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-   -   My Quest of Running Flex Fuel on MS3+MS3x (https://www.miataturbo.net/megasquirt-18/my-quest-running-flex-fuel-ms3-ms3x-84634/)

aidandj 07-06-2015 01:47 PM

Haven't gotten to it yet. I got a new oscope (an AWESOME MDO4104), and a lab power supply so I might do some tests sometime. Summer is really busy, fall and winter things will calm down and I can play more.
<br />I saw your posts on MS-Extra, thanks for chiming in here. Did you ever get it working to your liking?<br />I've had some really good experiences working directly with Ken on boost control stuff so I'm hoping it continues.

Braineack 07-06-2015 01:59 PM

aidandj, it sounds like you don't even have an MSLabs built MS3?


my process of setting up flex fuel on my home built MS3+MS3x.
Some of the MSLabs ECU info might just add confusion to you...

aidandj 07-06-2015 02:07 PM

You are correct home built. But its quite similar. Connecting a flex fuel sensor to the ms3 daughter board. Whether its through the ms3x pin, or however rev has it wired its essentially the same process, just a minor setup difference.
<br />
<br />Rev can answer for his ECUs. I've tried to get some info from ms-extra for the ms3x's out there.

Braineack 07-06-2015 02:48 PM

Putting the flex fuel sensor signal directly into FLEX through the expander card, without any modification, is much different that adding resistors directly onto the ms3 cpu daughterboard.

aidandj 07-06-2015 02:51 PM

But the sensor setup, and software setup are the same. So some of that crosses over. I have been told to wire straight to the ms3x flex input. But the details on what that provides are sparse. If I understood right its a direct connection to the ecu pin.

Braineack 07-06-2015 03:05 PM

FLEX goes directly from the Expander to JP2 pin-2 on the MS3 daughterboard.

IIRC there's already 10K resistor in series before the CPU and a 10K pull-up resistor to 5v both on the Ms3 daughterboard on the underside. I can confirm this today if you'd like.

patsmx5 07-06-2015 03:07 PM


Originally Posted by aidandj (Post 1246866)
Haven't gotten to it yet. I got a new oscope (an AWESOME MDO4104), and a lab power supply so I might do some tests sometime. Summer is really busy, fall and winter things will calm down and I can play more.
<br />I saw your posts on MS-Extra, thanks for chiming in here. Did you ever get it working to your liking?<br />I've had some really good experiences working directly with Ken on boost control stuff so I'm hoping it continues.

Well +1 for you doing this and posting how you did it and making it work. So I can copy it. :)

aidandj 07-06-2015 03:28 PM


Originally Posted by Braineack (Post 1246892)
FLEX goes directly from the Expander to JP2 pin-2 on the MS3 daughterboard.<br />
<br /><br />
<br />IIRC there's already 10K resistor in series before the CPU and a 10K pull-up resistor to 5v both on the Ms3 daughterboard on the underside. I can confirm this today if you'd like.

<br />
<br /><br />
<br />Confirmation would save me some time. Please do.

Braineack 07-06-2015 06:13 PM

confirmed.

the FLEX input on JP2 goes through R14 on the bottom of the board before going to the CPU. This is a 10K resistor.

A 10K pull goes to VCC through R3 on the top of the board.

So all anyone with a MS3x needs to do is wiring the Flex sensor into the FLEX input -- MS3X-5.

If you don't have an expander board, but still want to do Flex fuel without lots of mods, just wire your input directly to pin 2 on the JP2 (expansion connector) header.

aidandj 07-06-2015 06:16 PM

Which I believe is what Rev instructs to do. Don't take that as truth though.
<br />
<br />In the past a filter capacitor was discussed. But last I heard on MS-extra this wasn't needed. Not sure what changed.

Schuyler 07-06-2015 06:46 PM

<p>Been busy and missed when you posted this, but it doesn't look like I missed much :P</p><p>&nbsp;</p><p>I'll be watching this like a hawk now though, as I plan on running almost this exact setup (GT500s, DW200 (because not race car), MS3X). I'm adding an aftermarket 1:1 FPR though because I have a '00, but I think that will be about the only difference between the two setups.</p>

aidandj 07-06-2015 06:56 PM

Lol. I'm adding a fuel lab afpr and bumping to 60psi too.

Schuyler 07-06-2015 07:02 PM

<p>Oh that's right, you bought Ben's.</p>

aidandj 12-21-2015 12:28 PM

Bringing this back up. I am ordering up all the final parts for my fuel system. And am missing 2 things.

I want some really good e85 resistant rubber line. (LAPS?)

And if possible a replacement stock filter. I've read that e85 can be harsh on paper filters, and my 190k OEM filter probably isnt in the best condition.

Lincoln Logs 12-21-2015 02:01 PM


Originally Posted by aidandj (Post 1293804)
Bringing this back up. I am ordering up all the final parts for my fuel system. And am missing 2 things.

I want some really good e85 resistant rubber line. (LAPS?)

And if possible a replacement stock filter. I've read that e85 can be harsh on paper filters, and my 190k OEM filter probably isnt in the best condition.

I've been using the bio fuel approved fuel injection line for 3 years running E85 without problems. Just make sure you get the line approved for the higher pressures of a fuel injected car, not the cheap stuff that is only meant for carbs.

Same with the filter, just get the Mazda or Autozone replacement and swap it out after a few tanks of E85.

aidandj 12-21-2015 02:02 PM

Thanks. Eventually I will be AN6 pump to rail, but for now I'm leaving the stock hardline, and the 2 hoses that connect to it.

Lincoln Logs 12-21-2015 02:20 PM


Originally Posted by aidandj (Post 1293829)
Thanks. Eventually I will be AN6 pump to rail, but for now I'm leaving the stock hardline, and the 2 hoses that connect to it.

I've been running those hard lines for a while with 240WHP on E85...there is not an imminent need to replace them.

aidandj 12-21-2015 02:21 PM

Yeah, I know. Thats why I'm not doing it yet.

Schuyler 12-21-2015 02:26 PM


Originally Posted by aidandj (Post 1293804)
Bringing this back up. I am ordering up all the final parts for my fuel system. And am missing 2 things.

I want some really good e85 resistant rubber line. (LAPS?)

And if possible a replacement stock filter. I've read that e85 can be harsh on paper filters, and my 190k OEM filter probably isnt in the best condition.

I'm running this stuff from the AFPR -> Evap hard line for my return.
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aidandj 12-21-2015 02:27 PM

Are you just clamping it on?


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