would still not drop. At that point there could only be two culprits (we even tried two other throttle bodies). It could be the ECU keeping the bypass open by way of ICV or its this mechanism.

Does your idle drop to stable at some point, though it might hold for longer than usual?

To answer your question, this is my idle after about 10 minutes of continuous engine operation. Very erratic as you will see. Note that his is without the AC on. It's impossible to keep the engine running with the AC on now.

http://vimeo.com/90721314

Further, I searched and got hold of the engine workshop manual for the fuel system and it has detaild info on how to check the ICV. I have mentioned in one of my posts about a difference in a sound coming from near the throttle body after the ignition is switched on. And that is actually part of the test to verify if the ICV is activated. In my case the operation sound can be heard but its different. So I'm guessing that the activation circuit and ECU are fine but it's something to do with the ICV itself.

Edited April 2, 2014 by Davy

[The Don]

To answer your question, this is my idle after about 10 minutes of continuous engine operation. Very erratic as you will see. Note that his is without the AC on. It's impossible to keep the engine running with the AC on now.

http://vimeo.com/90721314

Further, I searched and got hold of the engine workshop manual for the fuel system and it has detaild info on how to check the ICV. I have mentioned in one of my posts about a difference in a sound coming from near the throttle body after the ignition is switched on. And that is actually part of the test to verify if the ICV is activated. In my case the operation sound can be heard but its different. So I'm guessing that the activation circuit and ECU are fine but it's something to do with the ICV itself.

If the RPM is stable without the AC and if it drops rapidly when the AC is switched on and then tries to stall, with anti stall kicking in, the issue is likely to be a faulty ICV.

An easy way to verify it is to take the wire connector off the ICV while the engine is running and if I remember right if the rpm goes up at that point then its likely the valve is faulty.

The ICV used to be a pariticularly weak component in Mitsubishi's and other brands which used the Mitsubishi part. Sadly I can't see your pics as images are blocked in my office, so I can't verify is its the type that I'm talking about.

[Davy]

If the RPM is stable without the AC and if it drops rapidly when the AC is switched on and then tries to stall, with anti stall kicking in, the issue is likely to be a faulty ICV.

An easy way to verify it is to take the wire connector off the ICV while the engine is running and if I remember right if the rpm goes up at that point then its likely the valve is faulty.

The ICV used to be a pariticularly weak component in Mitsubishi's and other brands which used the Mitsubishi part. Sadly I can't see your pics as images are blocked in my office, so I can't verify is its the type that I'm talking about.

Tried this when the engine is cold (and running) and there is absolutely no change in RPM when the ICV connecter is removed. Drove for about 10 minutes with the ICV disconnected and the engine RPM went higher and higher with time and reached about 1800 without AC.

As for the ICV being a weak component of MItsubishi, I couldn't agree more. I've been driving with a sticky ICV for the last year or so despite it working most of the time. On random occasions, the car's idle would jump to 2000 or so as soon as I start it (even while warm). This is mainly why I wanted to clean the system.

I am on the lookout for a replacement ICV. If I'm lucky, I should be able to get my hands on one today. Will keep you posted. Thanks again for your input. Much appreciated.

[The Don]

Tried this when the engine is cold (and running) and there is absolutely no change in RPM when the ICV connecter is removed. Drove for about 10 minutes with the ICV disconnected and the engine RPM went higher and higher with time and reached about 1800 without AC.

As for the ICV being a weak component of MItsubishi, I couldn't agree more. I've been driving with a sticky ICV for the last year or so despite it working most of the time. On random occasions, the car's idle would jump to 2000 or so as soon as I start it (even while warm). This is mainly why I wanted to clean the system.

I am on the lookout for a replacement ICV. If I'm lucky, I should be able to get my hands on one today. Will keep you posted. Thanks again for your input. Much appreciated.

You know what man, I've had the same symptoms, though this time when I went home I noticed the problem seems to have fixed itself.... sort of.

http://www.lancerregister.com/faq_f22.php

Below is an excellent article on removal and fixing the issue

http://www.4x4wire.com/mitsubishi/tech/throttle_body/

Does sound like the ICV is failed if nothing happens if the connector is removed. I think the behaviour I mentioned implies that the ICV is working.