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  1. #1
    Fuel Injected! JeepsAndGuns's Avatar
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    Hacking/tuning the jeep ecm

    So I have done some google work and constantly come up empty handed. My daily driver is a 93 jeep wrangler 4.0 straight 6. It has the factory sequencial multiport injection. With all the fun I have been having tuning the gm system I put in my cherokee, I would love to be able to tune the system in my wrangler. I know there would be much improvement with a mostly stock engine. But in the future I plan on building it into a stroker. For those who dont know about it. Its where you take the crank and rods from the older 258 straight 6 and put it in the 4.0 block and use the 4.0 pistions and you get around 4.6-4.7L out of it. Very popular thing to do with these engines. I plan on doing it once this one wears out. The normal thing people do is just swap for bigger injectors to compensate for the extra displacement. But I figure there is so much more that could be done because the engine is now pretty far from stock.

    The jeep ecm is a underhood weathertight one. I have a extra one and I pulled the cover off and can see through the plastic/gel stuff and see the board and what appears to be the EPROM. The gel seems easy to dig out. If I dig it out and desoder it, what are the chances I would be able to read it with my autoprom and the tunerpro prom I/O and save it to a file? Then, finding someone to write a tunerpro defination file for it?
    I'm thinking the ecm being weatherproof is the reason no one has tried to do this before. And I am not asking for someone to write a defination for free. I would be fully willing to pay for this. I would also need a datastream defination too. If these could be made, then I could simply soder in the moates adapter that allows remote mounting of the eeprom, and run a cable to under the dash and mount the eeprom there. Probably make a small box to put it in. I would then reseal the underhood ecm.
    The jeep system actually uses lots of real simmilar sensors and even a couple are GM (such as the map sensor, its the exact same one on the chevy tbi systems) It has a 3 wire tps, 4 wire iac, has a cts, iat, cam and crank sensors. I think if I could find someone smart enough and willing, it could be done. Looking at all the many many definations on tunerpros website, I dont see why it couldnt.

    What say yall.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  2. #2
    RIP EagleMark's Avatar
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    I think it would be easier to repin what you have to a GM weatherproof under hood ECM. Then tune it...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  3. #3
    Fuel Injected! JeepsAndGuns's Avatar
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    About the only gm ecm/pcm I think I would swap to, would be the 1220411. Its sequencial, has great aftermarket support, and can run a 6cyl. But its just so freaking expensive to tune. It would also require harness mods, and probably a couple diffrent sensors, and a crank trigger wheel/pickup fabed for it, cause the jeep one would not work. It would be really hard to hack up the factory untouched harness in my jeep (that I have had for a long time, and has always been my baby) If I modded the stock ecm, then thats the only thing modded. If it didnt work, or work out, I could just swap back to the original ecm and be done.

    So lets "pretend", for now, swapping to a diffrent ecm/pcm is not a option. I would like to keep the discussion on "is it possiable" I pulled the top cover back off the spare ecm I have, and looked through the gel with a flashlight, and its a 27c256 eprom in it, with the little picture of texas on it, also has a sticker covering the window and a bunch of numbers on it. There is a setting in the moates prom I/O for that chip. So I'm thinking it could be read? The jeep ecm's also have a 7 diget number on them, with the last 3 being twice the size of the first 4. The spare one I have is from a 93 cherokee automatic (my wrangler is a 93 5 speed) I had read the cherokee is supposed to have a "better" timing table. All I noticed was slightly less torque, so I swapped back to my original one.
    The first 4 digets are the same on both, so I would assume this would translate into a ecm service number (if we want to think of it like that) and the last 3 digets are whats diffrent. So I would assume thats gonna translate into a BCC or the tune on the chip.

    I just want to make sure, that beyond any reasonable doubt, that the jeep ecm is absoultely postatively not hackable/tuneable before I even start to think of swapping to a diffrent/gm pcm. I dont mind chip bruning, and I just LOVE emulation/real time tuning. And emulation is just so expensive to do with the 411.
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

  4. #4
    Fuel Injected!
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    I looked into this a couple years ago when I thought a mopar 5.2 or 5.9 swap might be good into my cherokee. I did not come up with anything except that you needed special hardware to program the PCM's and startup costs were in the $3000 range. So basically unless you were doing it on a shop level where the hardware and software would pay for itself its not DIY friendly. I did not find anyone disassembling the chips either...

  5. #5
    RIP EagleMark's Avatar
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    That's going to be a major project. Since it's such a popular vehicle if it were possable I think it would have been done. What are guys doing when they build an engine for that vehicle?

    There's an easier way to make changes to ECM for what's needed to tune the engine after you build it. PiggyBack tuners. They get wired into existing harness and make changes needed in signals to tune the new engine. I have used the Perfect Power products for vehicles such as yours with great results.
    http://www.perfectpower.com/index.ph...&id=5&Itemid=7

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  6. #6
    Fuel Injected! JeepsAndGuns's Avatar
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    I bet anything it has been done, but like said by cmaje72, its probably been on a shop level where they make/have lots of money and hire someone fulltime to do nothing but hack/tune the ecm.
    My guess why it hasnt been done on a wider scale is because it (appears to be) a eprom based ecm, not flash based. The eprom is sodered to the motherboard and then its all encased into the waterproof gel. Its not like the gm computers where you simply take two screws out and can uber easaly remove the chip, read, hack, tune, and reinstall it. I think thats why it has been done so much and easaly on the gm ecm's. And the ford the same way, so many out there, I'm sure the mustang builders pretty much demanded a way to tune the ford computers. So a way was found. The jeep ecm on the other hand is gonna take a little more work to get to the chip. I would have no problem doing this, I however am nowhere near smart enough to read the code and do all that magic to where it can be displayed in a tunerpro format where I can understand it.

    Anyone have a lead on any other forums I could join, or people to email to get in touch with someone smart enough to do said work?
    79 Jeep Cherokee, AMC 401, T-18 manual trans, hydroboost, 16197427 MPFI system---the toy

    93 Jeep YJ Wrangler, 4.0L, 5 speed, 8.8 rear, homebrew hub conversion and big brakes, hydroboost, 2.5in OME lift, 31x10.50's---the daily driver

    99 Jeep WJ Grand Cherokee limited, 4.0L, auto, 2wd, leather and power everything, 99% stock---the long distance highway ride.

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