98xj 5.3 swap (the poverty method).

[blistovmhz]

Right on man. One piece of advice. See if you can fit the np241c under there. Can grab one for $100 (or free), bolts right on, is substantially stronger than the np231j, and will save you money on adapters. I don't know why no one does this. Maybe because the SYE's are sometimes hard to get ahold of (I think JBConversions is the only game in town, and they can be flaky about stocking anything). But, if you can get the SYE for it, it's only $300 vs the $700 for the GM/Jeep adapter.

I'm just starting another build right now. 85 4runner, another 5.3/4l60e, probably the 241c for now unless an Atlas shows up, Land Cruiser BJ60 front axle and LC BJ60 rear with Toyota mini tubes and outers (for center).
My plan this time is to just use the entire GM PDC. This way there's almost no wiring to be done. Just give the PDC power, connect the brake switch to the PDC, and plug it all in and done. Gives you a ton of extra fuses and relays for auxiliary stuff and saves me a day of wiring.

Oh, also... Depending on your lift (or oil pan choice), you might wanna just do the motor mounts yourself. Novaks mounts put the engine unfortunately high up. Do some measuring, but I think the motor could be 2" lower than Novak puts it. Lower COG/RC and you could probably clear the stock hood.

 

[Lake919]

Hey thanks for the great advice. How difficult would it be to get rid of the XJ harness all together and just go with the GM harness and ECU? My XJ is a 1995

 

[blistovmhz]

When you swap in the 5.3, you're throwing out the entire XJ engine harness, unless you plan on plugging in all the XJ sensors into the 5.3 to send data to the Jeep ECU to use as a gauge mule. If you're just going to put in a GM cluster, or use a tablet though, the entire Jeep engine harness gets tossed.

If you decide to go with the GM PDC as well, you just take all your auxilary stuff out of the Jeep PDC and run it into the GM unit. Most of the stuff is the same. Mostly headlights, a few battery + and ignitions.
Realistically, re-working the GM harness to work with the Jeep PDC is pointless because there's not enough room for the number of relays and fuses you need for the GM engine and ECU so you end up just building another PDC on the firewall. Using the GM PDC, you keep everything all in one place, wire Jeep stuff into it, and plug in the GM ECU as well. The GM PDC is modular. All engine stuff is on a single connector to the PDC. Same goes with all interior stuff. Everything is well organized and segregated as it should be.

 

[cleenrob]

That's awesome. After reading your thread and photojareds I have decided to pull the plug. I bought a 6.0 with 45k on the clock and a 4L65E for 1400 delivered to my door.


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lucky, i can hardly even find 5.3/4x4 pullouts in my area.

 

[cleenrob]

Hey thanks for the great advice. How difficult would it be to get rid of the XJ harness all together and just go with the GM harness and ECU? My XJ is a 1995

on your 95 you wont need the ecu as a gauge mule, the cluster is stand alone from the ecu, you need the sensors and the wires that plug in to them and thats it, just plumb them into the 5.3 block and they will rea dlike factory

the tach takes extra effort but can be used

 

[Lake919]

My family owns a large Chevrolet dealership. I get great deals on parts.


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[PhotoJared]

on your 95 you wont need the ecu as a gauge mule, the cluster is stand alone from the ecu, you need the sensors and the wires that plug in to them and thats it, just plumb them into the 5.3 block and they will rea dlike factory

the tach takes extra effort but can be used

Not to mention passing smog will be a HELL of a lot easier

 

[Lake919]

What is smog? I live in Alabama. No such thing.


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[kastein]

on your 95 you wont need the ecu as a gauge mule, the cluster is stand alone from the ecu, you need the sensors and the wires that plug in to them and thats it, just plumb them into the 5.3 block and they will rea dlike factory

the tach takes extra effort but can be used

Agreed.

Stuff on a 96-down XJ cluster:
- voltage. Leave it wired how it is
- coolant temp. A 1-wire sensor with a 1/8 NPT thread runs this, just plumb it into the chevy engine wherever it fits
- fuel level. Doesn't even touch the engine electrical system, leave it how it is
- oil pressure. Another 1-wire sensor with a 1/8 NPT thread here, just plumb it in
- speedo. This one's run directly off the VSS on 91-95, direct mechanical drive on 90-down. Leave it wired how it is unless you switch to the 40k counts per mile (I believe) Chevy one, then you have to do something custom to make it work right again.
- tach. This one's a little tricky if you want your stock tach to work, I'm picky that way. The stock signal is (IIRC) 2 pulses per engine revolution. The FSM will tell you more, it has a table. I forget what voltage it is. It would be pretty trivial to build a little converter circuit that would take the tach signal from the Chevy ECU or failing that, ignition coil trigger pulses from one or more coil packs and produce a Jeep instrument cluster tach drive signal from it.

Other fun stuff - the MIL, GEN lamp, and upshift lamp are all in the cluster as well. I can't remember if they are +12 to turn lamp on or ground wire to turn lamp on, but shouldn't be hard to rig something up to make the Chevy ECU use them too if you really want to.