(root cause found) Dead MS3

[piledriver]

Have been running E85 for the last couple of weeks, ran like a champ, finally got my new flex sensor installed today, plumbed it into return line, reads 65% ethanol, cannot argue with it, temperature seemed sane and rose as it ran...

No issues with the instructions, connected to the MS3X flex input, which if i undertood the instructions is a protected input...
Took it for a drive after setting up the dual tables, got about 5 miles, and it cut off, no comms, no fuel pump etc.

The MS3 is a v0.1 copyright 2009... Perhaps it lacked the input protection circuit that is described in the flex install docs?
Or did I do some thing stupid? I may be making an assumption that the flex sensor install was not coincidental.
There's a nice little melted hole in the cpu, pulls 5v down to 3.3...

I have not hooked the flex sensor up to a scope to see if its still alive, but the output is reading in the lower mv range, not dead or stuck at 12v. The freq counter on my meter can't see it but it can't "hear" very well.

Jacking in an MS2, the rest of the setup seems to work just fine, have already stuffed the MS2 and one of Hardwyres prototype mx2x-mini >MX3X adapters on it so I should be running MS2-extra again tomorrow, have to flash it up to date, I already tested the adapter...
Will have to verify I don't have anything hooked up from the MS3X harness that could hurt.

I could easily replace the cpu, but I understand the monitor/boot loader is kept close to the chest, who can supply or replace it?

[dontz125]

The FLEX pin on the MS3X DB37 is an unmolested straight shot to the JS2 header, and thus to the MS3 card. I don't know what if any protective circuitry is on the MS3 card, but the FLEX circuit on the uS and uSM doesn't seem to offer much to guard against an "oh, crap!" moment.

[piledriver]

I was using this for install documentation: http://www.msextra.com/doc/ms3/flexfuel.html

Excerpt:

The simplest wiring method is using the 'Flex' input on the MS3X. This allows a direct connection to the fuel composition sensor. (The CPU protection is on the MS3 card itself for this input.)

I of course used the MS3x flex input... It was working too. For awhile.

[racingmini_mtl]

I don't know what is on that input on the MS3 card but there is nothing on the MS3X per the schematics. So any protection will have to be on the MS3 card but since the schematics are not public, I don't know what is there. James will have to chime in. If it is the same as on the uS then a nasty EMI spike could be an issue because there isn't much of a voltage protection but rather a current protection.

As for replacing the CPU, it depends on your location. I know that James in the UK can do it and so can I in Canada. I think that Peter Florance and maybe Ken can do it in the US.

Jean

[piledriver]

I'm near Dallas, Texas, need to add my locale...

[racingmini_mtl]

You should contact Perter Florance then. I'm sure DIYAutotune could point you to any other possible option but they will likely not see this until Tuesday (I assume they're close for labour day or rather labor day in the US).

[Chiburbian]

I have a dead MS3 board as well and I have been unable to find anyone to replace the CPU chip as well. Peter Florance hasn't returned any of my emails or PMs and nobody seems to have any ideas of who else can do the job.

I wish you luck and if you find someone please pass it on. It would be nice to get re-chipped if it can be done for a reasonable price.

[piledriver]

Well, his user stats showed he visited the forums at Mon Sep 01, 2014 12:31 am, which (depending if his timezone is set right) is since I posted the thread. Perhaps he doesn't do it anymore...
I might risk Canada Mails perils and hit up Jean if I don't hear from Peter RSN.

Surely someone else in the USA can replace a chip... Should take about 5 minutes, I'd do it myself if the monitor etc code was available.
(I have all the required toys)

Have MS2e-3.3.1 loaded on the box now. Debating trying the ethanol sensor again, wondering if I can make a better protection circuit and put it in the MX2X-minis proto area.

[Chiburbian]

What is involved in swapping the chip assuming you have the correct mounting hardware? You mention something about monitor code? Does it have to be flashed prior to being installed or something? I know nothing about ICs like this.

[jsmcortina]

I don't know what is on that input on the MS3 card but there is nothing on the MS3X per the schematics.

10k pullup, 10k series.

What is involved in swapping the chip assuming you have the correct mounting hardware? You mention something about monitor code? Does it have to be flashed prior to being installed or something? I know nothing about ICs like this.

Replacing the chip itself is "just" a surface mount IC swap.

The monitor is not publicly available and only a very small number of repair agents have it.

James

[93supercoupe]

is this an issue or and isolated incident? I would like to eventually get on e85.

[jsmcortina]

is this an issue or and isolated incident? I would like to eventually get on e85.

I've never heard of it before.

James

[piledriver]

I more suspect it was loose wiring, ends either shorting to ground or to each other.

I still had all the unused wiring from the ms3x unsecured and just looped up/stuffed away on the engine after fishing for the flex wire to reroute it, so it's more likely something shorted to ground or to another i/o line.

Expensive lesson, I know better.

Peter PM'd me this AM, will be sending it off the coming Friday.
Hope to be driving it today on MS2+ms3x, will just tweak reqfuel for thr E85 for now.
That little $12 ms2x-mini board came in handy.
(it does have a flex input jumper and a little proto perfboard area, looks like that filter could use a zener)

[piledriver]

Root cause found by Peter (after it smoked a second CPU on the bench)
Tiny bit of solder splash under the ribbon cable header on the board.
(will post pics when they arrive, Peter, feel free to post here instead)

[piledriver]

My MS3 has made it home from vacation in sunny Virginia Beach, thank you, Peter!