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-   -   High idle (https://www.turbododge.com/forums/f4/f15/975866-high-idle.html)

spearscrue 08-05-2015 06:55 PM

High idle
Looking to see if anybody has ran into this problem, I replaced my 46mm stock throttle body on my 87 Shelby CSX with a 52mm throttle body and now my car idles around 2500 rpm. My car ran perfect prior to this swap. I thoroughly cleaned the used T.B. I purchased, reused the T.P.S. Sensor and A.I.S. Motor from my oem T.B. Installed a new gasket and now it will not idle down below 2500 rpm even with the idle set screw backed all the way out, I also read NAS sticky on how to reset the A.I.S. Motor and nothing has changed, I rechecked ALL my NEW vacuum lines installed last year and found no problems. Anyone have an idea on what could be causing this?

NAJ 08-05-2015 08:05 PM

Re: High idle
One of three things happened.
1)You increased airflow enough that the Controller/AIS cannot bring the idle speed down.
2)The AIS used in the 52mm TB is different than the AIS used in the 46mm TB.
3)The throttle plate is stuck open either due to a warped plate or the throttle cable is holding it opened.

spearscrue 08-05-2015 08:43 PM

Re: High idle
I consulted with Boost Button (he has been doing my programming for awhile now) prior to doing this swap and he said I would most likely not have to change any programming. I was told the A.I.S. motors were the same, the throttle cable is definitely long enough, I have not checked for a warped throttle blade yet, I think I would of caught it when I cleaned it. Hopefully I get it figured out soon the Woodward dream cruise is on the 15th. Lol!!

NAJ 08-05-2015 08:56 PM

Re: High idle
Other than what I posted the only other things that would cause a high idle are...
1)AIS is not moving
2)Large Vacuum Leak.

spearscrue 08-05-2015 09:03 PM

Re: High idle
I called Autozone and O'Reillys and had them both check the part number for the AIS motors for my OEM T.B. and a 1987 caravan with a 3.0 which is what I am assuming this 52mm T.B. Came off of and yes both Autozone and O'Reillys said they are different part numbers. Hopefully that is the problem.

moparracer 35 08-05-2015 10:10 PM

Re: High idle
The AIS motors have different sized tips and the smaller one won't cover the hole in the larger throttle body so it doesn't shut it down to idle. Sometimes they will unscrew completely and come apart.

spearscrue 08-05-2015 11:42 PM

Re: High idle
That certainly makes sense, I will look at that when I go to check out a new ais for a 3.0 tomorrow.

cheezit53 08-06-2015 05:15 AM

Re: High idle
The pintle is different for each TB, use the one that came with the 52mm.

spearscrue 08-06-2015 09:53 AM

Re: High idle
The T.B. I bought didn't come with a tps or ais, pretty much stripped down. I'm going to Autozone today to buy the correct one. Another $60 Oh Well!! I am pretty confident this will fix my problem. Thanks Everyone for your help!!!

Moparkid2.2 08-16-2019 08:21 AM

Re: High idle
i know its 4 years later, but did that fix the problem?? thanks

spearscrue 08-16-2019 11:38 AM

Re: High idle
I had to go back to the original Throttle Body and that fixed it. I found out later that if you plan on going with the larger T.B. you have to do some port work to the intake which I wasn't willing to do.

Sent from my GM1917 using Tapatalk

tryingbe 08-16-2019 02:07 PM

Re: High idle

Originally Posted by Moparkid2.2 (Post 4512919)
i know its 4 years later, but did that fix the problem?? thanks

2 piece intake manifold? If so, you left of the bolt under the elbow of the intake manifold.

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