Carbureted to Fuel injection

[NorcalXJnewbie]

I am updating a 89 4.2 liter carb. wrangler to a 89 XJ 4.0 Renix engine swap.

I have the motor, harness and computer. My question is what terminals do i supply power to the computer with or does anyone have any insight on this swap.

Thanks much

 

[Johnnie Walker]

You should just be able to swap, everything over from the 4.0L to the 258.

 

[NorcalXJnewbie]

dont i need to hook up energy to the computer system on the new fuel injected motor?

 

[NorcalXJnewbie]

The 4.0 is also rated at 160hp vs 4.2 at 105hp

 

[Johnnie Walker]

So, to get this straight.. you are putting a renix 4.0L in a Wrangler or you putting a 4.2L in a XJ?

 

[Mr_Random]

Doesn't the wrangler have a firewall plug near the driver's side fender? If so, the renix block should plug right in! Otherwise you'll have to do some splicing... believe me, I know how this will go if you can't just plug it in, I'm in the midst of a TBI to MPI swap on my 2.5L... fun fun...

Why don't you pull the crank and connecting rods from the 4.2, drop them in the 4.0, and have a 4.5l?

There is alot of potential here, but honestly your questions aren't gonna be easily answered here on . I would suggest posting in the YJ section on jeepforum if you haven't already done it!

 

[old_man]

Upgrading a carbed motor to Renix entails several details that have to be addressed. First you need a bell housing that has a mount for the CPS. You need a flywheel or flexplate that has the CPS ring.

Your distributor needs to have a camshaft position sensor. The intake manifold has to be changed to mount the throttle body and sensors. With the Renix, you need to move over the ignition as well, to simplify things. This means swapping the ignition module and coil.

The good thing is that there is good manual on the Renix system and there are decent schematics available.

I did this on a 2.5L motor, then later upgraded to a 4.0L stroker.

Your best bet is to find a donor and absolutely strip the engine compartment. You will want the whole wiring harness and sensors. Don't forget that you will need an O2 sensor and MAP sensor. You can get a weld in bung for the O2.

 

[NorcalXJnewbie]

ok so here is the skinny....

we pulled the 4.2, put in the 4.0 along with the proper ax15 tranny, and bellhousing. I have the factory harness for our 89 4.0 and computer. I want to know what wires i need to run to the computer to get it to turn on and do its job aka run like a bat out of hell...

We are fiding things like fuel system, trying to get a newer model yj gas tank with fuel pump for FI, and make a new exhaust system. oh yeah the newer tranny has a different mounting pattern for the tcase shifter bracket too.

thanks all of yall.

 

[8Mud]

IMO your best bet is to spend a little extra and sign up for Alldata. They do a decent job with the Renix wiring diagrams and sensor troubleshooting. You can print out the applicable diagrams and have them right there with you.
The hot wires for the ECU aren't that difficult, but things in general can get confusing.