SAR JK r2.8 Cummins conversion

superbuickguy

Explorer
Congrats! it sounds really small.
I do believe a 4 cyl diesel is ideal for the JKn

-Da
I know I overkilled the transmission but it isn't my driver - and I don't want to ever have to rescue my wife when it's what I sourced that breaks. I also plan on turning this up after the year warranty - so I think it'll be just fine for her while giving me peace and peace of mind while she's out search and rescuing
 

superbuickguy

Explorer
and wiring continues until the world ends
LOxfJMph.jpg


where I'm at. I've got nothing accomplished. The ignition switch will power the motor and turn it off, however, getting it to engage the starter has been a challenge.

I'm stepping back from that - worst case scenario, it gets a button... but I have a lot of other things I can do, so I'll continue to mess with it while I go onto my next challenge - wiring the fan to work. Once that is done, it actually could be driven on the road. Speedo works, all the dash emojis light up (festive) even ones I didn't do anything with (sway bar disconnect error light).
 

superbuickguy

Explorer
with how much this motor costs, I'm surprised you have to go aftermarket to get the flange
Iui8gN6h.jpg

not just that but the m10x1.25 nuts aren't included for the exhaust...
and that other piece... 60 bucks... no
installed
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304 16 ga stainless
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and tips
w6MsQfEh.jpg

I didn't finish because I am out of oxygen for my torch - need to make and install hanger - all of which require a 90 degree bend
also fixed the jack on my trailer so I can haul it to a friend to figure out the ignition situation
SthLCsFh.jpg


ignition powers on, but won't crank. Occasionally it does but then shortly after that it won't crank at all (even with a bypass).... also plumb the A/C

a bit of an explanation since most don't know me here .... I have backup plans if stuff doesn't work. The ignition thing - this is the 2nd lowest intervention. I'll rewire the entire rig to make this work but I'd rather not (since that means probably no abs, new dash and several issues with the HVAC system since it's all CanBus).
 

Dan Grec

Expedition Leader
Tricking the JK into thinking it has a "running" engine was quite the hassle when I tried to diesel swap one.
From memory, it's all about tricking the cam position sensor and the crank position sensor. As long as those two are seeing a good signal, everything else should work (with a ton of warnings on the dash).
There are companies that can delete everything from the stock computer you don't care about (like gasoline injectors) to make all those warnings go away.

I thought a lot of people would have put this Cummins 2.8 into JKs by now and there would be a fairly known "process" to make it all work.

-Dan
 

superbuickguy

Explorer
So close.
intake, done
8VHZPIJh.jpg

exhaust
ZrT9tMBh.jpg

done
GhTQaXJh.jpg


what's left for me - put the interior back together.

then it goes back to Woodinville to a friend who loves wiring... he'll solve the ignition switch issue, wire the a/c pump and tie the temp sensors into the diesel sensor (thus enabling the fan circuit). finally wire the oil pressure switch and determine if we can fool the tach into taking the diesel outputs....

once it gets back, I'm doing a different 'house storage' system that integrates solar panels, and a lithium battery pack that also runs the engine-off a/c system.

this I'll publish later but the nutshell is we're using Zero Breeze a/c and their e-generator (batteries). I also think I can charge the reserve system with a simple 12v - 110v inverter. This should make the system easier and portable between our K9 rescue rigs.
 

superbuickguy

Explorer
Tricking the JK into thinking it has a "running" engine was quite the hassle when I tried to diesel swap one.
From memory, it's all about tricking the cam position sensor and the crank position sensor. As long as those two are seeing a good signal, everything else should work (with a ton of warnings on the dash).
There are companies that can delete everything from the stock computer you don't care about (like gasoline injectors) to make all those warnings go away.

I thought a lot of people would have put this Cummins 2.8 into JKs by now and there would be a fairly known "process" to make it all work.

-Dan
Interesting.... wonder if I've already eliminated those wires? love it when I make things harder. With that said, HP tuners is fantastic for turning sensors off (and their attendant dash lights). wonder what I can do about the signal it seeks with HP tuners.....

The other cool thing is I can change how the fan comes on (it's a solid state fan for those who don't know)... I'm hoping that I can fool the tach to work with the outputs from the r2.8. If not, a simple bracket a it should work just fine

*edit* it's the cam sensor that's the issue, not the crank position sensor, that's plugged in for that tach stuff....
 

Dan Grec

Expedition Leader
The other cool thing is I can change how the fan comes on (it's a solid state fan for those who don't know)... I'm hoping that I can fool the tach to work with the outputs from the r2.8. If not, a simple bracket a it should work just fine
Based on the interior your JK is a 2011 or newer. Is it a 2011 or 2012+
If it's a 2012+ it has a PWM main fan which is a very good thing. AEV will always upgrade to that fan when doing hemi swaps in the earlier JKs because it moves WAY more air and uses WAY less power.
You can power it from the TIPM if you want no problem with 100% factory wiring. I believe there is a company that can program the TIPM to change at what temp the fan will come on/off. I was in the middle of that when I gave up on my swap, but I know the next owner got it working flawlessly.

For the cam signal look what the 4bt guys do. They put a ring on the power steering pully usually and point the sensor at that. The signal doesn't have to be "accurate", it just has to see a signal and it will know it has a running engine, and make almost everything else work, including the tach.

Good luck, I'm sure you'll get there!

-Dan
 

superbuickguy

Explorer
well, now it's ready to go to the wizard...err... electrician
bolted the interior all back together.
NgNtFngh.jpg

when it gets back, I will have some house wiring (meaning, the stuff that doesn't run the vehicle) to resolve but it should be drivable
i6K4j3Mh.jpg
 

superbuickguy

Explorer
Based on the interior your JK is a 2011 or newer. Is it a 2011 or 2012+
If it's a 2012+ it has a PWM main fan which is a very good thing. AEV will always upgrade to that fan when doing hemi swaps in the earlier JKs because it moves WAY more air and uses WAY less power.
You can power it from the TIPM if you want no problem with 100% factory wiring. I believe there is a company that can program the TIPM to change at what temp the fan will come on/off. I was in the middle of that when I gave up on my swap, but I know the next owner got it working flawlessly.

For the cam signal look what the 4bt guys do. They put a ring on the power steering pully usually and point the sensor at that. The signal doesn't have to be "accurate", it just has to see a signal and it will know it has a running engine, and make almost everything else work, including the tach.

Good luck, I'm sure you'll get there!

-Dan
it's a 2014
My first attempt will be install the temp sensors in the r2.8 and hope they turn on the fan. If now, I'm using a PWM fan in my 76 Corvette - and love it - the only reason I don't just go straight to the aftermarket is the fan needs to come on with the a/c is engaged.... would rather just fool the Jeep stuff into working. One thing with that, I put an oscilloscope on the trigger wire for the fan and it is getting the baseline signal - so I might be able to piggyback an aftermarket controller with the stock system to get the best of both worlds.

the r.28 has a trigger ring on the crank pulley. wish I'd known about the cam sensor thing before - however, it's 4 sensors on this motor so a bit more cumbersome to rewire and put the sensors in place.... especially since I could just use a button (yeah, yeah, redneck but I'm already pro-jackstand so this isn't a far walk from where I'm already at).
 

Dan Grec

Expedition Leader
it's a 2014
My first attempt will be install the temp sensors in the r2.8 and hope they turn on the fan. If now, I'm using a PWM fan in my 76 Corvette - and love it - the only reason I don't just go straight to the aftermarket is the fan needs to come on with the a/c is engaged.... would rather just fool the Jeep stuff into working. One thing with that, I put an oscilloscope on the trigger wire for the fan and it is getting the baseline signal - so I might be able to piggyback an aftermarket controller with the stock system to get the best of both worlds.

the r.28 has a trigger ring on the crank pulley. wish I'd known about the cam sensor thing before - however, it's 4 sensors on this motor so a bit more cumbersome to rewire and put the sensors in place.... especially since I could just use a button (yeah, yeah, redneck but I'm already pro-jackstand so this isn't a far walk from where I'm already at).

I'm sure there's gotta be threads out there of people putting the R2.8 into the later JKs (that came with 3.6).
People must know the secret sauce to get basically all of the "Jeep" stuff to function as normal)

-Dan
 

superbuickguy

Explorer
sent the Jeep to one of my friends (who I'll shout out NuMark Automotive in Woodinville). He is the only mechanic I recommend. Not saying bad about others but he's one of the good guys.

and he gave me bad news. The starter is the first of the problems. Come on Cummins.... you can't build a starter?
 

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