I figured this went here rather than External Engine... I'm battling an idle issue with my 383 LS6 with a mild cam. I will be relearning the IAC valve for my throttle body swap soon, but in the process of researching, I found two part numbers for Idle Air Control valves, one for 98-99 and 00-02. Most people speculated there was just a part number change, like GM decided one day, "hey, I'm sick of 17113391 for LS1 IAC valves, let's change it to 17113598!"

Well, I went to AC Delco's site today and searched for both. Indeed, they still have both part numbers! Furthermore, I pulled up the pictures of each and they were just barely different!

17113391 (98-99):


17113598 (00-02):


So, can anyone definitively explain the difference? If they're both still available, wouldn't that generally mean there's a difference so one can't supersede the other?

 

I don't know if they're different but I recently bought the 00-02 one and it works fine on my car, a 2000. Why not just get the one that matches your year and not worry about it? Just curious.

 

Well, that's kind of assuming the difference is electrical, not mechanical. I was moving along that train of thought, but kind of wanted to bounce it off you guys.

Basically, if the IAC valves are physically the same between years, then the bore of the throttle body IAC port is likely exactly the same. This would be supported the fact that people buy 98-02 throttle bodies for 98-02 F-bodies, not 98-99 vs 00-02, thus the IAC valves are not mechanically different between the two versions.

However, that means there is an electrical difference. If there is an electrical difference, what is it? Would it matter if I put a 98-99 IAC valve in a 2000-02 PCM controlled car? Would this make the IAC react differently than it should, thus contributing to idle issues?

 

I tried to find this answer and i never found one. I used up using an iac off a 96 blazer on a 98 TB with a different P/N then what gm said but i also am running a 99+ pcm no issues with the ecu controlling the iac either.

 

I'm going to try to revive this thread since the OP posted some nice pics and info and this question never seemed to be resolved. I just attempted to install my '98 IAC onto my Fast 92mm throttle body and it did not fit at all. I think it technically would've seated into the bore if I would've used the screws to pull it down, but that would've been worthless since I know the o ring wouldn't have survived that. I know it's not me since I had no issues reinstalling the IAC on my old throttle body.

Can anyone confirm that the newer style is actually sized slightly differently? I want to make sure I order the right part since I know what I have isn't going to work.

 

I have a 98 version installed on a Nick Williams 92mm TB. Sealed just fine. Idles like a purring lumpy kitten heh. So differences b/w 98-02 might not be all that bad...

 

I hope its not my FAST throttle body. The IAC is so tight that it unseats the o-ring. Theres no way it will work.

 

I can pull it in the morning to check on the seal. My 98 stuff moved over the the Nick Williams's TB fine from what I can tell. Didn't seem to be an issue.

 

Well the new IAC came in with the 99+ part number. The dimensions look to be exactly the same as the 98 IAC. With that being said, I finally decided to check the dimensions of the bore in the throttle bodies for the IAC. There is virtually no clearance for the IAC in the FAST throttle body (2 thou). Called FAST and they agreed that it was likely a manufacturing flaw in the throttle body. The good news is they are standing by their product and sending me out a new one. The bad news is that I have to pay to ship the old throttle body back before they send out the new one...

So this seems to at least answer the question of the difference between the IACs.

 

V8SC87,

The 1999 IAC you got was the same no doubt as the 1998 you previously had because they have the same part number 17113391.

2000-2002 have part number 17113598 as in the first post.

Anyone find out if there is a difference tuning wise?

 

its not a defect my 92 fast was the same way. i put the oring in the bore first then out in the iac

 

Well I sent the throttle body in. FAST did say they didn't see any issues with the throttle body, but when they sent the throttle body back they sent me an IAC that they supply with their new throttle bodies. It dropped right in just like the IAC did in my original throttle body, so something had to be different. In the end I didn't care because I had a usable throttle body.

 

reviving an old thread but i ran into a problem today... i bought an aftermarket tb and the manufacturer states that there might need to be a modification made to the bore of the iac in case i had the "bigger" iac. there is a difference of almost 25 thousanths between the new tb bore and my old tb. i went to autozone to measure both p.n. but they only had the 00-02 in stock. i'll try to advance tomorrow morning.

 

Can anyone answer the question about the differences between these IACs? Can the PCM control either one? What's the difference?

 

Hey guys,anyone have picture['s of were the I.A.C.valve go's?, i looked and looked,looked,looked,and looked again,but can't find it.SOMEBODY PLEASE HELP.

 

Going by your name if you're looking for one on a Vette they don't have them. They are only used on cable throttle bodies.

 

1998,99,00 have ls1 intake

00 and 02 have ls6 intake
Not sure if that helps you or not but figured id try

 

I'm sure in the past 5 years it got figured out....

 

Only '01-02 came stock with the LS6 intake, so this would not explain the part number break point being for '98-'99 vs. 2000-'02. Either way, the intake manifold would have no bearing on this as the IAC is physically attached to the throttle body and controlled by the PCM (thus the intake has no direct impact).

FWIW, I've used these IACs interchangeably between the various years. No difference in fitment or performance in my experience.

 

I did just recall that the throttle body cam is a bit "faster" on the early throttle bodies, but that shouldn't really necessitate a different IAC. Again, FWIW, I've swapped these around on all different years of (stock) throttle bodies while diagnosing various issues and never seen a performance/behavior difference.

Something obviously caused GM to issue a different part number to run concurrently with the older number, but it doesn't seem to result in any real world difference when used interchangeably.