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2005 LJR R2.8 build


DieselJeep

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Oct 31, 2018
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820
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KY
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 .?
To be clear, I went with aftermarket gauges, so I don't have the experience, but I did use a Dakota Digital DSL-1 to get the right tach on my new gauge set. Not sure if this would do it for you all that kept the OEM gauges coming from the PCM.
 

coastalcop

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Aug 26, 2019
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Third Coast
I should add that I am relatively new to jeeps and have never owned a diesel. I just noted that you were discussing different squarewave requirements. I have used a scissor jack to fix dents in a Lancia, and repurposed tools in other ways, so it seemed possible ymmv 😎
 

DieselJeep

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I think these signals are all mostly squarewave, as it's just a pulse per revolution, but the computer assumes you've got a 6 cylinder with an electrical ignition system, so it's gonna see a different amount of tones than just something simply from a flywheel. My assumption with most engines especially the Cummins, which is setup for multiple applications probably takes a signal from a camshaft or something. Diesel is compression ignition (CI), so they obviously can't get an ignition signal easily.

There are some trying to keep the OEM gauges and remove the PCM and that gets a bit more complicated because now you're trying to drive the needle motors and stuff. I have heard of this being done, which I think it kinda cool, but you've already got a handy little box ie the PCM, so it's only a slight convenience so you can more easily relocate the box vs the PCM.

I'm planning for dual starting/winch batteries and the PCM takes up some space where one of the dual batteries goes.
 

NDSpeed

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Fairbanks, AK
Having dived as deeply into the wiring harness as I did. I wonder how much harder it would be to relocate the PCM. It does take up a lot of real estate.

I would want new multi pin connectors because I really dislike working with old connectors. Not impossible. Just annoying.
 

DieselJeep

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Oct 31, 2018
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Having dived as deeply into the wiring harness as I did. I wonder how much harder it would be to relocate the PCM. It does take up a lot of real estate.

I would want new multi pin connectors because I really dislike working with old connectors. Not impossible. Just annoying.
I thought about that too, but the amount of wiring scared me. I saw a forum with a guy doing an LS swap into some vehicle and he pulled all his wiring and laid it out on like plywood and made new harnesses and everything based on where stuff would go and proper lengths and he may even used to proper wiring color, which that's a lot of spools of wire.

While I strive to do that nice of work, in reality I want to get out and use my Jeep too much. Especially where I was in the build and wanting to get my Jeep on the road after being without it for months. Maybe when I pull my EGR, maybe I'll get back into that area and tidy it up more especially since I'll have more room to route the wiring.

In any case I've got so many electrical items to add to my list and keeping those organized is going to be a task in itself. I've been looking at the Bantam SPOD HD stuff, but it's expensive and I would rather get my gear ratio changed and add lockers and get an Atlas installed.
 

NDSpeed

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Jul 11, 2019
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Fairbanks, AK
Six years of just looking at my Jeep. At one point I left it for two years in IN while I made the move to AK.

While I was going into the Hemi swap I pulled the entire harness out of a Grand Cherokee.

I purchased a peg board from Lowe’s and zip ties the whole harness on there to make it easier to manipulate and not have a mess of A rats nest of wiring.

the TJ harness was small enough I could manage it on my work table.
 

DieselJeep

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KY
I'm pretty sure you could hide your PCM behind the dash and then save you on some real estate. I'm a little worried about battery size for a diesel. I really like multiple batteries for starting and for winching. I think a couple AGM dual purpose batteries would do the trick nicely. The Rural King AGMs are like $135 ea.
 

NDSpeed

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Ugh the damn insanity. Took the wire harness out to finish it up. Install sleeves. Looks beautiful. Installed it and. Bam. no Bus
 
OP
1945GPW

1945GPW

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Mar 12, 2018
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@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:

Hey thanks for the reminder, forgot about that. I'll go grab a quick video starting it up.
 

NDSpeed

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Jul 11, 2019
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Fairbanks, AK
Status update. This thing is a blast to drive. Even though I’m only in front wheel drive mode while I wait for the rear drive shaft. Makes the snow a bit more challenging.

did you remove your evap system. I’m thinking spot dropping the fuel tank again and installing on board air back there
 

DieselJeep

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That's great news that you're able to drive it now.

My tank setup is different, but there was some evap type stuff on mine and I did remove mine since diesel isn't as volatile as gasoline. You do need some simple valving, so you don't contaminate your tank, nor cause a vacuum as you drive. I completely plugged mine off for awhile before I had a vent valve (just a basic one used for diffs) and it never gave me trouble, but when I'd open my fuel cap, you could hear air rush.

Are you going to put an air compressor back there? Will you have good access for airing up tires? I've got to add air so please post some pics when you get a chance. I recently added air to my truck, but it's got an obscene amount of room, being a quad cab long bed model.
 

NDSpeed

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Jul 11, 2019
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Fairbanks, AK
I‘ve got to pull the fuel tank to continue drilling out the upper shock mount bolts. When I do I’ll be looking into the evap container area. I remember reading years ago it was an area big enough to install a subwoofer. I’m sure that whole well behind the passenger tire is empty other than that canister