Forums/Z31P/z31-performance-upgrade-forums electronics-aa/no spark, need advanced help
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zlover23: (2016-06-20 22:01:14)
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!
pokeyquick: (2016-06-21 14:52:46)
Check ignition relay, on driver side kick panel, 3rd relay.
zlover23: (2016-06-22 01:25:41)
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
zdriver_kado: (2016-06-24 14:14:03)
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: (2016-08-09 02:33:29)
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
shromy: (2016-08-09 11:39:58)
How are you testing for spark At the end of a plug wire or by pulling the coil wire itself off
zlover23: (2016-08-09 14:54:36)
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
shromy: (2016-08-09 16:18:34)
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.
shromy: (2016-08-09 16:38:52)
disconnect the coil plug and tell me what voltage values you have with the key on
zlover23: (2016-08-09 17:43:06)
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
zlover23: (2016-08-09 18:34:33)
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?
88sinZ: (2016-08-09 20:08:03)
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.
shromy: (2016-08-09 20:20:08)
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.
flatfoot: (2016-08-10 03:59:54)
Dumb question.
You did swap the wires when you did the prw2 right??
zlover23: (2016-08-10 17:23:20)
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
zlover23: (2016-08-10 17:32:24)
Here is what I'm talkinh about per page 9 of "EFEC" in the fsm, sorry for the janky quality
shromy: (2016-08-10 21:34:21)
unplug the ecu and see if you still have 12v to both. if you do, something shorted somewhere. but who cares, run a single new wire from the ecu to the coil and be done with it, way easier than trying to find where it happened.
zlover23: (2016-08-11 00:37:39)
I ran 2 new wires, one off pin 3 and one off pin 5, to the ptu and still has the same issue…which makes no sense to me. I will try running a new ground as well tomorrow when I get the chance to work on it
I leave for school on Monday so I only have a few more days to get this figured out…hooray.
88sinZ: (2016-08-11 01:01:44)
On the schematic diagram (EFEC-92) the connector has a circle with a number in it, that's an ID for the connector. You then ref. EL for harness connector locations.
So, The coil and PTU go through Connector 83M, we see on EL-182 it's location. You can skip inspecting that connector (83M) by confirming continuity at the coil/ptu terminals and the ECU plug. If you confirm good continuity you can safely assume there is a input/output signal issue or a faulty component.
You're correct to say if you have good pulse signal at the coil that the PTU and CAS is working correctly. You're also correct that the coil should see 12V/12V on 1/2 pins.
Don't give up bro, these solutions usually turn out to be very simple fixes. Can you provide any background on any work performed close to the origin of this problem? is your main ground near the starter clean and secure? If you hook up a timing light with the #1 plug in, plug wire connected, and crank the engine does the gun pick up any EMF signal?
I highly, highly doubt it's an ECU issue, but EFEC-139 to 142 has ECU signal info and values
zlover23: (2016-08-11 18:31:19)
88sinZ, which fsm are you looking at? The one I downloaded for 1986 Nissan 300zx doesn't have an EFEC 139-142…it ends at 109
zlover23: (2016-08-11 20:39:19)
is it possible that running an aftermarket ignition system like MSD 6AL will just bypass this stock system and fix the issue? I'm not really familiar on how you run an aftermarket ignition system as ive never done one, but id assume you just need a good ignition signal from the ECU (which I have) and a good switch power and ground, correct?
Because In all honestly, this is really mindf****** me…I ran my own 2 wires off the pins 3 and 5 to the ptu so now I have 12v switched power at the ptu and a confirmed good ground, I have 12 v switched power (from the same blue wire) going to the coil, and I have ECU signal pulse at the coil as well. The coil and ptu are both brand new, along with trying other numerous coils and ptu's. It makes no sense. There is definitely a short somewhere in the stock ignition wiring or something, but ive completely bypassed it by running my own wires. checked as many grounds as I possibly could including the main ground at the starter.
88sinZ: (2016-08-12 02:43:25)
88sinZ, which fsm are you looking at? The one I downloaded for 1986 Nissan 300zx doesn't have an EFEC 139-142…it ends at 109
I like to reference the 1989 FSM, as it's the most up to date revision - disregarding the year differences. But the PDF available online has a horrible flash-through-scan-job. So i normally turn to the 1988 FSM and proof read with the '89. NICO club has hosted FSM's for viewing or download.
But first - chill out, take a day off and just tinker/read eyeball your harness, i understand your on a time constraint. Print off a few DTC troubleshooting pages and ID some locations and pins. Plan an attack and take some notes.
I know it sucks, but we've got to ensure that the steps are followed correctly, the process in the FSM *will* locate your problem.. it just takes some tedious grunt work on your part. You *will* find the cause, ya gotta do the cooking by the book to make a pretty cake bruh.
Be careful jumping wires, you don't want to fry a diode. Don't sweat man, step back and try to go step by step, have any electronic guys that would lend you a hand/eye?
Running a 6AL uses the coil terminal wires, so if there's any issue feeding the coil an aftermarket system will not work. The OE coil is pretty hot by standard anyways.
Z-Whipped: (2016-08-15 07:58:02)
When did you do your NA2T work? Did you use the Turbo Harness or the NA Harness. I can't remember right off hand the exact pin changes I had to make at the harness connector you are showing in your image, but they had to be done for me to get spark after doing the swap, I remember them specifically having to do with pins 3 & 5 as well as a few others had to be changed at the same location. The physical location of the plug is right above the ECU. On the EFI Harness you have the three plugs that plug into the ECU and then one more that plugs right above the ECU into the main harness which then routes to your ptu, coil etc. Just had to look at the wiring diagrams and make note of the differences in pin placement for "E" or "ET"
Ski300zx: (2017-02-26 23:54:52)
if you remove the distributor, ground it, go key on engine off, hook a noid light up to an injector connector, and spin the distributor by hand (spin by the gear, not the rotor, so u dont get shocked) does it pulse the noid light on the injector?
Also, do you have access to a scope to scope the CAS signal and primary signal to the coil?
Ski300zx: (2017-02-27 16:25:45)
Wait a second, you have no spark and the fuel pump isn't priming when you go key on? Check power going to the computer, the wiring for my ECM relay went out on my car, I had to rewire power to my computer.