06 TJ Engine And Transmission Swap

Duner

Duner

Doonigan
Original poster
Supporting Member
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May 6, 2020
Messages
341
Location
Buffalo, New York
Hey all. So I haven’t seen a “master” thread that answers a lot to common questions I’ve seen/ I have myself.

I’m looking to engine swap/upgrade from a 2.5 to a 4.0 in my 06 TJ. From my original thread, I wanted to do a complete swap from a 99 into the 06, but I’ve since seen better options.

I’ve heard 03-04 engines/transmissions are pretty much “plug and play” for the harness of an 06.

I want to explore what options I have and get compatibility clarity.

Obviously going to a 4.0 from a 2.5 means changing engine mount positions.

First, what years of engines are compatible without major compatibility issues?

With going to a 4.0, what changes need to be made? (Here’s what I’m aware of)
- harness
- engine mounts

Assuming 03-04 4.0 is the most “plug and play” compatible, what’s the best transmission option? Is an ax-15 conversion a good choice?

Currently I have a manual transmission, if I go to a different year/ an auto trans, what needs to be changed? PCM/ Mounts?


Feel free to link threads that may contain this info/ share whatever knowledge you have to offer.

Thanks guys,

Matt
 
Last edited:
05 and 06 are different than earlier versions. Different PCM, different cam sensor tone wheel, different crank sensor pattern on the flywheel.
 
JKP said:
05 and 06 are different than earlier versions. Different PCM, different cam sensor tone wheel, different crank sensor pattern on the flywheel.
Click to expand...

Does that mean a 06 wiring harness would need to be modified for those to work? Or is there a computer, such as the PCM, that reads that information that would need to be replaced? I’m not super familiar with specific component functions.
 
Not that I have any direct experience...but in my reading of posts and doing research prior to purchasing my 97 4.0...a 2.5 to 4.0 swap might and probably will cost more than an LS swap.

-Mac
 
macleanflood said:
Not that I have any direct experience...but in my reading of posts and doing research prior to purchasing my 97 4.0...a 2.5 to 4.0 swap might and probably will cost more than an LS swap.

-Mac
Click to expand...

Are you sure? I’m ignorant to LS swaps, but from what I’ve seen in my brief stumbling across of threads they are very expensive. A thing to consider is I wouldn’t be buying a brand new, remanufactured engine/trans. It would be used, which maybe you already considered in your comment. Thanks
 
An 05/06 PCM will require the appropriate 05/06 flywheel and cam sensor to work.

An older engine would require the above parts to be swapped to it to work with the 06/06 PCM.

No idea on harness compatibility.

You're probably better off selling the 4 cyl Jeep and buying a 6 cyl one moneywise.
 
JKP said:
An 05/06 PCM will require the appropriate 05/06 flywheel and cam sensor to work.

An older engine would require the above parts to be swapped to it to work with the 06/06 PCM.

No idea on harness compatibility.

You're probably better off selling the 4 cyl Jeep and buying a 6 cyl one moneywise.
Click to expand...

This is where I lack knowledge on internal electronics, such as the dash gauge cluster, and other key electronics components being compatible from different years. If I slapped in an 03-04 engine/transmission/PCM, the components, electronically speaking, that I am unsure of being compatible are the harness and the two sensors you listed.

Do you have any info on an LS total cost? Some guidance is much appreciated.
 
macleanflood said:
Not that I have any direct experience...but in my reading of posts and doing research prior to purchasing my 97 4.0...a 2.5 to 4.0 swap might and probably will cost more than an LS swap.

-Mac
Click to expand...

From what I've read a 318 swap shouldn't be far different cost wise than a 4.0.

I don't know that an ls would be cheaper than a 4.0, huge advantage to the 4.0 is everything is figured out and available used. PLENTY of rusty frame TJ's to pull mounts from, locations, etc.

Perhaps find a broken frame 4.0 TJ?
 
Strazi said:
Hey all. So I haven’t seen a “master” thread that answers a lot to common questions I’ve seen/ I have myself.

I’m looking to engine swap/upgrade from a 2.4 to a 4.0 in my 06 TJ. From my original thread, I wanted to do a complete swap from a 99 into the 06, but I’ve since seen better options.

I’ve heard 03-04 engines/transmissions are pretty much “plug and play” for the harness of an 06.

I want to explore what options I have and get compatibility clarity.

Obviously going to a 4.0 from a 2.4 means changing engine mount positions.

First, what years of engines are compatible without major compatibility issues?

With going to a 4.0, what changes need to be made? (Here’s what I’m aware of)
- harness
- engine mounts

Assuming 03-04 4.0 is the most “plug and play” compatible, what’s the best transmission option? Is an ax-15 conversion a good choice?

Currently I have a manual transmission, if I go to a different year/ an auto trans, what needs to be changed? PCM/ Mounts?


Feel free to link threads that may contain this info/ share whatever knowledge you have to offer.

Thanks guys,

Matt
Click to expand...

Swapping in the I6 for the 4 banger is far from plug and play. While certainly possible, in general it is not a simple nor inexpensive swap. The successful swaps I have seen - in terms of compatibility and cost - all have started with a complete donor vehicle to source all the necessary parts.

Also, I see you are in New York. Is there emission testing in your county? In general, Federal requirements on engine swaps call for engines that are at least the same year or newer than the vehicle.
 
Shank said:
From what I've read a 318 swap shouldn't be far different cost wise than a 4.0.

I don't know that an ls would be cheaper than a 4.0, huge advantage to the 4.0 is everything is figured out and available used. PLENTY of rusty frame TJ's to pull mounts from, locations, etc.

Perhaps find a broken frame 4.0 TJ?
Click to expand...

That’s what I have heard too. The tricky part is identifying components that are/ aren’t compatible. I almost want to suffer through it and figure it out so I can create a master guide to save others time and money :D
 
NashvilleTJ said:
Swapping in the I6 for the 4 banger is far from plug and play. While certainly possible, in general it is not a simple nor inexpensive swap. The successful swaps I have seen - in terms of compatibility and cost - all have started with a complete donor vehicle to source all the necessary parts.

Also, I see you are in New York. Is there emission testing in your county? In general, Federal requirements on engine swaps call for engines that are at least the same year or newer than the vehicle.
Click to expand...

I do have a 99 donor I could use, and NY does have some emissions compliance, but from what I’ve seen it hasn’t applied to engine years. Now I’m curious if the shop that said they would do the entire swap knows of a way to work around that law, like putting the VIN from the 99 on the 06? Lmao
 
It looks like swapping the 2.4 out for a 4.0 is difficult. I need to replace my 2.4 powertech. I can’t find one anywhere. The 4.0s seem to be everywhere, so I’ve been considering that. Does anyone have any suggestions? It would be much appreciated!
 
Colton.simoneau said:
It looks like swapping the 2.4 out for a 4.0 is difficult. I need to replace my 2.4 powertech. I can’t find one anywhere. The 4.0s seem to be everywhere, so I’ve been considering that. Does anyone have any suggestions? It would be much appreciated!
Click to expand...

From what everyone else says, either use a complete donor vehicle for your swap, do an LS swap, or sell off the Jeep and get one with the engine you want.

I’m in the same boat as you in terms of swapping an engine, might just swap everything from the 99 into the 06, but I’m not sure if the transmission mounts are the same.
 
Shank said:
From what I've read a 318 swap shouldn't be far different cost wise than a 4.0.

I don't know that an ls would be cheaper than a 4.0, huge advantage to the 4.0 is everything is figured out and available used. PLENTY of rusty frame TJ's to pull mounts from, locations, etc.

Perhaps find a broken frame 4.0 TJ?
Click to expand...

The issue for the OP is that he's dealing with a 2006 vehicle and they stop manufacturing the 5.2 in 2002 & the 5.9 in 2003 so neither engine would be considered a legal swap in a newer vehicle. Federal laws require that you use a engine from the same year or newer for a legal swap.

Now if it was a older TJ then I would agree that for the trouble of swapping in a 4.0 you coulda had a V-8...

Strazi said:
That’s what I have heard too. The tricky part is identifying components that are/ aren’t compatible. I almost want to suffer through it and figure it out so I can create a master guide to save others time and money :D
Click to expand...


I'm not sure what components you are referring to? There are enough threads & YT videos on doing the magnum swap that I think it's all pretty well covered.
 
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