Topic: I know it's possible, but how hard? (MPI swap from TBI)

[Mr_Random]

I want to change my crappy TBI to MPI before summer, and have a good idea of what it will take, but would like some advice on it first.

I can get the intake manifold, fuel rail, throttle body (probably just use a 4.0), and wiring harness w/ ECU for somewhere on the order of $300.

I could get the sensors pretty cheap, but mine are all working and I would like to know which one's can swap over (other than CPS, because it's nonexistant on mine).

Speaking of the CPS, how would I mount it? and would I need a new flywheel or whatever it uses to read TDC for each piston?

I'm good with all things electrical (my dad is an electrical contractor), so this will be pretty feasable for me electrically. I'm not quite as good with mechanics, but I learn quick and am sure I can do anything there as well.

Anyways, anything else I should know/consider?

Oh, also planning an electric fan swap, but that won't be as much of a challenge...

Oh, just so you know, this is an 86 XJ 4cyl

[Mr_Random]

Sorry for DP, but it won't let me edit!

EDIT: My speedo is cable, right? Will I have to change to electronic if it's a 95 wiring harness?

[impboy65]

I'm doing the same thing to my 90 YJ and I have to change EVERYTHING! I used a 92 YJ as a donar and I had to use every bit of wiring harness, gauges, sending units etc. Now I prett much have a 92 YJ.

[Mr_Random]

I'm doing the same thing to my 90 YJ and I have to change EVERYTHING! I used a 92 YJ as a donar and I had to use every bit of wiring harness, gauges, sending units etc. Now I prett much have a 92 YJ.

oh yeah, and fuel pump... haha... so I assume quite a bit of stuff, but how much work/ how technically challenging was it? and what about the CPS? how did/are you dealing with that?

[Mr_Random]

DUH... I'm stupid, and obviously don't know enough about my jeep's tech, I already have a CPS! so this will be easier than I thought, but still, anyone want to give advice?

[impboy65]

Well in my build, I'm taking the motor too. look it up in the members projects section. dirks 90 yj rebuild.

[Mr_Random]

I saw that, but I'll go back and see if you've updated at all... my project is a little different, but I guess revolves around the same lines of getting/installing the new wiring harness, ecu, and fuel pump/fuel tank, but after that it's a bit different...

I wonder, I've seen pictures of engine bays for 4cyl/6cyl Wranglers and 6cyl cherokee's, and there are cables that run over the head of the engine, what are those for? TBI systems don't seem to have them... I'd like to know if they're crucial to MY build...

[Mr_Random]

stupid edit doesn't work, so here's what my edit to the last one would look like if it did work:

EDIT: well, obviously they are crucial, they're throttle cables! It looks like I'd have to reroute my cables from the firewall, as the lever looks like it turns opposite across the different TB's... I was also worried about the T-stat, but it looks like the different head cover design over the years doesn't matter much.

So that means I pretty much know what I need for fuel delivery and electronics, but I have to study my chilton for more info on the vac components that I might need...

I also need a plan to make everything look like it isn't just a botched, redneck job.

Well, looks like I'm just turning this into a journal of sorts... might as well continue...

The engine is knocking and being generally goofy, so I predict a rebuild also, I want to do it all myself and update everything to make it run like a 2008 2.5L (if they existed), along with the MPI conversion. The clutch is also shot,  but I already have a new kit for it, so I'm thinking I'll just get more parts to redo everything from there forward.

I'm thinking new;

rockers, lifters, springs, and valves.

If I want to stay stock, I'll leave the pistons and crank, with new piston rings.
Anything else there I should also note?