It's Time to SUPERSIZE Moby - MoTech 6.2L LS Jeep Motor Swap

Okay, so it turns out that Moby was the easiest to fix and the fastest. With some help from Motech, we were able to determine that there was some kind of short in the JK temp sensor wires. When we had run the wiring harness during install, we had routed it between the motor and firewall and later found there was some damage done to it. This initially caused an issue with the tach and appears to be the source of our problem this time. Rather than pull the whole loom apart, Robbie and I talked about it and decided that the easiest thing to do was to cut the positive lead and run a new wire to the sensor. Being that the crank sensor shares the same ground wire, we decided to leave that alone. After doing a quick check, all looked good again and after a quick test drive, found everything to be working perfectly. Now I just have to spend some time cleaning things up and routing the new wire.

Here's a shot of me locating the temp sensor wire on the main plug going into the JK PCM.
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Soldering on a new wire.
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Clipping the positive lead on the temp sensor plug.
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Getting a good signal again.
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Thanks for all your help Motech :thumb:
 
Good news. :rock: And your off to the races....literally. With some luck, I'll catch you out there Friday. :thumb:
 
Glad to see it was simple! So I was just wondering, is it not possible to use an ODB code reader anymore on Mody, or are the only codes it will pick up are for the JK side of the house? :thinking:
 
Skid_Kid said:
Glad to see it was simple! So I was just wondering, is it not possible to use an ODB code reader anymore on Mody, or are the only codes it will pick up are for the JK side of the house? :thinking:
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Oh no, you definitely still use the OBDII reader, you just now have 2 of them - one for the JK PCM and one for the GM. I was reading from both of them.
 
Cats

CarsonCindy said:
New GM cats for Moby. Thanks Derek for your help getting these!

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Im doing the MoTech swap also, what is the part # for the cats? Are they for a Trailblazer SS?
 
That is the stock truck exhaust. Problem is its configured for passenger side exit. Needs to be re-configured to exit drivers side. You can use Trailblazer exhaust manifolds which is what I changed to for clearance of upper arm passenger side. I also used 2004 Suburban exhaust for better clearance since it doesn't drop down as far as truck setup but also needs to be re-configured. If I did it again I would just get the Motech setup from Robbi and not have to do any re-configuring. Most important part is make sure you don't have any exhaust leaks. Just a tiny one effects your O2 reading and causes a rich condition. Good Luck!
 
wayoflife said:
A manual was an option but one we decided against - more because we would really start to break stuff than anything but, also because wheeling on really hard terrain in an auto is just so much easier. :cool:
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That's a really great automatic transmission, too!
 
wayoflife said:
Yup, what he said and yup, it's amazing. Also, unlike a HEMI, it fits in the JK engine compartment WITHOUT having to beat up your firewall.
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I can't believe that is all the weight difference, and that is another big plus not having to beat the fire wall up. It seems the LS is the way to go.
 
wayoflife said:
Yup, what he said and yup, it's amazing. Also, unlike a HEMI, it fits in the JK engine compartment WITHOUT having to beat up your firewall.
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I believe I've heard MoTech say that the LS doesn't get as hot, either. I know Moby isn't set up for gas mileage, but they get really good mileage for such a powerful V8 motor.
 
notnalc68 said:
I believe I've heard MoTech say that the LS doesn't get as hot, either. I know Moby isn't set up for gas mileage, but they get really good mileage for such a powerful V8 motor.
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This is true. EVERYONE I know with a HEMI has over heating problems or have to run a powerful fan that sound like a jet engine and prevents you from hearing the great motor all the time to help keep it cooler. The LS we have is still running our factory fan on a Griffon radiator and everything runs cool. We did have a tach issue once and a temp sensor wire issue once that caused over heating but both were simple problems to track down and easy to fix. Haven't had an issue since.

As far as MPG goes, before the motor swap, we were getting about 8-10 MPG at best with our 3.8L motor pushing our JK that weighs about 7000 lbs. and riding on 40's. Now, we average about 10-13 MPG and could easily get more if we drove slower so yeah, the fuel economy is much better and we get a lot more power to boot. :yup:
 
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