View Full Version : TB and IAC (idle air control) valve cleaning

04-15-09, 05:36 PM
So this morning, after making a pitstop on the way into work, the car would not stay on—it would stall.

If I applied the gas, no problem... But as soon as I let go the rpms would drop and car would stall.

I checked the carputer for any codes or clues... None. Luckily Ranger was around and pointed me in the right direction = dirty TB plate or IAC.

So here's what happened next.

I cautiously drove back home with one foot on the gas, the other on the brake (not allowing the RPMs to drop below 1000). Pictorial of the surgery, below.

This isn't as good as SL1CKs, but it is for the 2000+ which is quite simpler!

It also shows the IAC valve, which is so easy to take out and clean, but so expensive to replace!


Behold... my clean engine bay. It's more fun to work on a clean engine. I like to keep it clean!

To remove the air intake duct, simply unscrew the two screws on the air filter housing, and


unscrew the slotted bolt holding the intake to the TB.

Here is the IAC plug, two phillips screws hold it in.


When you take it out (After unplugging it) here is the port hole, clean this well too.

Here is the IAC valve, and it's two fastening screws. I cleaned it with electric parts cleaner, so if any of the solvent leaks into the electric motor or windings, it doesn't harm them as it's non-conducive.


This is a dirty IAC valve. The shaft is supposed to be shiny metal, not black soot.

Remove the duct work (unplug MAF sensor plug first)

Dirty TB


Spray it with the TB cleaner. I use a Toothbrush as well.


After the cleaning, the edges are clean and the back of the throttle plate (WOT, shown here) should be clean, as well as the mating area with the TB. Don't worry about the stuff further in, that'll dirty up in no time and does not affect operation.


not everything that shines is gold--this is platinum jk :histeric:

http://i66.photobucket.com/albums/h267/mtflight/dhs/tb%20and%20iac/IMG_0698.jpg The rags will be really dirty.

The heroes of the tale! The electric parts cleaner saved my EGR valve on the Eldorado ETC I owned... u can use regular TB cleaner, but allegedly if you get the electronic windings wet with it, it can become toast! I used the Electric parts cleaner on the $349 retail price IAC.

04-16-09, 01:21 PM
mt, Once again, Well Done !!! This ought to be a sticky for quick reference because NOBODY searches for info..............

WIX filter ????.... :sneaky:

04-17-09, 04:52 PM
mt, Once again, Well Done !!! This ought to be a sticky for quick reference because NOBODY searches for info..............

WIX filter ????.... :sneaky:

Thanks to a friend's advice on the forum, yup. Wix filter!

09-28-09, 04:10 PM
Your instructions are just what I have been looking for. Can you repost the pictures?

09-30-09, 03:01 PM
the pics are live, try refreshing?

10-02-09, 10:12 AM
With exceptions for the surge tank and airbox configurations this is good for the whole 2000+ Seville/Deville series. Nice work.

00 Deville
10-26-09, 11:03 AM
Great tutorial... I would add one warning to the handling of the IAC valve. Don't attempt to move the plunger in and out... it can damage the threads on the worm drive.

11-29-09, 06:01 PM
extremely helpful. i will be doing this very soon. sticky maybe???? :thumbsup:

12-13-10, 05:24 PM
i would also recommend that you take the coolant hose off and out of the way before you unscrew the screws in the ICV if useing hand tools

12-31-10, 03:38 PM
My 2000 DTS was having the exact same problem this week and I thought it was my battery so I took it to get it checked and it was fine...then I thought maybe the alternator or starter...nope??? I stumbled across your post and did exactly as you posted and it starts up fine now...thanks :-)

03-05-11, 03:02 PM
I just took mine out to clean it but I had to be careful because the black part would have shot out due to the inner spring. Does this mean mine is broken and has will come apart? I could easily take mine apart. The plunger slides in and out VERY easily. I cleaned it and put it back together and started it up and now my 2002 Deville is idling at 1300+ RPMs.:cookoo:

Please help. I started this because i was getting a P0507 code.

03-07-11, 05:57 PM
I just took mine out to clean it but I had to be careful because the black part would have shot out due to the inner spring. Does this mean mine is broken and has will come apart? I could easily take mine apart. The plunger slides in and out VERY easily. I cleaned it and put it back together and started it up and now my 2002 Deville is idling at 1300+ RPMs.:cookoo:
Yikes... yeah the IAC I didn't touch. It went bad anyway, about a year ago (much after writing this tutorial).

This is the one I had to buy... it's expensive but this was the best price I found on a new part: ACDelco 214-1098 Idle Air Control Valve Kit http://www.amazon.com/ACDelco-214-1098-Idle-Control-Valve

In the meantime, if the iAC is cycling, you can unplug it when the RPMs are at Idle range with the AC on. I kept it that way for a few weeks while the new part arrived.

04-08-11, 01:12 AM
i have a 2000 cadillac sls and i didnt understand what u meant by unplugging the MAF sensor and when u took the IACV out what did you use for cleaning the port hole?

04-09-11, 10:18 PM
Use TB cleaner. I still have Gumout carb cleaner and use it, though "technically" I've heard it said not to. I've had no problems and see no reason not to.

Most of the time all you need to clean is the TB. If you still have an idle low or high problem, then clean the IAC valve.

Look at picture #1. See the plug on top of the intake duct between the two strap clamps? That's the MAF sensor plug. You have to unplug it in order to remove the intake ducting.

04-10-11, 09:52 AM
i have a 2000 cadillac sls and i didnt understand what u meant by unplugging the MAF sensor and when u took the IACV out what did you use for cleaning the port hole?

Here's your 2000 - 2004 intake ducting setup - the MAF sensor is over next to the air filter adapter - has a plug in top - 5 wires. Don't break a wire - the connector has a safety lock........

Use hobby pipe cleaners - fuzzy wires - to clean out the IAC valve bore in the TB.

You might consider removing the intake duct resonator and closing the hole with a suitable plug which can be clamped: ANY air leak in that intake duct and you get all sorts of mixture problems and a poor idle. Use a suitable Philips screw in the air filter/PCM box cover.

06-15-11, 08:26 AM
So two days ago, I driving on the highway around 60 mph. I needed to get around the vehicle in front of me so that I wouldn't miss my exit, so I had to punch it up to to around 75'ish to go around. After that, I smelled something burning (for only a couple of seconds). After getting off the highway exit, I noticed that my car was idling kind of high.

The next morning, on the way to work, I noticed it again. I had to mash on the break at stop lights because my car was idling around +1000 rpms.

I did some research (internet), and found this thread and forum. (I drive a 2003 cadillac deville BTW)

I pulled the air filter housing, removed the IAC valve, and cleaned the throttle body.

Started her up, and now she's down to 700 rpms. Purrs like a kitten. Thanks for all the help guys, much appreciated.

Now all I have to do is work on the gas gauge.

09-01-11, 03:01 PM
Fantastic! Now I'm ready to roll.

09-01-11, 09:16 PM
I just finished cleaning my throttle body for the first time. I also replaced the air filter. It definitely runs a little smoother and the gas pedal doesn't "stick" after you let off it and then reapply it. Not sure if it's in my head, but I believe there is a little more power too.

After reading many threads about throttle body cleaning, I remember seeing this picture...

http://i66.photobucket.com/albums/h2...c/IMG_0690.jpg (http://i66.photobucket.com/albums/h267/mtflight/dhs/tb%20and%20iac/IMG_0690.jpg)

On my car, I saw where it comes from, however, do I have to unscrew it and clean this also?

Thanks to mtflight for the directions and pictures on how to do this.

09-02-11, 10:40 PM
Usually there is no need to clean the IAC pintle valve if you did a good job on the TB.

11-03-11, 09:02 PM
Thank you for posting this tutorial. I am actually going threw this process right now. I just thought of a few questions while doing this. What if my after market car alarm goes off in the process. Can I start my car with the iac out? And. My throttle body door isn't open. Should I manually open it from the side to clean it better. And last. Should I clean all the way down by and on the springs of my IAC thing?

11-04-11, 05:04 PM
I want to thank you for making this tutorial. It helped me out a good bit. But I have some questions and things to add of my own. My engine was idling very low. Shaking hard at 650. And then I cleaned the tb and IAC and it was idling smooth at a nice 700. But here's my input.

I do strongly.recommend the use of pipe cleaners. The electronics cleaner solution melts plastic. If only I had a picture of my mess lol.

And now my questions

I saw you had the tb in the open position.
Mine wasn't. Do I open it manually from the side to clean the inside.

When cleaning my IAC. Do I clean the spring as well and anything I can get to without manipulating the controller.

Which solution did you use to clean the inside IAC port? Electric or tb cleaner?

11-07-11, 11:38 AM
Hey thanks for the compliment. Pipe cleaners sound like a good idea. The electronics parts cleaner isn't supposed to damage plastics, that's the only reason I suggested it. Using TB or Carb cleaner on the IAC could spell disaster.

I just cleaned the TB on my Eldo (I no longer have the DHS), and I was trying to figure out how I opened the TB. I know I used the wire and a screwdriver in some creative way. This time I just pulled the plastic lever and held it there with one hand as I cleaned the TB with the other.

You may not need to clean the IAC. but do not use TB cleaner for the IAC. You can use TB cleaner for the port, just not the little pricey thingamadoo. I hope this helps

04-20-12, 08:49 PM
Thank you for this thread. I was just about to buy a torque wrench and test the torque on the intake bolts. Saved me a small hassle. I didn't do the throttle body yet but will tomorrow since we got rain but my '01 Seville STS runs like brand new now. Well it actually took two crankshaft position sensors, a map sensor, an oil switch, the intake plenum, a knock sensor that I decided to replace anyways since I was in the intake; starter cost too much, a piece of pvc for a broken vacuum tube, and cleaning the IAC and now she's just like new.

I don't post often but this thread and others have helped me in great times of need. Thanks to all of you. Sorry if I'm threadjacking. I can post in a new thread if I need too.

06-20-12, 12:28 AM
By far, the best thread I have seen in awhile. Thank you, mtflight for posting. Although it won't help with my car, I will pass this on to others with the car to match this procedure. Btw, will you come and make my engine bay all shiny like the one in the pics? LOL KUDOS!!!

12-14-12, 06:47 PM
Was having the identical problem on my 2003 DeVille. Found this post, cleaned the TB & IAC and what I thought might be an expensive problem has been solved. I thank everyone for this site!!!

02-18-13, 08:33 PM
Thanks for this post, very nice tutorial and engine bay for that matter. Would the procedure be similar for a 94 eldorado ld8? Im assuming it is...

02-21-13, 09:02 PM
Yes, except you will not have an IAC valve. You have an ISC motor so just concentrate on the TB bore and throttle plate.

02-24-13, 10:08 PM
Nice job! I like to keep mine clean. I also recommend removing the tb all the way to clean it, that's the way I always do it, and the gaskets are very cheap. I have seen some pretty bad buildup that I would not want run though my motor.

06-17-13, 02:21 PM
ftzeviar, Your CKP post has nothing to do with Tech Tips on IAC or TB cleaning. It has been moved to its own thread in Northstar Performance: 2003 Deville CKP codes ?

10-03-13, 12:22 PM
Good find.
I'm going to clean IAC asap to see if it helps with my stall issue!

10-03-13, 12:44 PM
Ern, Most of us think you have CKP problems - but if you want to clean the IAC, in your car it's held by 2 Philips or Torx machine screws into the left (front) side of the TB. The screws are easy to drop - careful. Remove the IAC and clean the top hat plunger with a bit of TB spray but be careful not to let much/any run into the solenoid body itself. Also clean out the bore and passage in the TB with a fuzzy pipe cleaner - packs of them from craft stores. Rub a drop of engine oil on the O-ring and replace the IAC.

10-03-13, 05:20 PM
Thanks for the illustration.
....not sure about the butt plug, though.

I figured I'll give it a shot. I understand its likely going to come down to the CKP, but I wont have time for that for a week or two.
But thanks for all your time/help. I'll check the IAC tomorrow just to see if it makes any difference.
If it is CKP for certain, think that would cause poor idle at standstill?

Anyway.....if none of this works I'll just get a couple of them chrome fender louvers and be done with it.

10-03-13, 08:59 PM
My bad CKP sensor never caused an idle problem and I can't recall ever hearing of that. When they go bad they cause a longer than normal crank time and/or a stall at idle or sometimes a stumble or stall at cruise.

11-05-14, 02:46 PM
On my 2000 deville base model the vacuum port in this picture has a plug on it. I see in his picture it goes to something?

11-07-14, 03:40 PM
Of course it does - remove the beauty cover and trace the plastic line - or are you talking about the MAP sensor on top ?

IF your Deville has an AIR system, that port is the vacuum source for the two check valves. One on the right (rear) cam cover, the other near the water pump cover.

(A.I.R. - the blower and hose system that supplies fresh air to the exhaust manifolds for some seconds after cold start in order to quickly light off the cat. The number of gray relays clipped to the passenger side strut tower - 0, 1, 2 - tells you if you do or don't have the emissions system installed.)

01-22-15, 06:23 AM
Hi there, I read first page and cleaned my throttle body and iac best of my ability, only had carb cleaner and tooth brus and shop towels, went to start car after all was cleanecleaned and now it high idles at like 1500 or even 2000 rpms, what happened, I'm not putting it in gear like that, that would deviate my transmission, it has 224000. The only reason I wanted to clean iac was cause it had rough low idle and misfire that occurs only at idle, hit gas and runs on all eight whole time not idling, but that's besides point now. How do I fix this, New/used iac, they have them on ebay for 15 bucks aftermarket? Thoughts and ideas. Need my car and can't drive it like that,
p.s., silly me being cureous sometimes, I pushed and pulled on valve while cleaning it to see if it would move more freely, not knowing what I was getting into, put it in clamped everything back up, over rev, shut down, remove, figure if it sticks out and revs up, we'll I'll just push it in and idle down, put it back in and start, revs higher and more erratic, PLEASE HELP, loved my car till iidle issues started.

01-22-15, 08:34 PM
p.s., silly me being cureous sometimes, I pushed and pulled on valve while cleaning it to see if it would move more freely
That may be your problem. You could try pulling both battery cables and touch them together. If that doesn't help, you might try the idle learn procedure. If all else fails, you may have to replace the IAC valve.

Have you pulled the DTC's?

02-01-15, 06:42 AM
That may be your problem. You could try pulling both battery cables and touch them together. If that doesn't help, you might try the idle learn procedure. If all else fails, you may have to replace the IAC valve.

Have you pulled the DTC's?

All I have is rough idle, with random misfire code, got it scanned, p0303, but car only shows p0300 and I know car wont show specific cylinder, but have replaced iac valve just cause was 15 bucks on ebay. Now it idles bit better, but also cleaned egr valve, inside of throttle body and removed and reinstalled tps, now it idles better but while warming up after 1100rpm high idle it surges till fully warm and idles around 650-700 but sill rough. Put it in gear and of course idle drops to about 550-600 and check engine light starts flashing, idle gets rougher, hit gas and stops misfiring and runs on all eight, can floor it and it goes like it should. So dunfounded, don't know what to do next. how do I relearn idle procedure, and what does touching cables together do? Also with removing and reinstalling tps it didn't go back on exactly how it was, slightly turned a tad. now throttle is touchier and when its warming up and go to hit gas, it wants to take off a bit on its own like it revs up, but once warm it acts normal. Thinking I might need to replace tps, but hat wont fix idle issue. And wouldn't i have to have tps relearn or something.But car hast been right since idle issue started. At least I can drive it now. Any more advice, lol?

02-01-15, 10:04 AM
For that car the

TPS relearn is - turn the key ON (no start) for one minute, turn it OFF for at least 30 seconds.

IAC relearn is - START and idle for 15 seconds, engine OFF for at least 15 seconds. Restart and check idle speed at about 650, in P, N, or D and with A/C ON or OFF - all 650 rpm.

(2002 Seville service manual set, powertrain management, fuel/air and sensor(s))

02-01-15, 11:03 AM
what does touching cables together do?
Think of it sort of like a computer reboot.

06-22-15, 04:56 PM
Didnt drive my car for about 2 days because of low idling issues. So cleaned the TB and the IAC port. (Have cleaned the TB before but not the IAC or port) When I took the IAC out the plugger was wide open. I could see the spring and all. So is my IAC bad?

06-23-15, 09:58 AM
Here's what your 2002 IAC should look like. The black "top hat" pintle is attached to a motor that moves it in and out to control airflow around the throttle blade.

RockAuto - and not cheap. Maybe there are a few decent junkyards in your area - any 2000 - 2003 Northstar engine.

08-17-15, 02:42 PM
the pics are live, try refreshing?

hi, so you didn't use any throttle body cleaner?? just the crc motor cleaner??

how often should i clean these?? mine has the same exact problem right now.

08-17-15, 05:43 PM
Depends on the year of the engine. The pre-2000 TB and passages gets filthy pretty quickly due to the location of the PCV dirty air line - at the manifold vacuum tap right at the throttle blade. 2000 and later stay cleaner longer - the PCV dirty air line goes into the intake manifold at the passenger end. Trace it out.

I last did mine in 2010 - still squeaky clean today.

08-17-15, 08:55 PM
I'd recommend doing it as an annual spring cleaning. Once a year makes it a :15 spray and wipe project.

09-20-15, 01:56 AM
My 2003 DeVille was idling rough on startup and the service engine soon light came on. I cleaned the throttle body and when I decided to remove and clean the IAC, including taking the pintle apart, this is what I found (see pics below). There are 2 cracks on the white "collar". Wonder what affect this would have on the idle?? I know, replace the IAC. Thanks for the thread. It was a big help.

05-08-16, 09:15 AM
This is an awesome thread!!!!

........... see Post #1 for pictures.

05-08-16, 10:55 AM
Good catch - mtflight was good at documenting his work. Thanks.

05-08-16, 07:10 PM
Good catch - mtflight was good at documenting his work. Thanks.

Yea, i came in looking for info on a code p0550, but i dnt think its related to the message i recieved from i/c "SERVICE IDLE CONTROL" i cant find it in my service manual cd so i thought id use the best tool The Cadillac Forum.

Ran into this thread and was jus wowed... this is exactly what i want to find for my particular problem! Unfortunately i got interupted and couldnt finish researching my issue to see if theyre infact related

Anyways, great thread, this should def be a sticky post of some sort!!!

04-28-17, 07:59 AM
Ines, Your question on cleaning an escalade throttlebody and idle speed system has been moved from this Tech Tips forum up to the early Escalade forums.

Welcome to CF! Hope all is well in Spain - I made many submarine patrols from Rota during the 60s and 70s. Beautiful country, wonderful Domecq.