How to trigger 2 wire coils????

[SeanDean]

I have some gixxer coils that I very badly want to use on my engine, but I don't know exactly how to trigger them.

From what I can tell the stock 1995 ECU uses a positive trigger signal to the ignitor boxes (which are just 4 channel power transistors) and then the ignitor sends a ground to each coil.

I know that the coils all have a constant power when the ECU is on because it is a simple relay that sends them power, just like the injectors.

Gixxer coils are 2 wires which means they need a constant ground and are positive triggered. If the ECU sends a positive trigger already then I think I might be able to just bypass the ignitors, but I don't know if the voltage the ECU send is enough, or even if I could possibly burn out my coil drivers in the ECU with too much load???

I was thinking about giving the gixxer coils constant power and just using the existing ignitor setup to send ground trigger, but I dont know if it will respond fast enough because the ground will have to feed both internal windings.

Heres a drawing to maybe help.



Thanks in advance guys!

[Q45tech]

The coil primary draws 10+ amperes to charge, the ecu transistor can only handle 1/2 an ampere at most and will fail instantly due to ring back oscillation [ voltage spike] as you open circuit to discharge secondary.

Oem coils are great when used with proper driving transistors, not sure if oem driving transistors can properly control any other coils.

Things must be matched pretty close for logevity.

Have oem coils on my 17 year old 317,000 mile Q never a failure.

[SeanDean]

Problem is I have 1995 coils on a 1997 engine. The 1995 coils dont bolt down on the 1997 valve covers. They are also kinda big and clumsy. I am going for an ultra-clean appearance and the GSXR coils will really help that goal.

What if I give the coils constant power and just use the existing ignitors to control the ground like it does already, but now it will be grounding BOTH internal windings......

I really appreciate the reply

Another thing. The 1997 coils do not use ignitor packs, so I assume they each have an internal power transistor, meaning I could potentially wire the 1995 ECU directly to the trigger terminal on the 1997 coils??

-Sean

[Q45tech]

Or the 96 and later ecu has larger switching transistors inside ecu that can handle the surge.

Something I've never looked into. The primary is ~ 0.5 ohms and should read the same regardless of ohmeter lead polarity whereas a transistor will react differently with ohmeter as you reverse leads.

Finding an accurate under 1.0 ohmeter will require a more than typical unit.

All coils have a constant +12v and the ground is closed to charge then opened to discharge the primary magnetic field into secondary creating the spark.

Dwell or charge time is critical in that it much match resistance and inductance to transistor and the internal zener to protect transistor.