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SR20DET no spark while cranking, ignition spark test good


Jeffrey

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All I am currently trying to do is set base time on the ECU but while I crank the engine, I get no spark. I have an SR20DET redtop, stock CAS but 350Z smart coils with an ignitor chip bypass. I know this setup works because when I switch back to my stock ECU the car fires right up. The coils should be getting power even while cranking because it shares the same relay switch as the ECU, so if the coil harness isn't getting power then neither would the ECU itself. I can run the Ignition test on each individual coil and they all spark. See the attachments for my map and logs. Maybe someone can tell me what I am missing?

PC Datalog - 2024-05-5 5_52_10 pm.llgx SR20DET - MAP.pclx Trigger Scope - 2024-05-5 5_49_28 pm.llgx

I am using a timing light to confirm spark. When I did the ignition test, I did it by both timing light and removing the spark plug and coil and grounding it to visually see and hear the spark.

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You can see in the log there is no RPM when cranking - so this means the ecu is not receiving an acceptable engine position signal.

In the trigger scope we can see the issue is the voltage of trigger 2 is low, it should normally be around 3.5V, but yours only reaches about 1.85V.  It needs to go above 2.0V to be considered a "tooth" to the ecu.   Trigger 1 looks ok at 3.43V.  

The first check I would do is unplug the CAS and do another scope capture (dont need to crank), if trigger 2 then shows ~3.5V with the CAS unplugged then that confirms the ecu pull-up and wiring is ok, and the problem must be in the CAS. 

If the voltage doesnt improve with the CAS unplugged then that would suggest a partial short in the wiring or an issue with the ecu.  I will give further instructions on how you could test those later once you confirm voltage with CAS unplugged.  

ztRpouH.png 

 

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I just measured the power output at the CAS connector with both the LINK ECU and the stock ECU connected to see what the differences were. Just with the car in IGN ON position, no cranking.

Stock ECU Trigger 1

LINK Trigger 1.jpeg

 

 

Stock ECU Trigger 2

LINK Trigger 2.jpeg

 

 

LINK ECU Trigger 1

OEM ECU Trigger 1.jpeg

 

 

LINK ECU Trigger 2

OEM ECU Trigger 2.jpeg

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I think since you have lower voltage on trig 2 pin even with the stock ecu suggests there is a short in the wiring.  Can you pull the trigger 2 wire out of the ecu plug and do another scope to confirm if trig 2 voltage returns to normal.   

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I have to see if I can find a tool to de-pin Trig 2 at the jumper harness, but I can probably do it at the CAS connector. I did run two other tests. 

 

1st I bench tested the Link ECU, hooked it up to my 12V power supply, checked voltage on Trig 1 and Trig 2 and both pins are putting out 4.06V

2nd test I checked the resistance of the Trigger 1 and Trigger 2 wires going from the CAS connector to my jumper harness and both show 0 resistance.

 

I'll post up results soon of the scope capture with Trigger 2 de-pinned.

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I just meant depin trig 2 at the monsoon plug.  Which you have now effectively done by bench testing the ecu anyhow.  So it appears you have something between the ECU and CAS plug affecting trig 2 voltage.  

The next thing I would do is unplug the monsoon and the CAS, then at the monsoon plug, measure resistance between pin 7&8 and 7&9.  There should be "OL".

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So I gave it another check and my cars battery dipped below 12V so I have it on a tender to recharge it (too much cranking). But the trigger scope looks the same on Trigger 2, live and before cranking it only sees 2.08V and while I crank it goes down to 1.86V.  I swapped back to the stock ECU (to troubleshoot) and it fires right up.

I've included my wiring diagram, even though it looks all good, but maybe someone can see if I messed up somewhere?

Screen Shot 2024-05-06 at 11.09.25 PM.png

STOCK ECU pinout.WEBP

Wired to chassis.jpg

On the chassis wiring digram, I've removed that fuse that goes to Red (ECU Back Up and injector power). On the relay labeled IGN/RUN that switches on pins 38,47, that is what powers on the CAS.

 

 

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The "3.5V" that you should see on the trigger signals comes from the pull-up inside the ECU, it is not related to power supply or ground to the ecu or CAS.  The only thing that would cause a lower "open" voltage to be seen at the ECU on the trigger 2 signal is "load" on the trigger 2 circuit.  I.e there is some extra load "pulling down" the voltage.  Its not the CAS as you still have the same low voltage with the CAS unplugged.  Its not something internal in the ecu as the voltage returns to normal with the trigger 2 wire disconnected.  

Does your loom have any wires in positions 22 or 40?  Does unplugging TPS, knock, oxy and temp sensors make any difference to trig 2 voltage?

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FIXED!!

Thank you for pointing me in the right direction. For whatever reason, I was tapping off the Trigger 2 signal to run my tachometer. I don't remember why I did it like this and not use the actual tachometer output signal. But once I removed the wire going from the tachometer to trigger 2, I ran another trigger scope and I get RPM now. I've uploaded the results, just because. Hopefully I can continue and finish to get my car running on the Link ECU. 

Trigger Scope - 2024-05-7 8_57_01 pmGOOD.llgx

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So I'm making progress little by little. I was able to get spark while cranking and set my base timing (fuel injectors disconnected, just cranking the engine). But now with everything connected back I am getting Trig1Err every full rotation cycle of the crank. I don't know what settings I can check since the Nissan 360 Opto options are limited. Trigger 1 and Trigger 2 set to the default for that option. I've included a trigger scope and log of me cranking.

I initially had my ECCS relay to kick on when the Batt Voltage was >=8V but it seems my battery isn't as strong during cranking and my ECCS relay wouldn't stay on. So I've now set it when my ECCS relay is "Inactive" (which then makes it active) and it now stays on when the ECU is on.

PC Datalog - 2024-05-10 8_39_35 pm.llgx Trigger Scope - 2024-05-10 8_39_42 pm.llgx

UPDATED MAP

SR20DET - 510.pclx

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8 hours ago, Jeffrey said:

So I've now set it when my ECCS relay is "Inactive" (which then makes it active) and it now stays on when the ECU is on.

Its going to turn off momentarily every 0.24s from that as far as my logic suggests.  You should set your condition to something that is always true, such as Batt voltage > 1V or BAP > 10kpa etc.  

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Thank for your clarifying that. When I initially set up my condition I used the 'Internal voltage' and I couldn't go below 8V but using the 'Batt voltage',  I can set it up just as you suggested. Hopefully this keeps my CAS powered and trigger error free. 🤞

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I gave it another try, leaving the delay off at 0 on the ECCS relay but I'm still not popping off. I'm still getting Trigger 1 Errors, it seems every 720º rotation of the crank. I also tried switching the Trigger Mode to Nissan 360 Opto Widest Slot with both 16 and 17 widest slot teeth, and this helped some with fewer trigger errors but they are still there, so I just put it back to the original 360 Opto mode. It's like the car isn't even trying to kick off. I would think from so much cranking and priming the car would at least pop off and die, but it just cranks. Here are my latest trigger scope and log.

PC Datalog - 2024-05-11 12_38_19 pm.llgx Trigger Scope - 2024-05-11 12_37_54 pm.llgx

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OK, so I finally got everything buttoned up and the car now turns over.

 

I had misdiagnosed this as a trigger error issue but going through the forums, those errors are normal when cranking and stopping when the car doesn't turn on. I had an earlier issue with the relays staying on after I turned the car off, which I thought was due to that ECU Back Up fuse still being connected. So when I tried cranking the car over, my injectors were not firing, because I was missing that ECU Back Up fuse, which powers the injectors (you can see in diagram, says 'Back up and Injector Power). Once I got that fuse back on and cranked the car, it popped right off. I have to see if the last log I uploaded shows the injectors actually firing. But at least now I can start tinkering on the tune. :D

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