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Do I need my ECU, 90 YJ

Discussion in 'Wrangler YJ (1986-1995)' started by JTHM71, Mar 31, 2017.

  1. Mar 31, 2017 at 8:17 AM
    #1
    JTHM71

    JTHM71 [OP] Active Member

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    Izaak
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    1990 YJ SAHARA
    I have some
    I have a 90 YJ with a 4.2. I have replaced my original carter carb w/ new Weber. I am currently replacing my conglomeration ignition system with an updated HEI system which has allowed me to remove ALOT of wiring ,from plugs and connectors that went away with the carb swap and now with all the ignition system. Looking at the wiring that is left I wonder how much I REALLY need going to the ECU or if I even need the ECU as all my actual emmissions system short of the CAT has been removed. O2 sensors ,a few other random sending units and that whole cluster beside the battery holder look to me to be kind of pointless, BUT i know I get a bit rambunctious sometimes when I start trying to simplify things by cutting things out, so I figured I'd put it out here for the educated and experienced masses to give me some feedback.
     
  2. Apr 3, 2017 at 9:29 AM
    #2
    Dbarlow

    Dbarlow Member

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    I have an 89 and am wondering the same thing. I have what they call a "nutter bypass" but the ecu is still there. I'm wondering if this bypass renders the ecu obsolete now or does it still have to be in the wiring loop?
     
  3. Apr 3, 2017 at 11:15 AM
    #3
    JTHM71

    JTHM71 [OP] Active Member

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    I have some
    I must say I'm pretty astounded that this thread has not recieved ANY feedback..... this cant be the first time this issue has been raised ......
     
  4. Apr 3, 2017 at 11:19 AM
    #4
    JTHM71

    JTHM71 [OP] Active Member

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    I also had done the NUTTER BYPASS,,or so i thought ,,and the jeep would not run at all, so I UN DID it....during this upgrade i realized I had actually sliced the wrong purple and orange wires,,,,i had cut in to the purple for the temp sensor and the orange for some other random something , but Im pretty certain that with removing the entire ignition system that the NUTTER BYPASS is completely out of the loop
     
  5. Apr 3, 2017 at 11:45 AM
    #5
    OFFGRID

    OFFGRID Well-Known Member

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    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    The nutter bypass does bypass the ECU for engine control. If you have junked the Ford electronics and gone HEI, then you pretty much are there, depending on how you wired the HEI distributor.
     
  6. Apr 3, 2017 at 11:55 AM
    #6
    OFFGRID

    OFFGRID Well-Known Member

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    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
  7. Apr 4, 2017 at 4:36 PM
    #7
    JTHM71

    JTHM71 [OP] Active Member

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    I have some
    So OFF , you linked me back to my other thread hahahahah, so you think i can pretty much remove the ECM at this point and just disconnect all the rest of the random sensors left over from the emmissions system? O2 , and what ever the rest of these damned things are.
     
  8. Apr 4, 2017 at 8:56 PM
    #8
    OFFGRID

    OFFGRID Well-Known Member

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    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Ive never done it on a 90 YJ but theory is you've direct wired the HEI. Bypassed all ignition. Your carbureted not fuel injected. No real need for O2 sensors. The temp sensor was only to bypass the ecm until the jeep gets to running temp at which point the ecm takes control. Try disconnecting the ecm and start it.
     
  9. Apr 9, 2017 at 7:19 AM
    #9
    JTHM71

    JTHM71 [OP] Active Member

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    I have some
    So the answer to the question is NO i do not need my ECM . IT HAS BEEN COMPLETELY REMOVED , as well as all the witing and even the 2 diagnostic harnesses that ride on the side of the battery tray. I did a complete trace of all wires from those hatnesses and relays and the CHIP, labled them and snipped them where aooropriate to un tangle them from the loom and away they went.
    The ECM I removed from the harness and then pulled the harness through the fire wall and away it went.
    This reduced my wiring loom by 1/2 at least.
    I will be removing all the random sensors from the intake manifold and plugging them.
    As it stands the 2 relays and the CHIP neside the battery are still in place ,But with only a couple wires connected,
    Over all i am very pleased with the outcome and simplifying of the electrical system.
    Obviously you cant do this if you need to pass emmissions BUT, i cant anyway. In PHX my non stock carburator voids my emmissions eligibility, even though it passes the ACTUAL smog test.
    Good luck to anyone who decides to go this route. It was easier than expected.
     
  10. Apr 9, 2017 at 1:27 PM
    #10
    OFFGRID

    OFFGRID Well-Known Member

    Joined:
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    Messages:
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    Gender:
    Male
    First Name:
    Peter
    Houston
    Vehicle:
    1979 Jeep CJ7, 258, TH350, NP208
    Howell fuel injection, header, HEI distributor, TH350, NP208, SOA lift with YJ springs in the front & GW springs in the Rear. AMC20 with G2 1 piece chromos trussed, Dana 30 with G2 chromos and 760x ujoints and MM Stainless Hubs, Geared 4.56. Tom Woods shafts, Metal cloaks, Caged, 37" Toyo MTs.
    Luckily in Texas if a car is at least 24 years old it only has to pass a safety test.
     

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