After installing and running my new XDI, I put the meter on it to check the "real time" timing or advance. The reading seemed to fluctuate a bit, and wondered if anyone has checked timing by this method, and wondered if they had the same result. The ignition works great, despite the somewhat shaky reading by this method. Thank you for any input on this question in advance.

Regards,
Guil

ps this motor runs a racing cam, on webers

First post to the XDI forum! You're a winner!

The timing fluctionuation is probably due to noise on that signal. The voltage is pretty low so it's pretty vulnerable to electrically noisey situations. We once had someone datalog the timing output. He saw the same thing, and asked the same question. It's just the output that does that. If you're timing light says the timing is stable, it's stable.

I'm running into some similar issues also. Last year I noticed the timing seeming to retard with rpm's according to my timing light. Eric Falk told me it was most likely EMI from the coils, not the timing itself changing.

Now this year instead of moving knobs to try and get the timing light to read a consistent number I attempted to read the output with a simulator box and a multimeter. Surprisingly the indicated advance (with the 8000 knob on zero) will climb 20 degrees or more with rpm. If I unhook the coils and run the same test it is rock solid with no timing change showing.

What I'm wondering is this just more interference from the coils? If I leave them unhooked and set my desired advance numbers can I count on the box to hold those numbers when the car is up and running?