2.5 to 4.0 throttle body, Idle issues, Again! - Page 2 - JeepForum.com
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Unread 02-22-2013, 05:34 PM   #16
az_zoner
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So I pulled the 2.5 housing and IAC off and here is what it looks like inside. Should the tip of the IAC be that far away from the hole? (don't go pervert on me here). I looked at the 4.0 set up and it is in contact and seals the hole.

I also went to Auto zone and looked at one of their IAC and it is even further away. Or could it be that these things stop in any location when turned off and drive to a set point when started.

I think I'm starting to understand how it works, just wondering if the PO's of the parts I have bought may have swapped a few things around. Is there any quick way to test the IAC to see if it drives in and out?

cb

iac-rs.jpg  
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Unread 02-22-2013, 06:44 PM   #17
pete1991YJ
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Plug it in, start the jeep, and see if it moves in and out when you goose the throttle. IMHO that tip looks like its WAY too far away... maybe you can try different IAC's? I thought you had to use the same IAC that came with the throttle body?
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Unread 02-22-2013, 07:06 PM   #18
ROTTEN
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In all this confusion of parts swapping did you do this combo?
2.5 tps
4.0 iac housing
2.5 iac

Or 2.5 tps
2.5 iac housing
4.0 iac

I tried moving things around until I got it correct. I don't have it anymore though.
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Unread 02-22-2013, 07:21 PM   #19
0verkillYJ
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The iac needs to go in far enough to bring the idle down to normal when the engine is fully warmed up. The warmer it gets the easier the idle is and the less air if needs so the iac will slowly close it to adjust the idle as it warms up.
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Unread 02-22-2013, 07:39 PM   #20
Que89YJ
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The iac goes through a calibration. The end of out is a switch. When the pndle pushes the switch into the hole out knows it is 0 and out and it adjust itself from there. That is why you need to do a battery reset when you change it.
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Unread 02-22-2013, 08:01 PM   #21
Drew_CarreyAB
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Az_zoner, the idle screw is underneath on the front drivers side. I had to adjust it like 3 times (which means taking TB off each time) and finally got it to 8-900 rpm, been that way for almost a year now and works and runs fine, for me anyways.
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Unread 02-22-2013, 08:30 PM   #22
0verkillYJ
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Mine is different. My idle is 100% controlled by the iac since I have a 95. I originally thought you were screwing out the iac plunger which you can also do to adjust idle, but it is not reccomended.
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Unread 02-22-2013, 09:04 PM   #23
az_zoner
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Quote:
Originally Posted by Drew_CarreyAB View Post
Az_zoner, the idle screw is underneath on the front drivers side. I had to adjust it like 3 times (which means taking TB off each time) and finally got it to 8-900 rpm, been that way for almost a year now and works and runs fine, for me anyways.
I found the screw but that looks like a stop so the air throttle plate does not over rotate. And if you go the other way you would be by passing the IAC's function by openning up the throttle plate.

Not sure if I want to mess to much with that.

cb
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Unread 02-22-2013, 09:08 PM   #24
az_zoner
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Quote:
Originally Posted by ROTTEN View Post
In all this confusion of parts swapping did you do this combo?
2.5 tps
4.0 iac housing
2.5 iac

Or 2.5 tps
2.5 iac housing
4.0 iac

I tried moving things around until I got it correct. I don't have it anymore though.
It might be possible one way but the 4.0 iac will not fit into the 2.5 housing. But the 2.5 iad will fit into the 4.0 housing and it is a very loose fit. So I do have the right corresponding parts together.

I'm going to buy a new 2.5 iac tomorrow and hope that the one I have is just bad and that will fix the issue.

thanks

cb
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Unread 02-22-2013, 09:15 PM   #25
az_zoner
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Quote:
Originally Posted by pete1991YJ View Post
Plug it in, start the jeep, and see if it moves in and out when you goose the throttle. IMHO that tip looks like its WAY too far away... maybe you can try different IAC's? I thought you had to use the same IAC that came with the throttle body?
I did give this a shot today but didn't start it. Just turned the ignition on and as hoping to see the iac move in or out. Also rotated the tps to see if that would have an impact on it movement. No movement. Which means it might be a bad IAC again. So like I said, I'm going to go buy a new one and give that I shot.

And it's not that I don't want to spend the 50 bucks. I'd really like to understand what takes place inside the housing.

Thanks all for the input,

Craig
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Unread 02-22-2013, 09:25 PM   #26
Que89YJ
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The iac moves to close the switch on the end of the pindle. From that point the ecu moves the iac in and out and the airflow is metered with the inputs from the map, cts, and tps to regulate idle. There are good youtube videos on it. The iac allows air to flow when your butterfly closes off the air flow to throttle body.
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Unread 02-22-2013, 09:27 PM   #27
ROTTEN
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Craig if you can wait until Monday I'll send you my 4.0 iac and housing if that's what your after. That's the same one I had on my setup and it worked.
I also have a good 2.5 tps that was in the setup. Man why did I sell that TB?!
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Unread 02-22-2013, 09:32 PM   #28
az_zoner
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Quote:
Originally Posted by Que89YJ View Post
The iac moves to close the switch on the end of the pindle. From that point the ecu moves the iac in and out and the airflow is metered with the inputs from the map, cts, and tps to regulate idle. There are good youtube videos on it. The iac allows air to flow when your butterfly closes off the air flow to throttle body.
That is exactly how I thought it would work. I'll have to look up the you tube vid.

Thanks

cb
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Unread 02-22-2013, 09:33 PM   #29
pete1991YJ
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Quote:
Originally Posted by az_zoner View Post
I did give this a shot today but didn't start it. Just turned the ignition on and as hoping to see the iac move in or out. Also rotated the tps to see if that would have an impact on it movement. No movement. Which means it might be a bad IAC again. So like I said, I'm going to go buy a new one and give that I shot.

And it's not that I don't want to spend the 50 bucks. I'd really like to understand what takes place inside the housing.

Thanks all for the input,

Craig
Didn't move, that's a pretty good sign it's toast IMHO. OTOH I see you have an offer for another housing and IAC, let's see what happens.
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Unread 02-22-2013, 09:39 PM   #30
az_zoner
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Quote:
Originally Posted by ROTTEN View Post
Craig if you can wait until Monday I'll send you my 4.0 iac and housing if that's what your after. That's the same one I had on my setup and it worked.
I also have a good 2.5 tps that was in the setup. Man why did I sell that TB?!
I have a 4.0 iac and housing that I tried and it was close to how I thought it should run with the exception that it seemed like when I let off the throttle it takes a little to long to come down to an 800-1000 rpm idle. I figured that was due to the larger pin and opening in the iac and housing.

Thanks for the offer. I think I'm going get it figured out tomorrow.

cb
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