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What is needed for megasquirt?

Posted by Brad Bell, Sep 18, 2020

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  1. Brad Bell

    Brad Bell Proven Member

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    Levant, Maine
    I have been running a fmu/stock ecu turbo setup for years now and I am ready for megasquirt. Tired of all the bugs/unreliability and really just want to make the jump from one to the other.

    I'm new to the whole megasquirt/tuning deal but have been doing alot of research the past couple weeks. So I'm asking what specifically is needed other than the unit itself. I'd like to do a complete standalone system pre assembled, I'm thinking a megasquirt 2 assembled unit from diyautotune.com with a 8' standard harness.

    Now to the specific questions I have. Other than the assembled unit and harness, is there anything else I will need to order from diyautotune? Is there any specific mods I have to do to the unit to work correctly? I have read, and seen videos of guys installing megasquirt and they are installing a second coolant and manifold temp sensor, what is the reason for this? Can we not hook up the existing sensors to the ms? Map sensor?

    As for fuel, I am running a begi/cartech rising rate sfmu, and understand I will need a 1:1 rising rate regulator instead if I'm correct? What model works best?

    Thank you
     

    Street Build 639  9

    1999 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  2. dsmcrzy

    dsmcrzy Proven Member

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    The MS2 and 8’ harness will work. Just let them know what you will be using it on so they can do any internal mods when it’s being built.

    I use both the stock coolant temp sensor and manifold air temp sensor. Second coolant temp sensor could be due to them keeping the stock ecu in place. Moving the air temp sensor to the inter cooling piping makes sure the sensor doesn’t get heat soaked like it can in the manifold. I have been meaning to move mine.

    Map sensor is on the main board the the MS unit.

    Any 1:1 rising rate FPR will work. Obviously go with a more name brand unit like aeromotive, fuelab, etc.

    You will also need a wide band air fuel ratio gauge. The output gets sent to the MS unit so it knows what the AFR is.
     

    Street Build 5K  13

    1996 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  3. randman2011

    randman2011 Proven Member

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    Indianapolis, Indiana
    Megasquirt can use pretty much any sensors in existence, but because it is most commonly used on EFI swaps for LSx V8s, the GM style sensors are well documented and come configured by default. To many, swapping sensors is easier than calibrating the existing ones, but its not a big deal. The 4G63 has some pretty decent Megasquirt support these days as well, and I'm considering it for mine because I find it easier to get right than ECMLink, H8 black box, and EVO 8 ECU.

    If your engine harness is in good shape, you can get the DIYPNP N76 which is based on the MS2 and comes with the factory connectors for direct plug and play into the existing harness. No wiring necessary, but you can't get them preassembled.

    DIYAutoTune's website lists the N76 as compatible with all 2g DSMs regardless of engine option, hence my suggestion, but it's entirely possible they don't realize the 420a exists. I don't have any knowledge of the 420a ECU connectors. EDIT: Oh yeah, no. Completely different connectors. In my search for male 420a connectors to make a patch harness (which I did not find) I did find this: http://old.symtechlabs.com/catalog/complete-420aneon-megasquirt-ems-kit-p-57.html but it still lists the LC-1 as the latest EGO, so who knows if it's still an option.

    Edit again. https://www.symtechlabs.com/megasquirt-ems/megasquirt-ems-kits/420a-neon-megasquirt-ems-kit.html Out of stock but potentially worth an email? Still not PnP though. Seems like it's just the normal MS2 stuff plus a 420a alternator voltage regulator, whatever that is supposed to achieve.
     
    Last edited: Sep 18, 2020

    Street Build 1K  1

    1998 Mitsubishi Eclipse GSX
    awd · manual · 2G DSM
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  4. dsmcrzy

    dsmcrzy Proven Member

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    OP has a 420a so that N76 won’t work. Have to do it the hard way on the 420a.
     

    Street Build 5K  13

    1996 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  5. Brad Bell

    Brad Bell Proven Member

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    Levant, Maine
    Thanks for the info guys, I currently have an AEM wideband gauge so I'm guessing the signal wire from the sensor itself will have to be spliced into the megasquirt along with the gauge itself? What about the factory narrowband sensor?
     

    Street Build 639  9

    1999 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  6. dsmcrzy

    dsmcrzy Proven Member

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    If you are leaving the stock ecu in place you can leave the factory sensor in and hooked up. If you are removing the stock ecu then the stock O2 serves no purpose.

    Out of the wide and controlled there should be a 0-5v output. That will be sent to the MS unit via the wideband input. Believe it’s pin #23.
     

    Street Build 5K  13

    1996 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  7. Brad Bell

    Brad Bell Proven Member

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    Levant, Maine
    Perfect, now that you say it I do remember a white output wire coming from the gauge that I didn't use. Well so far it all sounds pretty straight forward, I think my next steps are really just to order the unit and let them know what platform its for in case they need to do any internal mods like you said.
     

    Street Build 639  9

    1999 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  8. dsmcrzy

    dsmcrzy Proven Member

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    If you can solder and follow direction and have the time you could get the disassembled kit and put it together yourself. I built my MS3x like 9 years ago. It was time consuming but a fun process. The manuals are also a lot better setup now.

    You can get a base tune fine from symtech labs repository. just don’t try to order from them. They went defunct years ago. I’m surprised the website is still up to be honest.

    http://old.symtechlabs.com/support/msq_rep.php
     

    Street Build 5K  13

    1996 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  9. motomattx

    motomattx Proven Member

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    wampum, Pennsylvania
    I am currently installing a fully assembled surface mounted MS3 plus in a 420a car, fully replacing the stock ecu, we somehow have a blown daughter board which contains the processor within 5 minutes of trying to start the thing, likely either static damage to the board or factory defect, a few on their forums have had the same problem, there doesnt seem to be much support as far as caring that a $800 purchase is dead after 5 minutes of being installed, that leaves a terrible taste in my mouth, the support in general sucks for this thing if you ask me, I am used to installing the Link G4+ ecu's so I am spoiled on support and lifetime warranty. The daughter board itself is $230 so I am not too happy right now, as it looks like we are sol and I suppose just have to spend that much more to fix a new standalone. If I had known that my buddy was going stand alone I would have had him get the Link unit but he bought this without my knowledge.
     

    Drag Race Build 4K  10  24

    1995 Mitsubishi Eclipse GST
    fwd · manual · 2G DSM
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  10. VelocitàPaola

    VelocitàPaola Moderator

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    Ft. Lauderdale, Florida
    The stock ECU controls the alternator. If you take it out, you need an external regulator.
     

    2K  21

    1995 Mitsubishi Eclipse N/T
    manual · 2G DSM
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  11. Brad Bell

    Brad Bell Proven Member

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    Levant, Maine
    How is this done exactly, any regulator in specific? Thanks Paul
     

    Street Build 639  9

    1999 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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  12. dsmcrzy

    dsmcrzy Proven Member

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    Trenton, Ohio

    Street Build 5K  13

    1996 Mitsubishi Eclipse N/T
    fwd · manual · 2G DSM
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    Brad Bell likes this.
  13. VelocitàPaola

    VelocitàPaola Moderator

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    I can't remember where the idea originally came from, but I think it was from Vortech or a similar company that sold a supercharger kit for the Neon. They suggested using a VR-125 voltage regulator from a late 1980's Dodge Omni. It turns out that works pretty well, so it has been the standard part for the job since then. Any online or brick-and-mortar parts store should have them. There's a connector available for it too.

    Here are installation instructions: https://www.symtechlabs.com/docs/alt_voltage_regulator.pdf
     

    2K  21

    1995 Mitsubishi Eclipse N/T
    manual · 2G DSM
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