Topic: What all comes off the 2.5 L throttle body; swapping to the 4.0L throttle body

[countryboy15]

What all comes off the 2.5 L throttle body when swapping to the 4.0L throttle body? I plan on doing the swap this weekend but I just want to make sure I know what to take off the 4.0 L  throttle body and replace with the 2.5 L throttle stuff. I don't know much about this type of stuff, and I figured I might as well swap to the 4.0 L throttle body since I have the part sitting on my wrecked jeep in my backyard. Thanks for any help you can give me.

[oldjeep]

Take the IAC off the old one.  Might as well swap the tps too since you know the one on your 2.5 is working.

Make sure you get a new TB gasket before you start the process.

[Bounty Hunter]

Be sure to swap the IAC housing, it's usually attached to the TB with 4 tamper-proof torx.

Are the two TB's similar as far as the MAP sensor attachment?  '91-'95 is different from '96-'04.

[countryboy15]

My good jeep is '91 models along with the wrecked jeep in my backyard.

[countryboy15]

I broke two torx bits already while trying to remove the throttle position sensor from both the 2.5 L and 4.0 L throttle bodys, any suggestions on how to do this without breaking anything else including the bolts holding it on.

[FourbangerYJ]

penatrating oil to loosen em up a bit.

[Bounty Hunter]

You can try a good penetrating spray like PB Blaster, but I think they are still prone to breakage if seized.

Let me know if you need anything, I've got a bunch of 2.5L, 4.0L, and 62mm throttle bodies, sensor bolts, sensors, etc.

[Jeffy]

The small torx use locktite so you can heat them up a little and they should break free,

[countryboy15]

I did the swap and now jeep wont start. It is turning over, when I put the pedal to the floor it just catches and jumps then immediately stops.

[countryboy15]

riGHT AFTER i DID THE SWAP IT STARTED. tHEN I KILLED IT TO CHANGE THE RADIATOR FLUIDS. aFTER i DID THAT iT STARTED BUT i NOTICED there was a clunking vibration coming from motor. I killed it to add more fluids, but after it didn't start how much more details are needed.

[sharpxmen]

you either unplugged something by accident or maybe the tps got damaged during the swap. check methodically all the connectors
tps
map
cps
camshaft position sensor
ignition coil
iat

as well as map vac line.

and a question, it won't stay at idle or it would die even with the throttle open?

[countryboy15]

IT bearly catches a spark with the pedal to the floor, but won't keep going. It would not start with me pushing the pedal to the floor. I am going to try and start it again today, if it dont I am going to check everything you said to. I couldn't get the TPS off during the swap so I left it on, even when I PUT WD-40 on it(I didn't come back to this website until I had reinstalled the 4.0 L throttle body .

you either unplugged something by accident or maybe the tps got damaged during the swap. check methodically all the connectors
tps= Throttle position sesnsor(right?)
map= map sensor (does a '91 2.5 L have a map sensor)
cps= is what?
camshaft position sensor= where is this located
ignition coil
iat= what is this?

as well as map vac line.    does a '91 jeep 2.5 have the map sensor as well as map sensor? if so where would I FIND this located at?

[Bounty Hunter]

A '91 2.5L does have a MAP sensor, it's located on the firewall above the valve cover, has a vacuum line and electrical connection leading to it.

Did you swap over the IAC housing (idle air control)?  It's on the passenger side of the throttle body and the only thing attached with 4 torx or tamper-proof torx bolts.  This housing needs to be swapped over as the 2.5L housing has a smaller bore than the 4.0L housing.  If you attached the 2.5L IAC to the 4.0L IAC housing then there is too much air moving past the IAC plunger.  (The IAC housing may have 2.5L or 4.0L embossed on the outside).

CPS is commonly the crank position sensor, it's located on the driver's side of the bellhousing just behind the exhaust manifold.  There is also a camshaft position sensor in the distributor but it doesn't commonly fail.

TPS is the Throttle Position Sensor and is attached to the front of the throttle body.

[sharpxmen]

iat = intake air temperature sensor - i don't think would make your engine not run at all (from what you are saying that's the case right now).

i'm leaning towards tps if everything else is plugged in properly. I would also check the map sensor vac line (see Bounty's post for explanation where it is located), the map sensor connector and the tps connector - these are things that you might have left unplugged and can [to a certain extent] cause the problems you describe

[oldjeep]

I'm working on this today.  Got one of Bounty hunters fancy TB and spacer kits.  Got the manifold ground out and unfortunately I realized that I don't have the security torx bit that I need for the IAC housing, so it's off to the store to find one.