top end misfire - interference ?

[tonyb]

hi all - i've installed a megajolt system on a racing hovercraft powered by a 2 stroke 500cc SkiDoo snowmobile engine - we run a simple 2D map as loading on the fan is pretty consistent and we spend a lot of our time flat out around 8500 rpm

it starts first pull every time and revs very cleanly up to 3/4 revs but mis-fires if we try to hold it flat out, we've tried all combinations of maps from flat to typical 2 stroke curves and the misfire always persists, we run off plugs 1 and 3 with 4 and 2 connected to the engine earth, the pickup and megajolt wires are shielded as per installation instructions/circuit diagram

more alarmingly it has cut out twice for no apparent reason only to start again as soon as the megajolt is switched off/on again and it isn't being starved of fuel

could it be interference and how to check, can the coil/Edis4 keep up at 8300 rpm any suggestions welcome

p.s. the other issue is trying to run the software realtime, it allows us to read/write/flash the map but software locks up with 54 reading on the tacho if we start the engine

cheers Tony

[Spockie-Tech]

When I was bench testing Edis 6 Modules I found this sort of behaviour..

They seem to have an internal rev-limiter. The two units I had had different colored stickers and part numbers, and showed repeatable consistent results.

exceed a certain rpm and the spark shuts down. It ewont come back unless you do a power cycle or bring the revs down near idle.

I think my 2 modules ran to about 7200 and 7800 rpm (green and orange IIRC).

Sounds like you might be hitting the EDIS internal limiter