no spark, need advanced help

  • zlover23
    zlover23
    Senior Member
    • 291

    no spark, need advanced help

    Hey guys I'm having a no spark issue with my z. Ran codes and got code 21. replaced the coil, power transistor, distributor/CAS, tried different ecu, rewired prw2 mod, checked all visible ignition wiring (haven't gone searching through the lumes yet). Also completely disconnected the theft system as I thought that could be causing issues and to just eliminate a variable but still no spark!! Getting 12 v to the coil. What else can I check or what have I missed? What would be the next step? ECU pin out? If so, can someone please post a link to a how to or an ecu diagram regarding the ignition system, I have searched but no luck. Thanks a lot in advance, really trying to get this thing back on the road soon!

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"
  • pokeyquick
    pokeyquick
    Member
    • 44

    #2
    Check ignition relay, on driver side kick panel, 3rd relay.
  • zlover23
    zlover23
    Senior Member
    • 291

    #3
    thanks for the response, checked it and the ignition relay is working ok. I went and worked on it some more today and performed a few more tests:
    - ECU pin out test for CAS per fsm: continuity exists and 0 resistance in circuit.
    - ECU pin out test for ignition transistor per fsm: continuity exists and 0 resistance in circuit.
    - spun the dizzy by hand with ignition on and injectors are firing, so I assume the CAS has no issues?
    - again the coil has 12 v going to it and also 12 v on the other side (coil wire).
    - disabled security system entirely

    Since it SEEMS like the wiring is ok based on the continuity tests, is it reasonable to assume the ECU may be the cause? I stated earlier that I tried starting it with a spare ecu but i'm a little iffy because it's an 84 N/A ecu…that being said, a n/a ecu should start a turbo car yes? it just won't run well? please correct me if i'm wrong. Also, I noticed that when I plugged in the 84 n/a ecu and turned the ignition ON, the fuel pump would not stop priming. is this because wiring/connection terminals changed over the years or is it a possible ecu problem?

    Lastly, is there a way to test if the ECU is sending signal to the coil for when to fire without the use of an oscilloscope?

    Sorry for all the questions, just really wanting to drive this thing and get it running again,
    thanks

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"
  • zdriver_kado
    zdriver_kado
    Member
    • 100

    #4
    I've had a similar issue dealing with the PWR2 transistor wiring. It may be worth trying to use a different ground wire instead of the wire originally going to the transistor. From my experience I couldn't get spark unless I took ground from a nearby unused connector.
  • zlover23
    zlover23
    Senior Member
    • 291

    #5
    Really need so help here guys…car still won't start but we have narrowed down a lot, here's what we've found so far:
    - new prw-2 power transitor
    - new coil
    - 12 volts power going to power transistor with key on.
    - 12 volts power at coil with key on.
    - confirmed pulse signal when cranking engine at 2 wire coil connector ( so that confirms CAS, wiring harness, and ecu is working properly correct?)
    - both the coil and transistor are mounted very secure to their mount with bolts

    so what the hell could it be? There is power going to the coil, and a pulse signal going to it as well; the power transistor and coil are both brand new and grounded to their mounts well. Also tried a new ignition switch assembly thinking maybe a contact in the switch could be burned out, but made no difference. Is there a separate ignition ground somewhere I'm missing? The coil is grounded through the case right?

    PLEASE HELP
    Last edited by zlover23; 08-08-2016, 09:36 PM.

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"
  • shromy
    shromy
    Senior Member
    • 2189

    #6
    How are you testing for spark At the end of a plug wire or by pulling the coil wire itself off
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • zlover23
    zlover23
    Senior Member
    • 291

    #7
    Both with a spark plug attached to the end of a plug wire grounded to chassis and also with a spark plug attached to the coil wire grounded to the chassis and neither have spark. Ohmed out all the wires and they are all good

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"
  • shromy
    shromy
    Senior Member
    • 2189

    #8
    From what all you have listed and the checks you have done that leaves only the coil, which you have replaced. give me a bit to go through the fsm.
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • shromy
    shromy
    Senior Member
    • 2189

    #9
    disconnect the coil plug and tell me what voltage values you have with the key on
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • zlover23
    zlover23
    Senior Member
    • 291

    #10
    12 volts at the coil plug with ignition on....but here's the weird part: I inplugged the PTU harness and removed the loom to inspect wiring for damage, and now I have no power going to the power transistor with the key on. I rechecked for continuity at pin 3 and 5 off the ecu to the end of the wires at the PTU harness and continuity is good. I still have 12 volts going to the coil connector but none to the power transistor. I'm at a loss right now, I'm thinking there has to be a ground issue somewhere but don't even have the slightest clue where to start with that.
    also, I checked for 12 volts power (with key on) at the ecu by back probing the harness at pins 3 and 5 again and there is no power there either, so the ecu isn't even sending voltage to it. I have 3 other ecus so I tried hooking them up to see if that would change but it made no difference; still no 12 volt reference coming out of the ecu for the power transistor circuit.

    is there a dedicated ground for the ECU or anything like that?

    Starting to lose hope for this thing

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"
  • zlover23
    zlover23
    Senior Member
    • 291

    #11
    EDIT:
    i also noticed my fuel pump is no longer priming when I turn the key to ignition, and according to the wiring diagram per fsm the PTU and fuel pump relay both share the same ground, does anyone happen to know where this might be?

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"
  • 88sinZ
    88sinZ
    Senior Member
    • 2019

    #12
    If I had the same issue the first thing i would assume is the CAS or a shoddy ground in an ignition circuit, if you'd like to double check your troubleshooting for the CAS or Coil/PTU it's on EF&EC-84/92

    The ground your looking for is 11F &4F Both are located on the Pass EFI harness, 11 is right near the battery coming out of the main harness before it splits, it should be bolted to the firewall. and 4 is towards the end of the harness forward of the injectors, it should be bolted to the upper intake manifold.

    REF: EL-190 for location and EF&EC-92 --- as for how they're related: one provides ground to the safety relay so the fuel pump receives power, the other provides the ECU wire shielding ground. The ignition circuit doesn't note which body ground is used in the diagram so i'm not sure if it's much related unless you traced through a schematic to verify.
    Last edited by 88sinZ; 08-09-2016, 03:24 PM.
  • shromy
    shromy
    Senior Member
    • 2189

    #13
    with you coil unplugged you should only have 12v on the g\w wire. the blue wire appears to be the ground\switch. ptu shares the blue wire with the coil(blue), has its own ground(black), and signal to ecu by green\black. if you have 12v on both coil wires, coil unplugged, there is an issue.
    Hmmm, Whats next?
    Full Size Bronco, smashing shit.

    84ZXT
  • flatfoot
    flatfoot
    Senior Member
    • 253

    #14
    Dumb question.

    You did swap the wires when you did the prw2 right??
    Life's short
    Go fast
    Have a blast
    Leave a good looking corpse
  • zlover23
    zlover23
    Senior Member
    • 291

    #15
    thanks for the input 88sinZ, checked those grounds and they both have good connections.

    Shromy- That's a very good point, I do in fact have 12 v at both wires going to the coil. Any ideas why that could be or where the short could be located? I've checked the harness as far back as I could (to the firewall) but after that it disappears into the very top area of the dash that I cannot get to. According to the fsm wiring diagram, the 3 wires for the ptu go to a large connector, I'm guessing located under the dash, before going to the ecu. Any ideas where that connector might be Sounds like my harness is f*****

    And flatfoot- yes, swapped the green wire with the black wire and left the blue the same

    '86 NA2T: Cone filter, 3 in. turbo back, poly engine mounts, stock t3, tokico 5-ways, rattle canned engine bay, etc etc

    "As I lay rubber down the street, I pray for traction I may keep, and if I do begin to slide, please dear God protect my ride! - Amen!!!!"