Austarion

I have recently installed a MSD 6AL-2 programmable ignition http://www.msdignition.com/Products/Ign ... 6AL-2.aspx into my JA starion running the factory ECI and ECU system (is heavily bastardised).

getting the ignition in and working has been quite straight forward but i have run into a problem of where to run the coil trigger for the ECU from.

The MSD ignition has a tachometer output which seems to drive the tacho okay but it appears the signal from it isn't strong enough to trigger to ECU into run condition. Apparently an additional tacho adapter http://www.msdignition.com/product.aspx?id=4709&
is required to boost the signal.

I can't use the coil neg- terminal anymore as the MSD box apparently drives the coil at a higher voltage than 12VDC (up to 480v according to the MSD manual)

Just wondering if anyone has used one of these MSD boxes to replace the original ignitor before and how they overcame this issue.

It's the same issue encountered when trying to interface factory older style tachometers to aftermarket engine management tachometer outputs. The older style tach's are expecting to see a big inductive kickback spike, but only receive a 0-12v square wave. However, you probably cant just remove a resistor from the ECU to make it work, like you usually can with a tachometer.

The other solution to the tacho problem has been to use the guts from an automotive relay. You pull apart the relay to get just the electromagnet coil, and power this from your MSD's tachometer output, via some form of opto-isolator to protect the MSD itself. When the MSD cuts the current flowing through the electromagnet coil, it produces the inductive kick-back spike the ECU is expecting to see. As our car's are centerpoint injection, the timing of the injector pulses in relation to engine position isnt really that important, so a little delay in the system isnt a big issue.

You could probably sell the MSD for quite a bit and for not much more, get a Link G4 Atom ecu, which would be able to run your fuelling and ignition together? Or is it some form of racing where you're not allowed to use aftermarket engine management?

Thanks for yuor reply Prozac. It has helped me understand they problem I am facing that much better. I'd say thats probably what the MSD tach adapter is, just a small inductive coil.

Yeah in hindsight I should have just replaced the ECU with an aftermarket unit that could run everything.

The MSD seemd like a good option to replace the old ignitor as it does everything that the old one can but in a more modern way (adjustable advance map and boost retard). Plus I have another project I can use it on when I go twin cam with the staz.

I justified by telling myself it would be easierand cheaper than installing a new ECU but in the end it has been on par on both counts.

wait i'm confused...

if the ecu is expecting a high voltage as Zac said, and the coil neg terminal is run by the MSD at a high voltage, as sucka said.. what's the problem with connecting them up that way?

thrash wrote:wait i'm confused...

if the ecu is expecting a high voltage as Zac said, and the coil neg terminal is run by the MSD at a high voltage, as sucka said.. what's the problem with connecting them up that way?

from MSD manual wrote: Because the MSD is a Capacitive Discharge ignition very high voltage will be present and no test equipment should be connected to the coil pos+ or neg- terminals.
WARNING:Do not touch the coil terminals during cranking or while the engine is running.

just did a quick google and the coil + and - see 420-480v
I guess thats why you cant connect the ecu tach wire to the coil neg-

Yeah, you don't get the inductive kick-back spike with a CDI system, they they use the much lower inductance ignition coils as a transformer to massively bump up the voltage of the energy they dump out of an internal capacitor, when a spark is required. Quite a different way of doing things, and actually pretty cool, and bloody effective! The warnings about not touching things when they're running is well heeded, they can cause you some serious damage.

I'm really surprised that the MSD's tach output will drive a starion tacho without any modifications, but won't trigger the ecu? Do you have access to an oscilloscope at all to have a look at the waveform it's spitting out?

MSD's are so cool though! :)