Richard, as we say in the industry, "That's not a bug.  That's a feature."

I have the ability to control what the minimum RPM is before the ignition will fire.  The thinking is that you don't want to accidentally light off the leftover mixture in a cylinder.  The computer needs a way to know for sure that someone is trying to crank the engine.  I can also configure the computer to ignore the initial ignition events.

Does the MSD have a way to modify what it thinks is cranking speed?


---- Richard Sohn <res12@fairpoint.net> wrote:
> I am desperately trying to get the single rotor running in the airplane. The engine on the test stand is just humming away, and when I tried the one in the airplane a couple of weeks ago it did not do anything.
> No ignition!!!  cranking too slow???  starter cable too long??? CAS signal too weak???  
> The ignition fired when I took the plugs out of the rotor housing, but not when they were in the housing. The crank speed difference is 240 vs 320 RPM. The engine on the test stand is already so free that it does crank about 360RPM. Solution? Making a larger diameter trigger wheel to make up for the slower crank speed. Turned out to make no difference. What is going on?????.
> My ignition system is a MSD Street Fire unit. At this point, I decided to have a closer look at the trigger characteristics of this unit. After running it on the bench with all sorts of triggers, it turns out to require a  minimum pulse repetition rate at which it is firing no matter what voltage or wave shape of the trigger signal. On top of that, a build in trigger indicator light works at much slower trigger signal the coil actually fires, creating a deception when testing.
> All that seem to be not a malfunction of one unit because I have two units doing exactly the same thing.
> Before I found out what is going on, I contacted MSD by phone and was told to hook it up correctly, and if it does not fire send it back to them. Later I sent in some more questions by email which were never answered.
>
> Final solution! No CDY. Using two individual coils with a TSI igniter each. No more low speed issues.
>
> Installation on the test stand is complete, and will be tested in the next two days. If nothing bad happens, installation in the airplane will be competed in a couple of days.
>
> I hope this is not to confusing.
>
> Richard Sohn
> N2071U
> www.fairpoint.net/~res12/home.html
>