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Seating for 12
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How-To: Clean the IAC

Does your 3.9L, 5.2L or 5.9L magnum engine rev up and down during idle while in park or netural? If so, the problem is a dirty IAC. Here's the process to clean this IAC to keep your engine happy with a nice idle rpm and avoids wasting fuel too.

A sample look of a 3.9L, 5.2L or 5.9L magnum engine with the van's dog-house removed.



Here's the jewel of the IAC. Notice the driver on the left mounting screw.



Just remove the connector out of the way. ;)



Rats. :VHOT: The fuel bridge is in the way to get the second screw off.



OK, I'll use a longer driver socket and a pair of pliers to get the screw loose.



Now, with the flex drive over the bridge, the screw turns quickly. You may use what ever tools you have to get at that screw too.



*** NOTE ***
NEVER move the IAC brass probe more than 1/4" in travel while cleaning or handling. !!?!! Right now the picture shows it all black.

Ah, here's what the IAC looks like. OK, think clean thoughts here.



Up close all dirty ...



My cleaning bench. :)



A cotton swab and clean rag.



The IAC cleaned up really good.



Ah, but wait, there is more!!! The TB port is dirty too!





One clean IAC port. That's how it's too look. OK, clean thoughts here too.



Alright, just put the IAC back into the hole, drive the screws and plug in the connector!

Hope this helps too!
 

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Seating for 12
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Discussion Starter #3
Thanks Ram Man!

I made sure the pictures we small enough in file size so the 56k dial-up people can see this thread too. (I'm on dial-up as well.) ;)
 

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vanner
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Thanks for the info, I may clean mine someday, I have 109k miles on it now, I guess its probably due.
 

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Do It In A Van
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Mine's still idling great at 133,000 miles. I'll clean it eventually.

That's a great tip Stev.
 

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Seating for 12
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Discussion Starter #6
For us Ram Van owners, it's really an easy job to do. For the Ram Trucks, that's another story, but not impossible.
 

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Seating for 12
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Good news to report, the DW rode in the van today. She commented how the engine noise seemed to have disappeared! So, all of that engine rev'ing has stopped too!
 

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what if ???

What heppens if you do move the probe more than 1/4'" ?? I juat wanna know so if i accidentally do i what what i would have to do to remedy it !

One more question how would i go about cleaning entire throtle body assy? and what to be carefull with in that job
sorry about spelling its been long day
 

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If you move it more than 1/4 " you will ruin it as it is not meant to travel that far.
It sucks when you make that mistake. I have done that on my Buick and had to buy a new AIS for it.
 

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I did the same thing when I replaced throttle body to a fastman unit and I replace the throttle possition sensor (surging in cruise control). On V10s, it is easier to remove the whole throttle body and clean the whole thing cause the back air bank p/u oil residue from the vent hose from the valve cover vent hose.
 

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Wow!! I think you have just help me solve my problem. Can't wait to clean mine. My Haynes repair manual is useless compared to your pictures. I've been looking for hours trying to find this valve. I have different TBI but at least I have a clue to were it's located and how it works. Thanks
 

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Wow!! I think you have just help me solve my problem. Can't wait to clean mine. My Haynes repair manual is useless compared to your pictures. I've been looking for hours trying to find this valve. I have different TBI but at least I have a clue to were it's located and how it works. Thanks
 

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Seating for 12
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Discussion Starter #13
DD,

I'm glad this helped out. This is an all to common thing that people are searching for to clean, inspect or repair. Yes, the Hayes Repair Manual #30065 is a little bleak at best for pictures or the real location of this part. The manual has good information about the proper care and warning not to push on the plunger, but it lacks for the images.

Stev
 

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Stev, Do all TBI's have a IAC valve??? I have a 1990 Power Ram, 318, (5.2?) with a Holley TBI. It doesn't want to stay running in cold weather. I'm the person with the Hayne's manual and its seem to state it's in the intake manifold? The illustration in the book looks like they may be working on the throttle body but it is very unclear where. (Front, back or side?) Parts store says "we don't show a IAC valve on that year truck in our parts book." Do you know if Dodge installed more than one model TBI in 1990 trucks. I haven't been able to locate any numbers for reference on the TBI. I will try to call Holley in the morning to see if they can tell me where to obtain a blow-up of this TBI for parts. Another question-- is there such a thing as a vacuum assisted IAC valve? Again I was very impressed with your write-up about cleaning the IAC. (AND ESPECIALLY THE PHOTOGRAPHY!!!) I curse the Haynes photographer. Thanks again, DD
 

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Seating for 12
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Discussion Starter #15
DD,

As stated in the original posting, this IAC cleaning is for the Magnum engines. I have no working knowledge of the pre-magnum series engines except for the /6 198's & 225's.

Ok, that gives away my age. ;)

Stev
 

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Seating for 12
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Discussion Starter #16
ANOTHER FYI ---

Just before the IAC port hole in the TB, you will find a thin slotted hole below it. VERY carefully, use an ear swab soaked in carb/injector cleaner and wipe this slot out inside. Just make sure you don't press tooooo hard and break the ear swap end off in the TB.

I have a photo of this setp too when I get time to find it and post.

Stev
 

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Testing the IAC

2000 RamVan B1500 5.2L
I have a question for you Steve. I cleaned my IAC per your instructions. It had very minor carbon on it, most of the brass was not discolored at all. I reinstalled it, but I am still getting the P0505 code. I had read in another forum that you could test the IAC by doing this:

1. Remove the IAC and with the connector still attached
2. Turn the key to 'ON'. This should cause the pintle to retract.
3. Then turn the key to 'OFF'. This should allow the pintle to extend back out.

Do you know if this would work?

Thanks and Take Care, Sharon
 

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Seating for 12
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Discussion Starter #18
Sharon,

Per my Hayes Repair Manual #30065, by no means allow the IAC pintle to travel more than 1/4 inch while outside of the TB housing. Going over the 1/4 inch of travel will damage the IAC internally.

OK, I have recently done this on the 2001 B2500 5.2L due to some other Pxxxx codes.
http://www.dodgetalk.com/forums/showthread.php?t=138174

What amazed me the most was the IAC pintle and how it retracted. It sounded like an old wooden chair creaking as it drew back slowly while slightly chocking off the air coming in. I repeated the step a few times more prior to totally stalling the engine on the last go around. Do you see the hole that the pintle mates to in the TB? Between that hole and the two valves there is a space. That's where you put your finger to cover the hole. Don't put your finger into the hole because the pintle can pinch it. ;)

While I was working on the TB and the TPS and IAC to fix the limp home issue, I had tried vairous things of unplugging the IAC connector and running the engine too. Of course it threw the P0505 code as well.

Just review the link I gave in this posting. ;)

Peace!

Stev

PS, it's good that you have found this Dodge forum as well. There are many people here and it's very active.
 

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I am going to try your trick for checking it, but honestly, I just don't think anything is wrong with it. I bought a new one to put on, but when I went to pull the old one, it looked great. The van has 50,000 miles, doesn't act up at all, and goes down the road nicely. Unless the change has been slow and I haven't noticed any difference. Yes, my gas mileage is low, but it is a van, and a 5.2, so I expect that. I am just trying to do whatever it takes to get that pesky engine light off! :dunno:

Thanks and take care, Sharon
 

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Seating for 12
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Discussion Starter #20
Try some CRC QD eletronic cleaner on those contacts as well. A few part stores carry that. I know NAPA in our area does.
 
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