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Old 07-21-2010, 02:50 PM
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Question Throttle Body Spacer

I have a 2003 Wrangler with a 4.0 auto. I recently installed an Air Raid cold air intake along with an Air Raid throttle body spacer. I installed the cold air intake first then about a month later, I installed the throttle body spacer. Hence my problem, after installing the throttle body spacer, my transmission started to shift earlier than it was supposed to. Does anyone know what causes this and most important, how to fix this?
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Old 07-21-2010, 02:53 PM   #2
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step 1 - remove above parts.
step 2 - replace w/ OEM parts
problem solved.

in all seriousness, TB spacers/CAI have proved themselves worthless on the 4.0L

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Old 07-21-2010, 03:06 PM   #3
Knows a couple things...

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X2, such products are a 100% waste of $$$ when installed onto the TJ's 4.0L engine. Neither is the cause of your change in shifting.
When you have a choice, buy American.
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Old 07-21-2010, 03:06 PM   #4
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Retired my 94 YJ 4cyl 5spd @ 200K
Now in a 04 TJ 4cyl 5spd CV @120K+
Both as a commuter vehicle in NW, NJ
April 2012.downsized and now a 99er.
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Old 07-21-2010, 05:15 PM   #5
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I agree and disagree with the above posts.

I agree that the CAI and TB spacer do little good, if any, on a 4.0. But go one more step, by adding a 62MM throttle body(stock is 60MM intake necked down to 56MM), and it DOES improve throttle response. Maybe no more actual horsepower or torque, but response......heck yes.

It is annoying though, with the whistling. But worth it for me on my trail only rig when I need to "get some".

If I would not have gotten the TB and spacer for free though(a friend took it off of his DD because it was too touchy), I would not have wasted the $$$ to do it.
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Old 07-31-2010, 09:18 AM   #6

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My mods worked good so I really have no idea why you guys keep telling people not to do any to the 4.0?
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Old 07-31-2010, 09:26 AM   #7
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Jerry, perhaps you can confirm or deny this...I've never so much as looked under the hood of a Jeep with an auto tranny and I'm far from a mechanic (all book knowledge from reading the experts' posts on forums) so this may not even be plausible.

On my old Dakota, there was a TV cable (aka kickdown cable) for the tranny hooked to the throttle body which would control both upshifts and an extent. What is the likelihood that either the tb spacer slightly changed the length of that kickdown cable causing it to be out of adjustment, or that it was knocked out of adjustment while working on it. Or is this cable not even present on the Jeep transmissions?

Originally Posted by jeepjones View Post
My mods worked good so I really have no idea why you guys keep telling people not to do any to the 4.0?
They're not saying don't mod the 4.0...they're saying don't waste your money on these specific useless mods on the 4.0. The Jeep's stock intake flows more than enough air for the engine to handle so increasing airflow is useless since they engine CAN'T take anymore in. On the 4.0, throttle body spacers are nothing more than an oversize paperweight. A bigger throttle body would probably help some as mentioned above...although you do need to be careful. If you go TOO big, your low end torque will start dropping off. Can't remember the reason why but it was a big issue for V6 Dakota owners who were putting V8 throttle bodies on their trucks. Stock on the Dakota was like 42mm...going up to 46 or 48 helped tremendously in low end torque, acceleration, and top speed. Going over 50mm caused a lot of people to notice bigger changes in the top end, but their trucks lost low end torque and bogged down off the line. Once they got into the powerband though, they could feel them really start to take off. Even with a larger throttle body, I don't think a new intake would be necessary...the stock one probably could flow more than enough air even for the new throttle body to handle.
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Old 07-31-2010, 09:33 AM   #8
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not to start a bickering session... but these bolt-on mods, barely work on engines tuned for performance and speed. There is nothing, at all stock on the jeep that is tuned for performance and speed :P Not to mention the intake and exhaust system of TJ's are pretty well engineered to begin with. With the 4.0 you are MUCH better off spending the money on really good replacement parts, and keeping everything lubed, adjusted and replaced when needed, then you are spending hundreds of dollars on parts, that will show you VERY little difference if anything.
Hook your jeep up to a Dyno, before, then install the CAI and spacer, and hook it up again... (ironically the 2 dyno times will cost less than your intake :P) Then replace your parts with new OEM parts, and enjoy driving that refridgerator box for thousands of miles

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