My Quest of Running Flex Fuel on MS3+MS3x
 

<p>This has been touched upon recently in a couple other threads so I am going to make a central thread where I document my process of setting up flex fuel on my home built MS3+MS3x. The process should be quite similar on MS3Pro, and MSLabs MS3s. You peasants with MS2's I can't help you. The goal is that by the end of this I will have a shopping list that anyone can go purchase and run flex fuel with their megasquirt.</p><p>Parts I've acquired so far if you want to follow along:</p><p>GT500 600cc injectors</p><p>DW200 Fuel Pump</p><p>GM Flex Fuel sensor&nbsp;(there are multiple to choose from, see this link for more info about the current cheap ones)</p><p>Sensor Harness</p><p>Ricey Badge&nbsp;(Optional)</p><p>I have done quite a bit of reading, and have contacted DIY autotune for some base maps. As far as I can tell I'm going to wire the flex fuel sensor into the Flex Input on my MS3x and then that should give me ethanol percentage. Everything after that is going to be tuning, and I will figure that out in the future.</p><p>Two Miatas that I have seen mentioned running flex fuel are <span>@AbeFM and DIYs Miata,&nbsp;</span><span>@Matt Cramer and <span>@Ben, any input is greatly appreciated. Attached is the basemap that DIY sent me from their miata running flex fuel.</span></span></p><p>&nbsp;</p>

Awesome will be watching this and asking dumb questions.

<p></p><p>As will I.</p>

https://www.miataturbo.net/attachmen...ine=1436205463

This is what Demitrios provided for the addition of flex sensor to ms3 basic. Just throwing it in the bowl, if its not common.
...

The flex input should already have a pull up on the ms3 card. I need to go read again.

This went with the picture, might help...

"This is what you need to do to enable Flex Fuel.
The port to use for flex fuel with this modification done is "PE0".

--
Dimitris Stasinopoulos
MS Labs - Automotive Electronic Solutions"

That makes sense. PE0 is a different pin than Flex.

Wait. It might be the same. Damn I wish the schematics were open source.

In4dumbquestions.

Also, nice choice of injectors :party:

Had to throw in a shout out.

Flex fuel compatability became a standard feature on the MS3 Basic at some point. I know all the boxes I've sold have had it set up as standard (i.e. no internal mods required).

My unit is an early 2014 and needs the internal mod from talking to Demitrios. Im looking forward to this flex sensor build but i'm holding off adding e85 until my motor is built, when the DP goes on i will already be close to the rods torque safety limit.

<p><span>@Reverant could you clarify when it became a standard feature and what the wiring is to PE0?</span></p>

01-05: 3.0c and higher
99-00: 3.1 and higher
96-97: 3.1 and higher
94-95: 3.0a and higher
90-93: 3.0a and higher

The suggested modification above means that you will need to connect the 2 resistors to the sensor and the MS3 board as shown, then route the wire to the ECU through any unused pin on the DB37.

What is the point of the resistors.

To make it work. :)

Yes but why, I thought the ms3 card had built in pull up resistors on the flex input.

The FLEX input on the earlier boxes was used for the VSS input instead. So instead of using the FLEX input for flex fuel, PE0 is used instead, and that one doesn't have the resistors.

Awesome.

How'd it go? I had lots of issues early on, something in the code would lose count, and it'd think my fuel temp was -40* C or something ridiculous. Anyway, it would go full rich to compensate just once in a while, whole car bucked. I complained, I assume some smoothing was done in software. Worth being aware of. :-)

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.

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

Some of the MSLabs ECU info might just add confusion to you...

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.

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.

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.

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.

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

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

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.

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.

<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>

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

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

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.

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.

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

I'm running this stuff from the AFPR -> Evap hard line for my return.
Summit Racing® PTFE Hose SUM-220984 - Free Shipping on Orders Over $99 at Summit Racing

Are you just clamping it on?

@ Evap Line

@ Fuel rail
(Hose clamp -> oem NA FPR)

Everything @ AFPR
Fragola Performance Systems Real Street Reusable P.T.F.E. Hose Ends 680106-BL - Free Shipping on Orders Over $99 at Summit Racing

@ The tank (+ hose clamps)

Yeah. I have all that.

I'm just going to hose clamp onto my NA rail for now. Eventually I will do bulkhead fittings at the tank and all that jazz.

I lost the NA sender I bought :| I'm going to have to find another one now... meh.

NA FPR? Or in tank.

NA FPR. I'm running the DW200 with the in-tank NB FPR right now, but E85 will need moar fuel.

I'll sell you mine for cheapsies

Aidan, how's this coming along? Did you get the car running on the flex sensor?

Assuming I'm understanding the MS3 software it looks like you can handle E85 with the old "add x fuel, add x timing" method that MS2 used, or you can set up 2 entirely different tunes and let it interpolate between the two. I assume the best way to handle it is to just zero out the fuel/timing add and create 2 tunes?

If you set it up with 2 maps, does analyze live or megalog viewer take the dual fuel maps into account when adjusting the tunes?

I never did. It's all on my shelf. Ben did though.

The best way to do it is to run straight e85 and autotune that for table 3, and then blend with table one. Do the same with soark.

The blending is a science. Theoretically you can blend 1-1 but I've heard that people who know a lot mor e than me pull a bunch of timing and fuel as soon as the e85 percentage dtops, and then make it more linear. We really need that agrx7 guy, he was an OEM calibration engineer or something. I'll try and tag him later.

Sorry, not much to add to this conversation save for that I'll be implementing this come early summer. Bookmarking this for reference later! Super stoked for easy power gains.

To add some information after doing some looking around MSExtra. VEAL will not work with blend tables on. It may function, but it'll likely tune the VE1 no matter what. The best thing to do is add a tableswitch switch, and tune each individually. The steps would be:

-Note ethanol percentage for E0-10, run VEAL on VE1
-Fill with E85, note ethanol percentage, switch tableswitch to VE3, run VEAL on VE3 (go to VEAL tab, then the third tab will be VE3)
-Set base percentage to your E0-10 ethanol percentage (this tells MS that you didn't tune VE1 on E0, and to set the base of the blend curve at that %)
-Create blend curve with 100% being whatever your ~E85 % was

I've heard the opposite, Aidan. I've heard that E60-70ish behaves very similarly to E85 and doesn't need much timing pulled. Shown in this graph below:

https://www.miataturbo.net/attachmen...ine=1461075629

I'll see if my Dad has any good info or documentation on this. He's been doing alternative energy engineering for 20+ years.

I'll hopefully get my flex fuel sensor in within the next few weeks so I can add first hand information.

Awesome. Looking forward to some sources from a real enginear.

I haven't gone through enough fuel to test my theory, but I ended up leaving my blend curve linear. If you are to have a steep drop off in the curve you're fuel map is going to run lean anytime you're just below the E85 threshold. Since E85 is typically not tuned to the knock threshold anyway and E10 is, I assume that any fuel blend above your base (E10) tune should be safer than the base blend.

Linear fuel makes sense. The steep drop off would be in timing.

If I remember right, when flex blend is enabled, there is only one curve? Because yes, I would think fuel would be linear for energy content, but spark would be different because of RON/ethanol curve.

In ms3 there are a lot of different curves. Spark, fuel, boost, even AFR targets I think. There are different ways of using them. I'll post some screenshots in a bit.

Yeah, for some reason I remembered switching blend curve on, and all the individual blend curves become active (spk, fuel, afr, boost), but when changing a drop down to flex blend, it grays out all of those, and activates one blend curve. I'll have to play around with it more tonight. Reading through the manuals makes it seems like what I just said is not true at all.

I think you might be right. I can't get the spark/fuel to blend separately. Might post on msextra later today.

https://www.diyautotune.com/download...pro_manual.pdf

Good table blending info

I figured out how to do it. You turn on fuel table/spark table switching, and then use a blend curve to combine them.

The blend curve can be based off of ethanol percentage. This gives you the ability to do different blends for different parameters.

https://www.miataturbo.net/attachmen...ine=1461081018

Ahhh, that makes sense, thanks! I believe it's when you turn on "dual fuel" and select "flex" that it only allows one blend curve, I think 'blend curve 8'.