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General Forums => The Mess Hall => Topic started by: rockalot1982 on January 17, 2008, 06:13:18 AM

Title: throttle body upgrade?
Post by: rockalot1982 on January 17, 2008, 06:13:18 AM
 :puzzled:  is the throttle body on a 4.0 interchangeable on a 2.5? Is there any performance plus? THanks
Title: Re: throttle body upgrade?
Post by: jcoleman on January 17, 2008, 11:23:12 AM
yes. http://www.creeperjeepers.org/throttle%20body%20swap.html)

The post Just a few down about weekend upgrades to the YJ has a little about throttle bodies too.  That's where i got the above link.
Title: Re: throttle body upgrade?
Post by: Jeffy on January 17, 2008, 11:26:00 AM
:puzzled:  is the throttle body on a 4.0 interchangeable on a 2.5? Is there any performance plus? THanks

A search here would have brought you this: http://4bangerjp.com/forums/index.php?topic=8.0
Title: Re: throttle body upgrade?
Post by: aka-justin on February 24, 2009, 11:33:21 PM
I just completed adapting a 4.0L Throttle Body from a TJ to my 2.5L YJ.  Only thing I had to do extra was capping off the extra MAP sensor port.  I have a lot more power at low RPM and while slightly depressing on the accelerator, but I'm noticing a small problem...

I noticed that it will stutter now when I punch it (More than prior).  I also have to slowly press down on the accelerator to bring up the RPMs up otherwise my power band turns into a power limp.  It has a fresh fuel filter, air filter, plugs, oil change, all the hoses are connected....

Any suggestions?  I'm going to try checking the and adjusting the TPS sensor this weekend. http://www.autozone.com/az/cds/en_us/0900823d/80/1f/e7/80/0900823d801fe780/repairInfoPages.htm (http://www.autozone.com/az/cds/en_us/0900823d/80/1f/e7/80/0900823d801fe780/repairInfoPages.htm)

Thanks,
Justin  :bandit:



Title: Re: throttle body upgrade?
Post by: Jeffy on February 24, 2009, 11:40:47 PM
Reset your PCM.
Title: Re: throttle body upgrade?
Post by: aka-justin on February 24, 2009, 11:50:30 PM
I'll give that a shot.

From what I read, I need to: disconnect the battery, let it sit for 15 min, then test drive it.

Thanks,
Justin
Title: Re: throttle body upgrade?
Post by: Jeffy on February 25, 2009, 03:25:43 AM
It may take a week or so for it to relearn what it need depending on how much you drive it.  Supposedly, if you ground the positive cable, it will drain any residual power in the capacitors faster.
Title: Re: throttle body upgrade?
Post by: wi1dweasal on February 26, 2009, 12:33:29 PM
quick question, can you take a throttle body from a 98 cherokee 4.0 and use it?
Title: Re: throttle body upgrade?
Post by: Jeffy on February 26, 2009, 12:40:38 PM
quick question, can you take a throttle body from a 98 cherokee 4.0 and use it?
Yes, it will work for your TJ.
Title: Re: throttle body upgrade?
Post by: aka-justin on February 27, 2009, 08:16:25 AM
It may take a week or so for it to relearn what it need depending on how much you drive it.  Supposedly, if you ground the positive cable, it will drain any residual power in the capacitors faster.

On the nose Jeffy; Thanks!.  Drove it about 100 miles last night and it now drives better.  No more bogging or stuttering.  It has more power with the throttle body than before, but it's no miracle; no more than 10 HP difference that I can feel.  I did notice it stopped slowing down so bad at slower speeds on hills and rough trails.
Diffently worth the $20 investment.   :bandit:

Thanks,
Justin
Title: Re: throttle body upgrade?
Post by: 89fourbanger on February 27, 2009, 11:35:32 AM
dumb question but if i do the 4.0 throttle body swap and want to do a throttle body spacer do i use a 2.5 and bore it out or a 4.0?
Title: Re: throttle body upgrade?
Post by: jfrabat on February 27, 2009, 11:58:01 AM
dumb question but if i do the 4.0 throttle body swap and want to do a throttle body spacer do i use a 2.5 and bore it out or a 4.0?

4.0L TBS for 4.0L TB; if you bore out the 4.0L TB, then it is better to get a 62mm spacer also...
Title: Re: throttle body upgrade?
Post by: Bounty Hunter on February 27, 2009, 06:53:07 PM
http://4bangerjp.com/forums/index.php/topic,4044.0.html
Title: Re: throttle body upgrade?
Post by: Jeffy on February 27, 2009, 11:39:03 PM
On the nose Jeffy; Thanks!.  Drove it about 100 miles last night and it now drives better.  No more bogging or stuttering.  It has more power with the throttle body than before, but it's no miracle; no more than 10 HP difference that I can feel.  I did notice it stopped slowing down so bad at slower speeds on hills and rough trails.
Diffently worth the $20 investment.   :bandit:

Thanks,
Justin
I think what really makes it worth it is just the throttle response.

dumb question but if i do the 4.0 throttle body swap and want to do a throttle body spacer do i use a 2.5 and bore it out or a 4.0?
There is no 2.5L TBS that I know of.  Either 2.5L or 4.0L should go with teh 4.0L TBS
Title: Re: throttle body upgrade?
Post by: cletz97 on April 14, 2009, 08:31:42 AM
do you have to change sensors with a throttle body for a tj?
Title: Re: throttle body upgrade?
Post by: FourbangerYJ on April 14, 2009, 09:24:01 AM
do you have to change sensors with a throttle body for a tj?

The sensors from your 2.5L go on to the bigger TB.
Title: Re: throttle body upgrade?
Post by: aka-justin on April 14, 2009, 11:04:18 PM
You have to swap the AIS and the throttle position sensor from your 2.5 throttle body to the 4.0 thorttle body.  The only difference between the YJ and the TJ is the Map sensor port.

Here's one of the many articles with more details about the swap.
http://www.4x4wire.com/jeep/tech/engine/throttlebody01/ (http://www.4x4wire.com/jeep/tech/engine/throttlebody01/)
Title: Re: throttle body upgrade?
Post by: Jeffy on April 15, 2009, 12:02:44 AM
do you have to change sensors with a throttle body for a tj?
Yes, at minimum the IAS needs to be swapped as well as the housing otherwise you'll get an internal vacuum leak and a high idle.
Title: Re: throttle body upgrade?
Post by: cletz97 on April 15, 2009, 08:03:00 AM
what if i don't have the sensors for the 4.0 throttle body?
Title: Re: throttle body upgrade?
Post by: Bounty Hunter on April 15, 2009, 08:56:38 AM
"what if i don't have the sensors for the 4.0 throttle body? "

You don't need them, use all 2.5 stuff on the TB.
Title: Re: throttle body upgrade?
Post by: st.chevrolet on April 15, 2009, 09:01:45 AM
You have to swap the AIS and the throttle position sensor from your 2.5 throttle body to the 4.0 throttle body.  The only difference between the YJ and the TJ is the Map sensor port.

Here's one of the many articles with more details about the swap.
http://www.4x4wire.com/jeep/tech/engine/throttlebody01/ (http://www.4x4wire.com/jeep/tech/engine/throttlebody01/)

Title: Re: throttle body upgrade?
Post by: cletz97 on April 17, 2009, 08:22:23 AM
ohhh alright haha
now i jsut feel dumb
Title: Re: throttle body upgrade?
Post by: cletz97 on April 27, 2009, 08:05:35 AM
the two AIS sensors on my throttle bodies are the same could i keep the one form the 4.0 on and use it? or do i have to still hange the houseing, i didnt before and its has a really high idle, so i guess today ill try using the sensor from the 4.0 instead of the 2.5 and see how that works out.
just has anyone else tried this?
mine both look like the one on the right (sensor plug in part)
Title: Re: throttle body upgrade?
Post by: jfrabat on April 27, 2009, 08:45:51 AM
the two AIS sensors on my throttle bodies are the same could i keep the one form the 4.0 on and use it? or do i have to still hange the houseing, i didnt before and its has a really high idle, so i guess today ill try using the sensor from the 4.0 instead of the 2.5 and see how that works out.
just has anyone else tried this?
mine both look like the one on the right (sensor plug in part)

Regarding the high idel, something you may want to check is the small hex screw that screws up from UNDER the TB that restricts the plate closed position; if set wrong, it can leave the plate open, causing a rough idle (I had this problem, and it was driving me NUTS).  Now, as far as the sensors, I would jut go ahead and use the 2.5L and avoid problems...
Title: Re: throttle body upgrade?
Post by: bjohn8758 on May 02, 2009, 03:10:18 PM
I'll tell you this much.... I put on a 62.5mm bored TB + a spacer and it did make a pretty big diiference in mid-range power. However. if you don't massage the exhaust (AIR IN AIR OUT) you won't notice it much..... I plan on working on the exhaust soon,

BTW....any ideas on flow??


"94 YJ
2.5
AX5
No other mods
Title: Re: throttle body upgrade?
Post by: jfrabat on May 02, 2009, 05:58:58 PM
BTW....any ideas on flow??

If you want to go all out, headers, high flow cat and cat back system is the way to go; but that can ge expensive.  I left the stock headers, and used a gibson cat back for some time, then my cat blew up.  I am now installing a Carsound by Magnaflow high flow cat and borla Stailess Steen cat back (all the crap from the cat ended up in my gibson muffler).
Title: Re: throttle body upgrade?
Post by: alfajeep on May 30, 2009, 08:54:43 AM
Ive noticed that after switching over to the 4.0TB, it takes longer to crank on cold starts.  Has anyone else had this problem?  I have reset the ECU after install, and its been 300 mi after the swap, going to try to go back to the 2.5 and see what happens.
Title: Re: throttle body upgrade?
Post by: jfrabat on May 30, 2009, 06:31:38 PM
Ive noticed that after switching over to the 4.0TB, it takes longer to crank on cold starts.  Has anyone else had this problem?  I have reset the ECU after install, and its been 300 mi after the swap, going to try to go back to the 2.5 and see what happens.

IIRC, it takes 50 warm-up cycles for the ECU to "learn"...