No Ignition spark from Coil

1 2 3 Next
  • #1

    No Ignition spark from Coil

    Hello,

    OK, I'll admit it … I need some help. Perhaps some serious help. As the thread title suggests, I have no spark coming from my ignition coil, as I pulled the main high tension cable off from the distributor cap to see if it would make a spark to ground on a frame bolt. Nothing. So obviously, no plug is getting any spark. Overall, here's what's been done on the car so far:
    1) The ECU has been upgraded to a Jim Wolf unit for my make/model. (1985 Turbo 5-speed GL)
    2) A/C unit has been completely removed.
    3) Still has factory turbo but waste gate re-adjusted mechanically to 12 lbs boost. (Higher flow injectors installed --- 420. Matched to ECU)
    4) Power transistor upgraded to PRW-2 and re-wired correctly. (2-wire swap)
    5) Electric water pump. (Direct drive unit with PWM controller --- no conventional thermostat)
    6) Electric fan (switched on/off via thermostatic switch in radiator)
    7) Engine cooldown circuit installed (SS Delay-relay controlled for water pump and fan)
    8) Euro cams
    9) Ported heads
    10) Titan alternator
    11) 3-Bar fuel pressure regulator

    Things I have checked so far:
    1) I am getting +12V to the coil's primary (voltmeter on green/red wire)
    2) Engine cranks just fine
    3) Fuel pump works just fine (stock as of now --- to be upgraded)
    4) Cooldown circuit works just fine as well (works as designed --- timing and shutdown)

    A friend of mine (who's an electrical engineer, I'm a physics/math instructor) helped me with all electricals and mods. Basically, I'm at a a loss, so any suggestions would be greatly appreciated.

    Thank you.
  • #2
    Ohm check the coil. Confirm that the ignition control module (prw2) is working. It needs to get signal through that to fire the coil. Also make sure if that's how you are checking spark, that you are putting a small Alan key or something into the lead of that boot. Then watch it jump from the lead to your ground.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #3
    Thank you for the quick reply.
    Here's what I measured …
    Coil primary resistance ~1.3 ohms
    PRW-2 ground to chassis bolt ~ 5.3 ohms
    As for checking for spark, the boot end that came off the distributor does expose some spring metal which when placed right up to a chassis bolt should make a spark --- but nothing.
    Not exactly sure how to test workings of ignition module (PRW-2) other than swapping it out. I have nothing right now available to do that.
  • #4
    Hmm. Are you using the factory fsm to trouble shoot?
    Also are you sure the wires are installed properly on the prw2? I had this issue when I swapped mine in. Have you touched anything else?
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #5
    Yes, I in fact have the original 1985 FSM … got it a month after I bought the car. (Yes, you've got an original owner here.) My friend and I were extremely careful in re-wring the PRW-2; triple checked everything. I am using the +12V input to the coil as a signal switch for the SS delay relay --- so that is being pigtailed, but the splice checked out continuity-wise. The ECU (I believe) is what grounds out the coil according to engine RPM in order to produce the primary going from 0 to +12 to 0 over and over to achieve an induced high-voltage to the secondary. So in other words, I don't believe the pigtail (which only draws a few milliamps) does anything detrimental.
  • #6
    Try bypassing your splice. Current will want to flow the path of least resistance. Everything should work if it's how your describing, except this delay relay your talking about
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #7
    Sounds reasonable and would lay to rest if tapping off the primary is an issue. But just one thing … this will stop my cooldown circuit entirely, and my water pump and fan will no longer work at all. I'll need to obtain another source of +12V to trigger the system --- a +12V tap that is hot ONLY when the engine is in running mode, not accessory.

    If you would like, I can post the circuit for the engine cooldown which allows for the fan/water pump to run at speed for a set time after the ignition is off. This pretty much eliminates the need to sit and wait for cooldown after a long hot run since the engine is completely off, yet coolant (being cooled by the fan through the radiator) circulates through the block and turbo without any exhaust heat in the housing.
  • #8
    You can probe around the engine bay, try the egr control solenoid connector or the fpr solenoid connector. Or just wire it to the battery with a fuse in line (if you wish for it to run with the car off (I'm not 100% on what the circuit is for)
    Just make sure if your tapping a solenoid or something, that your creating a parallel circuit by grounding it too.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #9
    I've heard of this being an issue with using ignition 12v signal to power a fan control module.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #10
    Does your controller have a hard wire to the battery to keep it running when the ignition is off? Or capacitors? O:
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #11
    Originally posted by NewJerseyZ View Post
    Sounds reasonable and would lay to rest if tapping off the primary is an issue. But just one thing … this will stop my cooldown circuit entirely, and my water pump and fan will no longer work at all. I'll need to obtain another source of +12V to trigger the system --- a +12V tap that is hot ONLY when the engine is in running mode, not accessory.

    If you would like, I can post the circuit for the engine cooldown which allows for the fan/water pump to run at speed for a set time after the ignition is off. This pretty much eliminates the need to sit and wait for cooldown after a long hot run since the engine is completely off, yet coolant (being cooled by the fan through the radiator) circulates through the block and turbo without any exhaust heat in the housing.
    Lol I don't mean to be spamming. If you want to post or pm the schematic that will help.
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #12
    OK … some updates.

    I eliminated the splice with it having no change in anything, except for the fan/water pump not running.

    I have tried to find a +12V tap prior to using the primary coil feed. The most I found was an occasional +7.2V here and there. But I will try your solenoid suggestions. (The EGR solenoid would be nice, since I blocked off the valve port --- it's still electrically/vacuum connected to prevent a fault code.) The pump controller does use a hard wire to the battery (+12 and ground) and is chassis star grounded along with the relays and fan. Basically, all my electronic mods are isolated from everything else, except for the +12V signal tap on the delay relay. Below is the schematic for the cooldown circuit --- the "ignition switch" is the +12V tap. Hope all this helps.

    300ZX Cooldown Circuit.jpg
  • #13
    Next try switching some of the connectors on the prw2
    http://z31performance.com/showthread…2-2-(-now-NA2T
    My build thread (:
  • #14
    If you pull the distributor and spin it, do you get any clicking from the injectors firing? If not, you most likely have a bad CAS. The CAS (crank angle sensor) controls both the spark and opening of the injectors.
    Prius… because Pretentious wouldn't fit across the back of the car…

    Cheap, Fast, Reliable - pick any two

    My 1986 Turbo Build
  • #15
    I believe the injectors are squirting, as after 10 or so seconds of engine cranking one can smell gasoline fumes out the tailpipe. Faint, but clearly noticeable.

    There not being any spark at all going to the cap/rotor seems to me to be the major issue.
1 2 3 Next