banjobill80 Posted January 18, 2016 Share Posted January 18, 2016 hi all hopeing for some ideas here . so I'm knee deep in my 4.0L swap into my 86 mj i got a runing 88 donar with the 4.0 have it bolted in to my 86 i used wire harness, dash,steering colume and all the fixings from the 88 so i thought it would be a pretty easy switch and so far all has went fairly well have the motor all bolted up have not begun vacume or coolant exc but thought i would like to hear her fire she cranks over and have power to the coil but no spark replaced cap button plugs and wirers still no spark. as i said she ran in the donar truck so ecm and all that should be fine. fuzable links and everything seem fine any thoughts would be appreciated Link to comment Share on other sites More sharing options...
Eagle Posted January 18, 2016 Share Posted January 18, 2016 Did the crank position sensor (CPS) get damaged or disturbed during the swap? Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 18, 2016 Share Posted January 18, 2016 As Eagle said your CPS! Have you installed the tranny yet with the cps bolted on? CPS needed for ECU to let it fire. Before you put cps on, do the mode, to get the advanced timing for better mpg on highway! Link to comment Share on other sites More sharing options...
banjobill80 Posted January 19, 2016 Author Share Posted January 19, 2016 ok it must be the cps i had a problem with the wireharness where the previous owner had cut some relays out of it so i found a comanche in a bone yard had the 4L with auto trans everything seemed to plug in except there was no plug for the cps and not knowing what the cps was for thought it would be a bridge i would cross later. guess i will have to reinstall the old harness and deal with the relay problem after all. so now i wonder what the harness was out of that i got at the bone yard everything has a spot but the cps Link to comment Share on other sites More sharing options...
cruiser54 Posted January 19, 2016 Share Posted January 19, 2016 ok it must be the cps i had a problem with the wireharness where the previous owner had cut some relays out of it so i found a comanche in a bone yard had the 4L with auto trans everything seemed to plug in except there was no plug for the cps and not knowing what the cps was for thought it would be a bridge i would cross later. guess i will have to reinstall the old harness and deal with the relay problem after all. so now i wonder what the harness was out of that i got at the bone yard everything has a spot but the cps Test it!! Tip 7. Link to comment Share on other sites More sharing options...
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