I found this on the emag site. And am wondering if this was an issue in our planes because of the long wire run?
Thanks,
Dave
A percentage of customer reported an occasional high speed miss. This was eventually traced to voltage shifts on the 12 volt supply buss. It’ was not so much the amount of voltage change as the rate of change that caused a momentary advance or retard of ignition timing before E-MAG’s automatic dwell compensation was able to react. The symptom is buffered to a large extent by the ignition’s onboard capacitors. But a combination of a) longer wire runs, b) lighter gauge power wire, c) load from the ignition (rpm), and d) the size and rate of voltage shifts all work against this buffer. These are conditions unique to each installation. The pattern had not presented on our test bench, our test engine, or on any of the local customer installations, so it was tough to trace down. But once we identified the problem and could replicate it in the lab, the cure was relatively easy. Going to 18 gauge wire for power and ground (alone) will fix the problem for many. If not, we modified the firmware routine (standard now in all units built since 7/5/05) to eliminate the symptom. This firmware modification is available for all E-MAG models at no charge. So far, installing this modification has cured all (but one) of the instances reporting the symptom. This instance is still under study.
