Hello all and thank you for taking the time to read this. - I'll try to keep it short and sweet while still giving all the info I have.

-Long story short, I have no physical spark.

-One main question I have is...... Isn't the AEM supposed to be able to send 5v signal to coil packs to fire with or without the PTU? - Can't I just have power and ground to ignition coils provided through the ignition coil relay and have the AEM just send 5v to the signal wire and wallah spark?!?


When I first attempted to fire up the car, I removed the series 1 PTU completely by running the wires directly as they should. I went from pin 1-6 on one end of the connector to pin 1-6 on the other end of the connector and leaving pin E (ground) off.

The car did not start.

I then reinstalled the series 1 PTU and still no fire up.

The coil packs are getting 12v power and they are getting their ground. I can see in the AEM software that the EMS is firing coils 1-6. (Video provided) - The weird thing with that is when I'm not cranking, the EMS is still showing some flickering on the coils as if they're trying to fire. I don't believe what I'm seeing is true however.

With the PTU unplugged, the coils still got their power and grounds from the ignition coil relay. I then left the PTU unplugged and ran a wire straight from the AEM ign1 signal wire to cyl1 coil pack signal wire.

Still no fire up.

I tired that same scenario with runny a direct signal with the PTU installed and still no luck.

I didn't not test the PTU as I seem to get myself flustered with all the online threads on how to test it. The owner of the car is shipping me a new s2 PTU and sub harness.

So to recap everything I did or tried:

AEM CAS disk in CAS
Injectors are firing
Software in AEM is showing it is trying to fire the coils
12v power to coils
Coils have ground
Signal wire ran straight from AEM to coil pack with PTU plugged and unplugged
Speed density conversion but no map sensor currently installed. (Should run tps based)

The ignition coils are showing 0.6 ohms and I think that should be good even though online it says 0.7 ohms or better. The car sat for 4 years and I doubt all the coils just randomly went bad. - Again, this is a VG though.

I believe my next step is to try and get another stock CAS or CAS wheel to try and fire up with the stock ecu. Before I source a CAS, USPS should be dropping off the MAP sensor, S2 PTU, subharness

Thanks for reading. I'm lost on this one. I'm just a hobbyist that's pretty decent or so I thought. I usually take on a few customer projects a year. Ive don't built rb's s1 through Neo, 1j, 1.5j, 2j, KA's etc all running on AEM or Haltech. I took 4 years off of cars just settling into my new family life etc and im faced with this. Kind of a sucky predicament to come back too but it is what it is. Im sure you guru's on here can assist me in sorting this out.

- The security light on the dash keeps flashing but I don't think that'll cut spark and stop it from firing up.

I'm fairly sure the sec light should only be a problem if it goes solid with the key on, but that depends on the vehicle and not the engine. Your problem may be signal voltage and not presence or absence. Most Nissan COP's expect a 12V level on the transistor base and 5V may not fire them. You can broadly test that by tap-tapping a coil trigger on a 5V reference supply (although that may not hold if there are any issues with pulse duration). If 5V is sufficient to fire the transistor, you should see spark every time you remove the jumper from the 5V source. No fire will mean you probably need to step the signal to 12V.

Thanks for the response.

You are correct, I believe that is my issue. I will explain it in another way so you can let me know if I am following correctly.

After re-reading my initial post it dawned on me. - I was not able to find proof of someone removing the PTU on a VG without running some type of smart coil. LS coil etc.

My guess is that the AEM can not fire the OEM VG coils without the help of the PTU.

You mentioning that the vg coil may need a 12v ref and not a 5v ref could be the reason why the coil isn't firing with direct signal. The PTU has to be the culprit. At least I hope it is.

I've always heard of horror stories of the PTU's but the car drove into my garage before I rebuilt it. The chassis then sat for 4 years in the PA weather though until now. (PTU under nose panel) - There was tons of water when I removed the MAF plug, maybe water got into the PTU. Or so I hope. I will test the PTU tomorrow to verify if its good or bad. I've read that the test isn't a 100% guarantee so the owner is shipping me a new S2 PTU as mentioned. - It should be here shortly unless its shipped via USPS.

I run Maxima COP on my personal KA car which is ran on AEM. (Fun 800hp car) - I have some spare coils laying around so I'm going to see if the AEM can fire one using the AEM's signal wire. It simply must work. I'm going to tie the Maxima coils into the same 12 power and ground as the factory coils but run my own 5v signal from the AEM to the Maxima coil. We should get spark. The VG and Maxima coils use the same dwell settings so that's cool.

That test will help me confirm everything involved.

Really appreciate the response. Just responding to you, thinking out loud cleared some things up for me with the system.

-Cheers

You're most welcome. More detail never hurts, others besides you and I will read this post and some may have similar issues. Good descriptions and posted solutions benefit everyone.

Great news.

I hooked up the Maxima COP to the OEM positive and ground wires to the coil packs. I then gave the Maxima COP the 5v reference from the AEM.

Wallah SPARK.

Long story short:

The AEM cannot fire the OEM coil packs without the PTU being in place to send the 12v signal to the OEM coils. (The AEM sends out 5v as we know.) You cant just bypass the PTU with OEM coils and think the AEM 5v can fire the coils.

The AEM can fire smart coils such as Maxima, LS, R8 coil packs all day because those need a 5v signal.

Thank all for reading - Thank you VStar for your time.

I created my profile in 2016 and used it for the first time in 2021. (That's a huge thanks to the detailed search feature)

- Wish you all the best NICO

You can go direct from the AEM pretty easily just by using a 2-transistor step-up for each coil. Very simple circuit if you're handy with solder and breadboard, 2 transistors and 3 resistors. You can easily gang 6 circuits onto a small board in a 3" box.

https://drive.google.com/file/d/1tA4q5K ... sp=sharing

Or you can just buy 6 of these.

https://www.ebay.com/itm/143103138738

Full disclosure, I build those, it's my product in the eBay listing. Major discount for anyone in the forum, just PM me.