Aem Smart Coil Wrx v3-v4 Wiring Issue

[ozzy]

I seem to be having a weird signal ground wiring issue with my new set of Aem smart coils. If i connect REF Ground to cylinder heads it seems to work just fine but if i leave it as is meaning wired to B137-24 car just doesnt start. Wiring itself is ok i checked. What could be the reason for this and can i use the expansion loom ground for ignition ground as i have other sensors grounded to that expansion loom ground.

Switched to these after having misfire issues from my old set of coils ls2 truck coils ds585(bought 2 sets new of coils  run great for 150-200miles and started misfiring above 25psi) 

 

 

[Adamw]

What coil pin are you referring to as "REF"?   Pin B?  

Is your B137-24 pin in position 16 in the link pinout? 

If both of those questions above are "yes" then it sounds like possibly a ground offset between engine and ecu.  These coils use TTL so quite low voltage switching point.  If you could back probe at a coil connector and measure voltage between pin A&B with just ign on, and also when cranking that will give us some clues.

[ozzy]

@Adamw

Yeah i am referring to Pin B

 

 

"Is your B137-24 pin in position 16 in the link pinout? "

Yeah its in 16 

 

Hmm i did measure the voltage between A&B  A&C A&D with ignition on. I dont remember the values but it was all basically same so i assumed grounding was ok. I will measure those again tomorrow and let u know the exact voltage. What would happen if i were to ground Pin B to somewhere else close to where ecu is grounded or maybe coil mount plates instead of bundling them together with Pin C. I have tried to find out some info regarding grounding issues some said  that could result in a blown coil in very rare circumstances (i mean grounding Pin B and C to cylinder head together). Pin D is directly connected to battery ground

BTW thanks again adam you are a life saver every time.

 

[ozzy]

@Adamw

Tried to ground the coils(pin B only) to expansion loom ground. Car misfiring horribly at any throttle input above 80% Here is the log 

Log 2022-12-27 8;06;07 pm.llg

[Adamw]

On 12/27/2022 at 9:33 AM, Adamw said:

If you could back probe at a coil connector and measure voltage between pin A&B with just ign on, and also when cranking that will give us some clues.

 

[ozzy]

@Adamw

pic is pin A&B 

A&C 24.8

A&D 25.7

 

 

 

 

 

 

Sorry for the delay i was pretty busy

 

[Adamw]

Can you check voltage between A/B when cranking.  

[ozzy]

It's between 47.5-49.5 when cranking between A&B

[Adamw]

Ok that should be fine.  I would expect those coils to be happy up with up to about 500mv offset.

So if it runs ok with B grounded to the cyl head then I would just leave it like that, it will be difficult to find why it is not happy with ECU ground without a scope etc.  I have seen many of those coils grounded that way working without drama although I do prefer to have that referencing ecu ground.      

[Stevieturbo]

Modern OEM Subaru COP with internal ignitors work fine even at only 30psi boost.

585's are over-rated, far too many seem to get a hard on over them despite their massive and dangerous flaw of premature firing with too much dwell.

 

Your problem is a strange one. I've used IGN1A's on a few cars ( non-link ) and never had any issues with them. If you are not 100% sure the coil triggering system is working safely, I'd proceed with caution. Sparks firing at the wrong time, can cause big problems

[ozzy]

@Stevieturbo @Adamw

VERY STRANGE 

After a month of changing everything like 3-4 times trying out new set of AEM coil packs twice spark plugs like 4-5 times and coil wires 4 times, another subaru mechanic told me that they have tried the same set of AEM coil packs on a race car and had the same problem.  So i decided to go back to original 2006 setup which immediately solved everything. I simply cant fathom why but apparently subaru dont like AEM coil packs. THANKS for everything again adam. You have been so helpful everytime.