MS3 Goldbox Spark cut limiter with TFI??

James408

Member
May 18, 2020
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Ok so before anyone goes "wheres your patients do a search please the info on tfi not working with spark cut is everywhere." Which is true. Lol But I have a ms3 goldbox from efi source on my 1986 mustang gt and the thing is spark cutting but in a strange way. 2 step setup I hit it and if you have heard spark cut on a 5.0 its pretty violent fast limiter and pops and the sort. It does this until about 1/3rd or so throttle input. Any more throttle than that it stops being violent and does a slow fuel cut sounding limiter?? I know the violent spark cut builds boost. Reason I'm trying to figure out whats going on is because I want to go boost very soon and be able to build a decent amount of boost. If I can stay stock tfi for boost that would be less expenses on msd or edis but maybe its an issue. I'm just trying to learn how this all works. Is the tfi still restricting how well this can work? From all the other threads I have read I'm surprised its even cutting spark. No i dont have a msd box or any ignition box all stock 86 tfi ignition. Any ideas? I'm gonna ask efisource today see if they know what they did to take control of the coil. they must have took control of the coil alone from the tfi to be controlling spark like this.
Edit: just got off the phone with efusource. They said that it does have some but only some control of the spark cut. The tfi is the problem what is happenening is under lighter throttle the tfi is allowing spark cuts and timing retard (to an extent). Then under heavy throttle it goes into the limp mode and reverts to 10 degrees and just forces all spark to cut off then on then off slow limiter thing im having. So now I have to still ask. Msd 6al will it work to bypass the tfi with a ms3 goldbox? I'm imagining it will but want to be sure
 
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Sort of..

The TFI is going to act with spark cut like it would when you remove the spout, then it will fire on the rising edge of the pip pulse. This is the issue, the TFI will NEVER fire below its mechanical timing nor will it truly spark cut.. it sorta just acts weird.
You do have options, an MSD box can be fired from the MS directly for true spark control or you can do direct coil control with an IGBT such as the bip373 or an equivalent...
I lots of products out there capable of driving the coil, keep in mind the TFI is current limited to 8amps you dont want much more than that otherwise the coil itself will start to overheat and fail.
I am working on a prototype TFI driver now but its in the testing stages. if you want to be a tester PM me.

you could also use a coil driver from efisource or diy.
The TFI does the job it was designed to do but most of us ask more than that of it.
 
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James408

Member
May 18, 2020
18
4
13
24
New York
Sort of..

The TFI is going to act with spark cut like it would when you remove the spout, then it will fire on the rising edge of the pip pulse. This is the issue, the TFI will NEVER fire below its mechanical timing nor will it truly spark cut.. it sorta just acts weird.
You do have options, an MSD box can be fired from the MS directly for true spark control or you can do direct coil control with an IGBT such as the bip373 or an equivalent...
I lots of products out there capable of driving the coil, keep in mind the TFI is current limited to 8amps you dont want much more than that otherwise the coil itself will start to overheat and fail.
I am working on a prototype TFI driver now but its in the testing stages. if you want to be a tester PM me.

you could also use a coil driver from efisource or diy.
The TFI does the job it was designed to do but most of us ask more than that of it.
Thank you for the information! Cleared that up alot. Ill shoot a PM about that.