MSTS explained

[Ply]

Hi All!!! Question... aside from ignition, on the 454XL motors, what is managed within those MSTS boxes house on top of the motors?? I've replaced my ignition with Pertronix.. but I often wonder what ELSE is controlled within those little mystery boxes??

 

[makomark]

Just the timing....they were the prototype the MEFI-1 systems were developed from (though I've never seen that in any GM documents). They are rather complete in what they sample.

 

[Ply]

Yeah I'm carb'd, and frankly love it...

Just the timing....they were the prototype the MEFI-1 systems were developed from (though I've never seen that in any GM documents). They are rather complete in what they sample.

Sort of sets my mind at ease as I'm a XXL jumbo and I'm in the middle of doing my impellers, which requires me laying atop/across/around entire top of motor and I always worry about those darn little boxes and the wiring inside....

I know not everyone is a fan of Pertronix (Hall Effect), especially in salt environment but thus far I have no problem recommending it as again SIMPLE... I will tell you this, Cap AND Rotor are absolutely essential replacements EVERY year on my system as the "green mountains" that build up are amazing and she will cough a bit if you neglect new CAPS ANNUALLY....

Sounds like in my case, Mark, I've bypassed it all but in back of my mind somewhere I wonder what fully disconnecting that unit would do??

Things that make you say hmmmmmm....hahhaha

 

[makomark]

I know of a few that have disconnected the box and haven't heard of any issues.

The big thing you trade is going to a fixed timing curve ('hard coded' inside of the EST module) vs having a dynamic (and optimal) timing value based on the operating conditions determined by the MSTS computer. For most marine applications, the load on the engine is significant and fairly constant so I don't think there is a lot of 'economy' being given up...especially with a carb that has a fixed fuel delivery profile...