MSefi.com read only forum (Jan.15,2018)

im running MSII and i also have an MSD blaster 3 coil

i have dwell duration set to 3ms (MSD tech told me anything between 2.5 and 3ms)

he also told me that max spark duration should be 350ms.

i thought all was good until i looked at the tune im basing my tune off of, and the guy has his max spark duration set to .7ms

thats a BIG difference!!

so what is this setting and how should i set it?


if it means anything, this is for a mitsu 6g72 running the stock distributor with one coil (the msd)

Max spark duration is not a critical number. It is there for the case where you are at very high rpm and have a lot of cylinders like a 6-8 and so the time between cylinders is only 4 ms and you have set dwell as 3 ms and spark duration as 2 ms. 5 ms won't fit inside 4 ms so the ecu scales down the dwell by the ratio of your input dwell and input spark duration It kind of guarantees you will have some dwell off time and therefore some spark. I would leave the default 1 or 2 ms. If you are cruising and have 10 ms between sparks, you will get your full 3 ms of dwell and 7 ms off, with whatever spark is sustained in the chamber - it will eventually go out on its own when the coil has discharged.

i plan on putting max dwell duration to 2.8 (between 2.5 and 3.0)

max spark duration is at .7ms but MSD tech said to put it at 350ms

are you saying i should run a max spark duration of 1 or 2?? im new to this stuff

Yes. I think there was some misunderstanding about the max spark duration. You don't really need nor can you control spark duration. It is what it is after spark starts. But it will never last 350 ms. The tech was probably puzzled by what this variable meant. It really has to do with how much to cut the dwell when you run out of time to dwell and have to start charging for the next cylinder. This only happens at very high rpms.

well i have it set at 8.5 now

the tune i was looking at (is a daily driven tune) was .7 and msd says 350 so i guess it dosnt really matter


i tried to put something ridiculous (to get TS to use a default value and 8.5 was that value)