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5.2L Magnum XJ engine swap

YAAAHOOOOO!!! I'm really stoked! I was hoping to try to fire up the Jeep this past weekend but instead wound up tying up all of the loose ends which you can imagine can be pretty time consuming. Fuel lines, power steering hoses, trans cooler, exhaust, etc. Yesterday I went to install the belt and ran into a snag when I realized the A/C compressor from my Jeep has a 6 groove pulley and the Dakota has a 7 grove pulley system. I really wish I had some idea where the heck I put the compressor from the Dakota. :( The good thing is I was able to get a 6 groove belt in the same length so I'm running that for now.

Last night before I cut it off for the night I tried to crank the motor and when I turned the key on everything lit up but the starter wouldn't do anything when I turned the key to the start position. I pulled the starter relay and was able to crank the motor by jumping the relay. I figured I had some harness troubleshooting to do. Today after a little investigation I found that the shifter needs adjusting and the start circuit is working fine. I was able to crank the motor with the shifter in N.

One of the really strange things I found with this motor is that when I had it out and was checking it over the distributor rotor was 180* opposite of what it should have been. While I had the motor out and was cleaning it I also installed a new timing chain. When I did that I decided to install the distributor correctly and keep in mind when trying to start it for the first time that if it didn't start I may need to rotate it 180*. Tonight I cranked it over with the coil connected. At first just as I suspected the motor cranked but would not fire. I could smell some exhaust though so I figured turning the distributor 180* would likely help. I did that, got in the car, turned the key, and the motor fired right up! I was pleasantly shocked! I really thought I would have to do some trouble shooting of the harness before I'd get ignition. I may still have some troubleshooting to do, we'll see, but for now I am really excited!

B
 
NICE!

Get your gauges working yet? I'm really interested to see if they respond normally to the Dakota PCM as everyone expects...
 
That's great news! Do you just have the bare minimum hooked up right now or is everything else working too like interior lights, wipers, headlights, turn signals, etc.

The only wires you should need to get communication to the gauges are power and the CCD wires. Possibly a ground or two, as well.
 
TerraWombat said:
That's great news! Do you just have the bare minimum hooked up right now or is everything else working too like interior lights, wipers, headlights, turn signals, etc.

The only wires you should need to get communication to the gauges are power and the CCD wires. Possibly a ground or two, as well.
Click to expand...

So far everything appears to work. I haven't checked everything yet but for sure the interior lights work, brake lights, gauges, charging system, and starter of course. No check engine light on yet either!

Tomorrow I'm going to pull the shifter cable bracket and modify it so it'll start in park. I'll pour in some more antifreeze and then I'm going to see if It'll move under its own power.

B
 
kastein said:
NICE!

Get your gauges working yet? I'm really interested to see if they respond normally to the Dakota PCM as everyone expects...
Click to expand...

The gauges appear to be working perfectly. Voltage reads normal and oil pressure is good. I didn't run it more than a minute or so though so I'm not sure about the temp guage but I expect it will work also.

One thing amiss so far is that the fan is on shortly after the key is turned on, like about 10 seconds. I'll look into it tomorrow as well. That really isn't a big deal though as I am running no mechanical fan so I'd like to run the factory fan and the after market fan I have next to it in unison and control them independent of the ECU. So far my only problem with that is finding a spot for a separate temperate sensor. I was going to build one into the radiator but I had so many problems sealing up the pin hole leaks from Aluminum MIG welding that I didn't feel like creating another source of pin holes. I really need to get myself a TIG welder. :)

B
 
TerraWombat said:
How did the Dakota wiring harness fit into the XJ engine bay? Do you have any pictures of your current progress?
Click to expand...

The ECM on the Dakota is on the opposite side of the engine bay. So the fit is not great. About half the wire are too short and the other half too long. For the short ones I spliced in lengths of wire to make them longer. For the long ones I haven't done anything with them yet. The key is to completely unwrap the entire harness before you even start. This way not only can you trace any wire you need to but also you can run the wires the direction required.

I'm not sure you want to see pictures of the harness at this point. It looks down right scarey even to me! I'll get some pictures of it but I think I'll wait to post them until after I re-wrap it. That way you'll get the before and after pictures at the same time and you'll see that when all is said and done it doesn't look so bad.

B
 
Damn Bob, Got her going way before WF! :D
 
I'm sure I can handle it ;) This is where I'm at right now with my build (MJ w/99XJ interior wiring harness and 98ZJ engine bay harness.

CIMG2665.jpg


CIMG2663.jpg


I'm a sissy, though. I didn't want to take all of the wire loom off and unwrap everything. I'm just going to wind up running a bunch of wires along the back of the firewall to get wires to where they need to be.
 
Wow yours looks down right organized! :) I'll snap a pic tonight. Though unwrapping is time consuming it is reall helpfull. Especially when you consider they use certain wire colors for multiple circuits. Without unwrapping the harness it would be pretty hard to determing which circuit is which.

B
 
He has to make it past Iowa first......
 
tbburg said:
You know, if you have it that far apart, for that much surgery, there's another reason to unwrap the harness: to inspect the wiring. The wires chafe against each other inside the loam. Larrythedog built a Jeepspeed rig (posted the build thread in the jeepspeed forum: Sickdog Racing Jeepspeed Build)
When he stripped the harness to remove excess, he found a bunch of bare wire:
http://www.naxja.org/forum/showpost.php?p=245007179&postcount=230
Click to expand...

I didn't run into chafed wires on my 4.0L harness but I ran into quite a few wires melted together. My 4.0L only overheated once or twice because the original electric fan quit working. I'm pretty sure the melting was just from years of normal heat cycles. This could very well explain the intermittent misfires I had over the years. I'm not going to take the time to check the circuits in the old harness to see which ones could have been affected but you make a very good point.

One thing I've found with the Jeep wiring is that the wire they use is pretty poor. I know it's in their quest to use the thinest jacketed wire possible. For the most part these wires make it past the warranty, but as they age they can really be a problem.

One project I would love to do, and may after Winterfest, is make a completely new harness. All new wires, red for + and black for - and then instead of all of the wire colors use circuit number (the same numbers they use in the OEM wiring diagrams). If I did this, instead of having all of the splices in the harness I would do several terminal strips. There really are too many major splices in there harnesses which is another point of failure. The only reason I may not do this, beside the amount of work it would take, is the cost. The cost of what I have now was pretty much $0, a few thousand feet of wire and all new connectors (or at least connector pins and sockets) may end up being cost prohibitive. Not to mention the huge amount of work required the find all of the correct pins and connectors. But I can still dream! :)

B
 
So I fired it up again tonight after redoing my shifter cable bracket. I pulled it out of the garage and drove it up and down the driveway. I didn't have my auxillary fuse panel installed yet so I had no headlights and it was dark. It moved under its own power! I also did a smokey burnout because I'm very childish! :) The motor got up to 180* but didn't go over even though I let it idle for about 10 minutes. No leaks so far and no MIL either. Tomorrow I'm going to take it down the road to see of the trans shifts properly. I'm also going to connect my OBDII scanner and check to see that all of the sensors are working. I am really excited!

BTW, with the 4.0L and 35" tires there is no way I could ever break the tires loose much less do a smokey burnout!

B
 
ChiXJeff said:
He has to make it past Iowa first......
Click to expand...

Getting through Iowa is a piece of cake. Getting through Nebraska, that's an entirely different story. I'm not sure why but nearly every break down I've had has been in Nebraska.

B
 
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