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1997 Jeep Cherokee

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  • 1997 Jeep Cherokee

    Here we go! Started back in October when the old 4.0 threw a crank bearing and had to be scrapped. I decided to repaint and ended up doing all the bodywork myself before dropping the new R2.8 in. After 10 or so months of weekend tinkering and after work head-scratching it's finally back on the road! I love the power and the noise. I got a custom exhaust put on it yesterday and it sounds mean! Last challenges include getting my stock gauges to work (currently devising a small circuit board to integrate old and new sensor signals and send them along to the gauge cluster via the CCD Bus protocol) and dealing with intake air temps getting too high on big hill climbs. I'm told I may need a bigger intercooler which doesn't thrill me but lessons are extra I guess. Any questions, ask away!

  • #2
    I’m sure I will have a lot of questions soon enough- but congratulations!

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    • #3
      I must have missed your build. It looks great. I like the idea of integrating the J1939 and your stock sensors, but I wonder how much it will ultimately cost, unless you're really good with this kind of stuff.

      From my build I like that I went with aftermarket gauges that are independent (it gives me peace of mind to check my reading between independent sensors). I like having a GPS speedometer as well for a few reasons.

      What other specs do you have for your build? I'm especially curious on gearing, since I'm not geared how I want to be at the moment and honestly I'm kind of wishing I had gone with a different transmission.

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      • #4
        Thanks yeah I only put this up a couple weeks ago. Need to fill in a lot of details. I'm still running my stock axles with a Chrysler 8.25" rear and 3.73 gearing. It's about to go though as I can hear the ring gear rattling especially on hard turns. My plan is to do a Ford 8.8 rear axle swap. I've got an AX-15 transmission that I had rebuilt locally. I used Quickdraw Brand's bellhousing and modified cummins flywheel with jeep clutch and pressure plate and LOVE it. The clutch engages right in the middle of the pedal throw and has great feel. It's a LUK, nothing fancy. I had to get a short-throw shifter since I had to slide the whole drivetrain forward as far as possible to get the engine to fit. Even so, I had to do a bit of panel-beating around the bottom of the trans tunnel and fold the pinch weld seam that runs around the top-back of the engine bay to get the engine in. Not terrible, just tedious.

        As for gauges, I have a friend who works in the industry as a software developer and he's been helping me along. Still, it's proving to be quite a challenge and I may opt for aftermarket everything. I just really like the look of the stock gauge cluster and think it would be really cool to keep is sleeper-ish.

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        • #5
          That sounds like a great setup. I wish the cost was lower so I could build more of these.

          I really wish I could have slid my setup forward more so I could try and fit a doubler tcase. I have a YJ that's been wrecked and the thought of doing another diesel swap is very high on my list, but dropping $15k+ into it is a hard bargain at the moment and honestly my build ideas are probably closer to $30k. But it was a 4 cylinder Jeep with AX-5 and I think the 4 cylinder is toast now and anything I'd want to do the AX-5 couldn't handle, so I'm kinda stuck looking at cheaper used engines.

          Yeah I've got a buddy that's good with electronics and stuff and he mentioned building a converter box, but I guess honestly if you've already got a PCM, just relocate it. Originally my plan was to get it running with the PCM, then relocate the PCM. Then I started wanting a very different look and wanted to integrate like a tablet into the dash, but I wasn't sure what I'd even be able to read and the stuff I started to look at was creep into the $2k+ range and I settled back down to Earth and found a couple setups I liked and then let the wife decide. My dash still isn't fully integrated. For some reason the "wait to start" doesn't appear and my lights won't dim right. The wiring diagram I have isn't correct so I'm just into testing each wire honestly it just hasn't been a big deal to me.

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          • #6
            Farmstrong Inc. is partnered up with Quickdraw Brand and they're offering the crate engine, bellhousing, engine mounts and Tremec TR-4050 6-speed for $11k right now. Seems like a good deal and I believe they make YJ mounts. Might be worth scoping out if that's your dream build. I saw the deal on their Instagram page but can't find it on their website so you may have to call.

            My original plan was to keep my PCM and run sensors to it to get the gauges working but I've gone through all the wiring diagrams and right now it appears to be dead. So many things are unhooked though that I don't know if it's just not turning itself on or if I fried it somehow. If I could find another one to swap in and try I would but I hate to spend $200 on a new one to find out it's just not coming on due to no crank signal or something. Still, it doesn't seem to be sending any error codes and won't even show fuel level even though it's all hooked up and doesn't need a signal from the engine for that gauge to work which is why I'm thinking it may just be toast. Maybe I'll look around on Ebay...

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            • #7
              Yeah I saw that combination from Farmstrong and it looks awesome, but even at $11k I'm still not going to have everything finished for probably much under $20k, because I'd probably convert it into a truck. Plus I've already got a TJ with R2.8 in it and it's just hard to justify 2 builds like that.

              I've heard you have to "excite" the PCM to get it to turn on. I believe this is done from some of the ignition wires. I remember some guys doing this on Jeep TJs. I assume it's very similar.

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              • #8
                Yeah I'm probably in for $20k at this point including repainting supplies and a new bumper up front. If I actually accounted for my time spent I'd have been better off building a small house!

                Thanks for the info about the stock PCM. After thinking about it a bunch, I think you're right. I just need to get my stock PCM to "wake up" and do its job. I did a little more internet research and it sounds like the pcm clicks on only if it sees a signal from the crank sensor (not necessarily that the engine is turning over, just that the sensor is connected). Mine currently is not and I'll rectify that this weekend and post an update. If it works I'll be jumping for joy.

                I also noticed that the Cummins crank position sensor runs off of the crank pulley which has notches cut in it. It's a long shot but I'm going to try affixing the jeep crank sensor near that pulley and see if I get a tach signal. I'm more curious than anything and realize it probably won't work but if it did, all of my stock gauges would be working and it would have cost me nothing in new parts.

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                • #9
                  There's a website for TJs and a few guys have gotten this to work. I would imagine the Jeep sensor would be looking for a different pulse, to accurately display your RPMs. You may be able to use a converter or something.

                  https://wranglertjforum.com/threads/...8-build.21092/

                  I think he used stock gauges. If not check a few more R2.8 builds.If you do get it working, please leave a detailed post about it, because this is an issue for a lot of us.

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                  • #10
                    Well I tried hooking up cam position sensor and crank sensor today and still no action from the gauges. I reached out to a friend on the NAXJA forum who's good with electronics and is actually in the midst of a TDI swap himself. Maybe he'll have some thoughts. Here's where I'm at:

                    I'm leaning toward keeping my stock PCM (engine computer) to run gauges after a lot of thought. I'm hoping it'll mean no A/C wiring changes too as the compressor clutch is activated via the PCM.. Unfortunately I can't get any action from the needles or the A/C at the moment. The cluster passes all the self diagnostic tests, the odometer reads the mileage but isn't counting up anymore and the dummy lights all work so I think the gauges themselves are fine.

                    What I need to figure out now is what sensors are necessary for the ccd bus to start communicating with the gauge cluster. I tried hooking up an OBD scanner to the diagnostic port but it wouldn't connect so I assume there's nothing being sent out by the computer at all. I read that the cam position sensor has to be hooked up to excite the pcm but I tried that and it didn't help. My fuel gauge and speedo should be functional and the pcm has battery power, ground and the start/run 12v wire from the key all hooked up and connected well. I also tried hooking my crank position sensor back up but still no dice.

                    The pcm gets warm so something is going on but I don't know what. I get 2.41 volts from the ccd+ and CCD- wires. Do I just have a bad PCM?? I hate to drop $200 on a new one and find out it's some circuit that needs to be hooked up and that my old one was fine. Thanks in advance for any thoughts on this!

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                    • #11
                      Personally I'd be leaning toward a bad PCM, but I suck at electrical stuff. Especially when I don't quite know how it's supposed to work.

                      Since it's running, I would probably lean toward either getting the PCM diagnosed, or just continue scouring the internet to figure out if you missed something.

                      Good luck.

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                      • #12
                        I'm leaning that way as well. I went through everything again this weekend and everything except the pcm itself is working like it should. Luckily I've got a friend with a 98' XJ who's going to stop by this afternoon and we're going to try putting my pcm into his rig and see if it drives his gauges. I'm really hoping it doesn't!

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                        • #13
                          Well the verdict is in; my PCM is bricked. It did the same thing to my buddy's XJ as it was doing to mine - no gauge needle movement and when I tried cranking his engine to get a crank and cam signal it didn't wake anything up. I'm currently talking to a friend on the NAXJA forum who just finished a TDI swap and built a circuit board to run his Jeep gauges using Jeep sensors so I'm hoping he can build me one or explain the process. My other option is to buy a remanufactured Jeep PCM but they aren't very reliable from what I'm reading and bypassing it might be a good solution if I can get a processor to run the Jeep CCD protocol which communicates with my stock gauges.

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                          • #14
                            Keep us posted as I've always wanted to do a TDI swap and Kubota swap, oh and more Cummins swaps....

                            I would probably go with the circuit board and then look for a very cheap used unit as a backup.

                            Recently I was having such a frustrating gremlin that I was hoping to find a cracked head on my tractor. I pulled the head and nothing. Engine looked brand new. Everything I could check without getting really into the block was within spec. Got it back together and talked to a local tractor shop that works on old tractors and came away with a $4 plate that seems to have fixed that gremlin, but now I'm having a new fuel/spark gremlin to hunt down. It never ends.

                            Sounds like you're well on your way.

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                            • #15
                              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"

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