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Unread 10-26-2014, 07:22 PM   #1
cdtaylor02
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junkyard MPFI swap

Well as the title says I would like to do the junkyard MPFI swap from a 4.0. I am FED up with attempting to get my weber right, I think I have it, runs decent for a couple days and back to crap it goes. I'm done with it.

I have done research on both a TBI as well as the MPFI. I think im settling on the MPFI but I would like to hear from those that accomplished it. I love a challenge and it sure seems like one, however I don't want to fall in a black hole with it

I am curious about what came up that you weren't expecting as well as other issues along the way. I think the electrical is the most intimidating to me so if you have experience with that please let me know

I have found one other thread on this and it was well written but I would like to get others perspectives

Thanks
Chris

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Unread 10-26-2014, 07:41 PM   #2
TIPPEDITOVER
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Read

http://www.jeepforum.com/forum/f8/ca...-swap-1530716/

http://www.jeepforum.com/forum/f8/of...thread-475002/
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Unread 10-26-2014, 08:06 PM   #3
cdtaylor02
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Thanks for the thread. There is at least 2 days worth of reading on that one for wiring.
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Unread 10-26-2014, 08:32 PM   #4
TIPPEDITOVER
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Both of those threads answer most, if not all questions about the 4.0 swap. No need to re-invent the wheel and you can use them as a reference as you go. You could even try PM'ing the original authors, or those involved. They might still be around and willing to help.
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Unread 10-27-2014, 08:10 AM   #5
ThisGuyUKnow
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Something like this?
rps20141027_100913.jpg  
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Unread 10-27-2014, 08:25 AM   #6
cdtaylor02
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Yes but minus the 4.0. I don't want to swap engine or head, just the FI I have a post saved that accomplished it, just looking for others that did it and what there thoughts and experiences were
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Unread 10-27-2014, 10:34 AM   #7
TIPPEDITOVER
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Oh I was mistaken about what your end goal was. Well, good luck to you
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Unread 10-27-2014, 10:47 AM   #8
cdtaylor02
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Oh its no problem, thank you for the info that you gave me. Same thing really I guess.
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Unread 10-27-2014, 11:20 AM   #9
SLO_Ken
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Yep, all the electric and plumbing details will be the same whether you are dong a complete engine swap, swapping a 4.0 head on to your 258, or just replacing the intake with an MPFI unit. As far as mechanically bolting everything up, there are some slight differences between the 258 and 4.0 intakes. Most notably, the 258 is warmed by the coolant, so you'll need to re-route your heater hose directly to the water pump. Also, the 258 power steering brackets do not directly bolt up to the 4.0 intake. Some slight modification is needed. And, I believe there is an issue with interference between the 4.0 intake and the cast iron 258 exhaust manifold. But I'm not clear on the details, as I haven't actually done this swap.

You'll need an electric fuel pump. MPFI runs on 38-50psi (depending on which mpfi system you go with), compared to the 5-10psi that is typical of carb setups.

As TIPPEDITOVER mentioned earlier, if you have any questions regarding getting the wiring and fuel lines figured out, there are many of us that have been there and are willing to offer advice and assistance.

Good luck and have fun!
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Unread 10-27-2014, 11:26 AM   #10
cdtaylor02
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That's great!! Thanks for the info. Gonna grab a harness tomorrow and work that out over the next couple weeks I figure I can work my way around the mechanical issues, not a huge fan of wiring though
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Unread 10-27-2014, 05:03 PM   #11
cdtaylor02
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Im curious if any of you used the evap canister from the 4.0. Seems like it would be needed but im running an engine with 2 lines so not to sure
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Unread 10-27-2014, 05:43 PM   #12
SLO_Ken
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Yes, I did use the 4.0 evap canister. You can use your original canister as well, if you are not concerned with meeting emissions requirements.

Oh, something else I just thought of.. you will want/need the 4.0 thermostat housing with the threaded bung for a temp sensor.
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Unread 10-27-2014, 09:58 PM   #13
cdtaylor02
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Thanks for the reply. I am not concerned with emissions and i dobt have obe on my jeep right now so gonna have to yank it from a doner. Tracking the housing to accept the temp sender, thank you. I'm feeling pretty confident about this, knowing that it has been done and all of you that have the knowledge to help fix me when I break it. Why not go for it
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Unread 10-28-2014, 10:57 AM   #14
ThisGuyUKnow
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[quote=SLO_Ken;26303474]Yes, I did use the 4.0 evap canister. You can use your original canister as well, if you are not concerned with meeting emissions requirements.

Oh, something else I just thought of.. you will want/need the 4.0 thermostat housing with the threaded bung for

I grabbed the evap can from a yj. I can't find good info on how it is plumbed, the gas tank is obvious but on diaphragm what do the two nipples go to? One tothe intake and one to....? ?
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Unread 10-28-2014, 11:01 AM   #15
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If you are gonna just trash that Weber, you could always ship it to me. I wouldn't mind having a spare.
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