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Thread: Hacking/tuning the jeep ecm

  1. #61
    Fuel Injected! JeepsAndGuns's Avatar
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    I have pretty much all but given up on the stock Jeep ECM. Its a great ecu, tough and durable, but as far as tuning support, there pretty much none. An those who can do it, will not share. This thread acted like it was gonna take off and go somewhere, but ended up smashing into a brick wall.

    I have decided to instead, to convert it over to a GM 1227727 ECM. A few little mods to the engine (dist. and alt.), and hooking up the harness and I should be in business. There is way more tuning support for GM ECM's.
    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. #62
    Carb and Points!
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    Quote Originally Posted by JeepsAndGuns View Post
    I have pretty much all but given up on the stock Jeep ECM. Its a great ecu, tough and durable, but as far as tuning support, there pretty much none. An those who can do it, will not share. This thread acted like it was gonna take off and go somewhere, but ended up smashing into a brick wall.

    I have decided to instead, to convert it over to a GM 1227727 ECM. A few little mods to the engine (dist. and alt.), and hooking up the harness and I should be in business. There is way more tuning support for GM ECM's.
    I know this thread has been dead for 5 years, but for those interested.

    There's actually been a concerted effort to tune the sbec-2 for jeeps over on turbo-mopar.com. While my knowledge is limited on engine management, Ive been giving a few of the guys over there a hand with testing/figuring out some of this stuff.

    Turns out the SBEC-II in jeep is similar, though not identical to the SBEC's used in turbo chryslers and others. There's been some good progress on reverse engineering the code and finding 3d tables/parameters for OBD-1 jeeps. There exists a suite of tools called MPTune and MPScan that are written by one of the very talented guys on Turbo-Mopar that allow for datalogging and tuning of these old chrysler ECUs. The effort that was mounted was to figure out the tables for the Jeep ECUs in order to utilize MPTune to be able to write new calibrations.


    Separate form this effort, I actually purchased a tune from Chris Jensen, who is known for tuning SBEC/JTEC based Vipers and such. He also does jeeps and did end up street tuning my OBD-1 jeep. Though we agreed that any effort on turbo-mopar would be separate from the tune he provided me. Aka, We made a gentlemen's agreement him I would keep the tune he sold me away from the internet and I respect that. I only bring it up to mention it is possible and has been done before by professionals.

    The cool thing with these SBEC-IIs are theyre pretty cheap, plentiful and interchangeable. The later ones are flashable, but the earlier ones need to be socketed. Socketing them is pretty easy if you know how to solder and are patient. I was able to put a socket on a spare SBEC-II I had in order to have Chris tune it for me. My experience with Jeep SBEC's are they have a built in Latch chip so just a regular run of the mill 27sf256 chip will work in the socket.

    I can say Chris's tune provided my stockish 4.0 with a very noticeable gain in power and drivability! So there is definitely room for improvement on the table. He did tell me that in his experience, Chrysler seemed to put a huge margin of error for timing on 4.0s and there definitely is room for improvement.

    Here's the thread this stuff was happening on, it's sort of slowed down but I think there's still interest:

    http://www.turbo-mopar.com/forums/sh...herokee-Tuning
    http://www.turbo-mopar.com/forums/sh...hing-Questions
    http://www.turbo-mopar.com/forums/sh...ep-SBEC-tuning
    Last edited by sev; 08-13-2017 at 04:13 PM.

  3. #63
    Carb and Points!
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    Quote Originally Posted by rts91tsi View Post
    I am curious which microprocessor your ECU has. I have been searching around via Google and found that some of the SBECs used the exact same Motorola processor that the DSMs use, for which there is documentation available.
    SBEC-IIs used in the jeep are 68HC11s

    ( I know.. 7 years later...)

  4. #64
    Fuel Injected! JeepsAndGuns's Avatar
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    Very interesting. If someone makes a complete XDF (or whatever it is called in their program) for the jeep 4.0 cal, I would be very interested. I have yet to convert mine over the the GM ecm (life has been getting in the way)
    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.

  5. #65
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    Quote Originally Posted by JeepsAndGuns View Post
    Very interesting. If someone makes a complete XDF (or whatever it is called in their program) for the jeep 4.0 cal, I would be very interested. I have yet to convert mine over the the GM ecm (life has been getting in the way)
    JG, working on piggybacking the JTEC in my Ram with a 7727. About 2/3 complete. Maybe ill share once its running, hopefully.
    '86 Grand National

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