Interfacing LS2 coils to Microtech EFI & Possibly others! (How to)

[VA61DETT]

Ok,
After a bit of hunting around I was unable to come up a great deal of info regarding connecting the oh-so-popular LS2 coils to my Microtech LT10.
So for the benefit of others I decided to put together a quick guide from my own findings & some reference info (thanks to mega-squirt efi website).

1. Get hold of said coils.



2. Find pinouts.


Stolen from:
http://www.megamanual.com/seq/coils.htm

3. Examine waveform from ECU output (Lines going to MT ignition module)
Scope output:


May be a little hard to see here, but the waveform coming out of the LT10 has a 12v peak level, dwell is bumped up considerably from the stock Nissan units (about 5ms is what the LS2 coils like).

4. Convert levels

The LS2 coils require only a 5v TTL signal to trigger, they are fired on the falling edge of the pulse.
I constructed a simple level converter to safely convert the output of the LT10 to 5v. In my case I have to use a wasted spark setup, so the outputs are grouped.


5. Wire em up


I chose to use shielded cable from the output of my level converter to the coil packs, the signal grounds are connected back to the ECU mounting plate (which is grounded back to the block).
Additional grounding for the power side is bolted onto each head of my v6. The small capacitors are joined & wrapped up within the wire harness.

6. Install & Test

Running the ECU in test mode to make sure everything is happy.

These coils really make a noticeable little crack when they fire off!

Complete coil & bracket assy:


This circuit has now been tested with revised PCB 2.0, I am happy to report that the timing is now working 100% correct!
The idle quality & throttle response has been considerably improved!
Now need to wind in a bit more pressure & see how the spark holds up

-A

[RA35GT]

Nice work Aaron. Them coils be awesome.

[VA61DETT]

I managed to get lone of a storage scope and capture some very useful info regarding my initial coil firing issues.

Notes:
*Manually triggering the coils with +5v can cause erratic behaviour if you are exceeding the max dwell time (~8ms)
*There is a double trigger effect noticeable form the high voltage end (this may be due to current coupling effect, from just sticking the probe next to the HT lead )

Stock VG30 Coils & MT IGN Box, Channel1 on the ECU output signal, Channel2 near HT lead.


LS2 Coils running in 'inverted' firing mode, Note the small spike, delay, full spark (this was my ignition retarding issue).


LS2 Coils running 'non inverted' mode, This is the right way to do it!


-A

[stradlater]

For what it's worth mate, the guys at Haltech are very knowledgable on those LS1 and LS2 coils.

I use Haltech products, so that might be why they are happy to provide support however you may be able to ring them with some specific questions about the LS2, (leading edge, dwell time, etc..) and they may be able to provide some help?

[VA61DETT]

-stradlater

Cheers

I think I have finally worked out what is going on, will test & post results tomorrow

-A

[VA61DETT]

Ok,

Just to let people Know.

The circuits have all been tested successfully in my ECU set-up.
Keep'n it simple was the winner!

-A