2005 LJR R2.8 build

Post a picture of the axis supplied battery cables and I can number the ends and tell you where they go. The one off the ALT goes to the starter. Also I kept my PCM to keep it simple and keep the factory gauges. I used the original yellow ignition wire that started the 4.0 engine, and plugged that directly into NO1 on the cummins starter.
 
The thick bundle goes from the battery and fuse block to the grid heater and starter.

Alternator to the battery.

image.jpg
 
So I jumped the starter. It turned over but never started. So I’ve taken all the wiring back out to start over. I didn’t like the rats nest of a mess it made on top anyway. But now at least I can lower the radiator hoses since they were on top too.

And the Murphy gauge gave me a new code. So I’m up to three codes now. Grid heater was wires with the fused wire.

I’ll figure this out.
 
Oh man! I've been obsessing over this r2.8 engine! I want one for the jeep and one for the civic!! Lol
If I had the resources and know how, I would swap out the engine in the jeep in a heart beat!!
 
  • Like
Reactions: BugoutJeep
Oh man! I've been obsessing over this r2.8 engine! I want one for the jeep and one for the civic!! Lol
If I had the resources and know how, I would swap out the engine in the jeep in a heart beat!!
You can also pay companies to do the swap for you, but it's not cheap.

I'm really liking the kit where they mate the R2.8 to I think a TR-4050. I think I'd really like that gearing, but the AX-15 would be fine. I just wish the AX-15 had more of a granny gear.
 
  • Like
Reactions: GorillaBiscuit
Agreed. Lot less headache. I took my Jeep apart 6 years ago to do a hemi swap. Now there is a diesel in there and I am struggling with the wiring.

I haves played with wiring in 15 years. Now it’s all that stands between me and driving the Jeep again.
 
  • Like
Reactions: BugoutJeep
I got really worried at first about the wiring, but it ended up being pretty straightforward to get it running.

Brake lights, gauges, that's a bit harder, but not terrible. TJs were still relatively simple. I still have a fist full of wires I should remove, just to reduce clutter and I already removed a bunch.
 
Finally got it started. Granted. I cheated. But I was stumped as to why it wouldn’t start. Turns out I had the fuel lines swapped. So no matter how many times I pumped the fuel filter. It never primed.
 
  • Like
Reactions: BugoutJeep
Alright guys, here is an update on the 2005 LJR R2.8. Unfortunately I couldn't get ahold of Kevin (Axis) since the end of August which was very frustrating. He finally started emailing back and forth about a week ago, anyway he sent me the larger fan but because my radiator didn't have a temp port built in I had to cut the upper radiator hose and attach an adapter for the temp sensor to screw into. Also the temp sensor he sent turns on at 185 and off at 165 so way to cool for this set up and the manufacture stopped making the ones that turn on at 205 so ended up having to wire in a couple relays to get the fan to come on with the cummins signal and for the AC request.. Long story short its all hooked up and seems to do a lot better keeping the coolant temps down. The weather is cooling off here in Colorado so I'm sure that's helping as well but its defiantly keeping the temps lower than with the old fan... We hooked up the camper trailer and did a pull test up a grade we did before with it. Old fan we had to slow down to around 35 mpr in 4th gear and temps were 223 and climbing. New fan we were cruising about 55 in 6th gear with temps not getting over 203.. Without the trailer it stays much cooler than before as well.. Although it was very frustrating having to wire in this new fan it seems to have done the job..

Also for you guys wondering about the power, lets just say pulling the camper up a steep grade it accelerates better than my stock jeep empty and with a tail wind. Power and fuel mileage is simply amazing.

394284A0-E144-4E3C-A642-4279D93C6B46.jpeg
 
Last edited:
Update for me as well. Finally cranked it off of the key. Had to put in a new crankshaft position sensor for switching over to the 6Spd. Now to put it on hold for the next month. The I’m gonna rebuild the layout of the wiring harness sense nothing is hooked up from the transmission back.
 
I also completed the AC plumbing and wiring this week. It’s very tight in the engine bay now and it will be a huge pain in the ass if something needs repaired or replaced but hoping that won’t be for a long time.

730649EB-AE4F-4B69-BAC0-2378806AC824.jpeg



C6A75B45-D61B-41FF-95F6-8DDE20CFB733.jpeg


F2B55FB1-9587-43D8-85EC-67A921A2405B.jpeg


D4D153DA-C67F-4750-8C58-1907B3E79DCD.jpeg


5FDE6B32-4D0F-47E5-AA50-9668AF4D5643.jpeg
 
  • Like
Reactions: TJ Starting
Thank you guys for all the help. I was able to find the full schematics on the internet and realized I had an open sensor in the CAN bus line that was blocking confusing the network. Wired in a new sensor and have finally started Nugget via the Key.


Now over the winter months I’ll get to the fan and the Cam sensor so I have a tach.
 
Just FYI, I stole the following from a very reputable Cummins source and this was specifically for a XJ build, but....


"For what it's worth, the way we wired our black TJ was to keep the stock PCM and use the Cummins tachometer signal wire connected to the jeep's cam position signal. This is the signal that excited the PCM to think there is a running 4.0L in it. From there, the factory dash is reading engine speed from Crank Position Sensor on bellhousing and driving the dash tach with that.

If you're not running the 4L flywheel, then you may need to make a tone ring to mimic the tooth count and put it on the front of the Cummins crank and mount the 4L crank position sender to that for your dash tach. I'm guessing you could also splice the Cummins tach signal to both give input into the cam sensor and crank sensor but from what I'm reading you may need an interface for as the 4L crank may be looking for 3 pulses per rev whereas the 2.5L jeep engine looks for 4... Not sure if the 4Cyl PCM is plug and play with your Jeep's harness...

From our manual:

"If the user chooses to integrate the factory tachometer, the R2.8 CM2220 R101B wiring harness includes a tachometer output signal wire. The signal wire (white wire, labeled Tach, pin 9) exists in one of two states, source or sink. The ECM toggles the state rapidly to produce a square wave with a variable frequency and a fixed nominal duty cycle of 50 percent. Four pulses are produced for each crankshaft revolution, for an output frequency (Hz), per the following formula: • Engine rpm x 4 pulses per revolution x 1 minute per 60 seconds

There is a minimum allowable frequency for the square-wave, which corresponds to a lower threshold of the engine speed which can be reported to the tachometer. The ECM provides a single pin output interface for the tachometer output with the following requirements in the table below. Item Requirement Operational States Two: SOURCE and SINK Modes One: pulse width modulation (PWM) Minimum Source Voltage (@Maximum Source Current) 6.0 volts

Item Requirement Maximum Source Current 5 mA Minimum Load Resistance 1100 ohms Maximum Sink Voltage (@Maximum Sink Current) 0.5 volts Maximum Sink Current 5Ma Frequency Range 2-8500Hz" "
 
@1945GPW congrats on a great build. I just read this whole thread this morning. Very entertaining. Did you ever post a video with sound with your new exhaust? I would love to hear it. By the way, I loved the scenery where you live.

Now I just have to wait for my 4.0 to die:ROFLMAO:
 
  • Like
Reactions: BugoutJeep
@1945GPW congrats on a great build. I just read this whole thread this morning. Very entertaining. Did you ever post a video with sound with your new exhaust? I would love to hear it. By the way, I loved the scenery where you live.

Now I just have to wait for my 4.0 to die:ROFLMAO:
Good plan. By the time the 4.0 dies, if you start saving now you'll have enough for your dream build. I'm really liking the offering from Farmstrong on the R2.8 mated to a TR-4050. I think that's a really interesting combo.
 
  • Like
Reactions: AussieNick
Just FYI, I stole the following from a very reputable Cummins source and this was specifically for a XJ build, but....


"For what it's worth, the way we wired our black TJ was to keep the stock PCM and use the Cummins tachometer signal wire connected to the jeep's cam position signal. This is the signal that excited the PCM to think there is a running 4.0L in it. From there, the factory dash is reading engine speed from Crank Position Sensor on bellhousing and driving the dash tach with that.

If you're not running the 4L flywheel, then you may need to make a tone ring to mimic the tooth count and put it on the front of the Cummins crank and mount the 4L crank position sender to that for your dash tach. I'm guessing you could also splice the Cummins tach signal to both give input into the cam sensor and crank sensor but from what I'm reading you may need an interface for as the 4L crank may be looking for 3 pulses per rev whereas the 2.5L jeep engine looks for 4... Not sure if the 4Cyl PCM is plug and play with your Jeep's harness...

From our manual:

"If the user chooses to integrate the factory tachometer, the R2.8 CM2220 R101B wiring harness includes a tachometer output signal wire. The signal wire (white wire, labeled Tach, pin 9) exists in one of two states, source or sink. The ECM toggles the state rapidly to produce a square wave with a variable frequency and a fixed nominal duty cycle of 50 percent. Four pulses are produced for each crankshaft revolution, for an output frequency (Hz), per the following formula: • Engine rpm x 4 pulses per revolution x 1 minute per 60 seconds

There is a minimum allowable frequency for the square-wave, which corresponds to a lower threshold of the engine speed which can be reported to the tachometer. The ECM provides a single pin output interface for the tachometer output with the following requirements in the table below. Item Requirement Operational States Two: SOURCE and SINK Modes One: pulse width modulation (PWM) Minimum Source Voltage (@Maximum Source Current) 6.0 volts

Item Requirement Maximum Source Current 5 mA Minimum Load Resistance 1100 ohms Maximum Sink Voltage (@Maximum Sink Current) 0.5 volts Maximum Sink Current 5Ma Frequency Range 2-8500Hz" "

Seeing as a Speedo healer or yellow box does nothing but change the input squarewave frequency , might that also be used to change your pulse rate to give the pcm what it wants .?