jsmcortina wrote:I've passed this on to Bruce Bowling for comment.
shaodome wrote:Would this thread (or any future 3X hardware questions) be better served on the MSefi forum as opposed to here?
jsmcortina wrote:shaodome wrote:Would this thread (or any future 3X hardware questions) be better served on the MSefi forum as opposed to here?
I believe you'll probably get banned if you mention MS3 over on MSEFI.
subwoofer wrote:From the schematics it looks to me as there is no overvoltage protection on the injector driver FETs. A voltage spike may or may not occur, but if it does there is nothing on the MS3X to arrest it. A set of Tranzorbs (BZX series or equivalent) would add peace of mind. I favour Tranzorbs over regular Zeners for this purpose, I have killed too many microphone preamp circuits that I had attempted to protect with regular zeners.
wes kiser wrote:Just wanted to comment I have used the MS3x on my personal vehicle for many thousands of miles with no issue (which with 12 ohm injectors is admittedly not surprising).
Perhaps a more useful comment is I have a microsquirt module based adapter board, that must occaisionally support a pair of low z injectors per driver(which uses the same injector drivers). The way I handle this is with a series 3.3 ohm resistor, which allows right at 3.5 amps per channel when used in series with a pair of low-z injectors. I have several of these boards with quite a few miles as well.
Hopefully you find the root cause/resolution. Two different boards likely can't be attributed
Peter Florance wrote:I believe the FET's are have built in clamping.
racingmini_mtl wrote:If you look at the data sheet, there is protection on the gate side also. So the input and output sides are protected and there is thermal and over current protection. So it should be quite difficult to make them fail. And a single high Z injector should not be a big load unless these particular injectors have an unusually high inductance which would generate a lot of flyback energy.
subwoofer wrote:Dropping a cylinder intermittently is consistent with the protection circuitry kicking in. I'll read the data sheet properly later tonight, I need to understand how the overvoltage circuit works.
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