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Thread: AdmiralSenn (Adam S.) #3416 "Christine" Megasquirt conversion

  1. #11
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

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    My VIN:    03572

    If I were to try EFI, I think I would get compleat 3.0 even fire and work on it mounted on a test stand. It's such a big project it is at the end of my to do list.

    I've been thinking about another project for quite some time but have to keep this also on the back burner. That is a new ignition ECU that lets you adjust ignition timing on the fly. So you would set your ignition timeing at 20 deg. and it would delay each fire to let you adjust it to any value less the 20.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  2. #12
    Back to the Omnipresent! Spittybug's Avatar
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    Owen, I'm not yet doing ignition control, just fiddling with the mechanical dizzy still. I'll be doing that map after fuel makes some kind of sense. Either way the advance numbers should be somewhat similar.
    I'm curious as to why you are fiddling with VR pots therefore

    Are you taking your RPM signal from the coil (-) gray/white wire or from the VR signal wire directly out of the dizzy? If you are already taking the VR signal (which it sounds like you must be since you said it "made a marked improvement" to the running of the car, you are mere nanoseconds from running full EFI & spark control! Tack down those weights, disconnect the vacuum hose and run the advance table.
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
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  3. #13
    Back to the Omnipresent! Spittybug's Avatar
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    Quote Originally Posted by nullset View Post
    Are you using the engine from the 3.0L PRV?

    I have one of these sitting around, and am very interested in doing the swap.

    Perhaps we can bring back the "3.0 swap and support" thread?

    --buddy
    Why don't you bite the bullet and start such a thread as if it were an EFI conversion? Just name it something like "Nullset's 3.0L PRV conversion". It doesn't have to be a real project, but who knows, it may turn into one!
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
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  4. #14
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

    Posts:    1,720

    My VIN:    01049

    Quote Originally Posted by Spittybug View Post
    I'm curious as to why you are fiddling with VR pots therefore

    Are you taking your RPM signal from the coil (-) gray/white wire or from the VR signal wire directly out of the dizzy? If you are already taking the VR signal (which it sounds like you must be since you said it "made a marked improvement" to the running of the car, you are mere nanoseconds from running full EFI & spark control! Tack down those weights, disconnect the vacuum hose and run the advance table.
    I apologize for sort of highjacking this thread, but since I plan on spark control AFTER I get fueling going, I'd like to understand how this works a little better.

    So the weights get tacked down, the vacuum hose disconnected. So the MS ECU gets the tach signal straight from the VR wire so I understand how it knows what the RPMs are.

    What I'm not understanding is how MS actually controls the timing at this point. How is it actually telling the system when to fire?
    -Mike
    1981 DeLorean, heads/cams/exhaust, EFI
    1999 Corvette, heads/cam/exhaust, 440 BHP
    2005 Elise, stock
    2016 Chevy Cruze

  5. #15
    Back to the Omnipresent! Spittybug's Avatar
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    Quote Originally Posted by opethmike View Post
    I apologize for sort of highjacking this thread, but since I plan on spark control AFTER I get fueling going, I'd like to understand how this works a little better.

    So the weights get tacked down, the vacuum hose disconnected. So the MS ECU gets the tach signal straight from the VR wire so I understand how it knows what the RPMs are.

    What I'm not understanding is how MS actually controls the timing at this point. How is it actually telling the system when to fire?
    In MS you have an advance table in which you tell it what degree of advance at what RPM/load combo. Just like the VR signal from the dizzy tells the ignition controller when to send coil pulse, it does the same for MS who sends the signal to the coil instead. As part of the MS build there was the choice to build the input circuits: Hall/optical or VR. Usually you just build both and choose with jumpers. Later in the build you had a choice to build the high current ignition driver circuit to drive a single coil. This basically does what the stock ignition box does but with the added ability to play with the timing digitally, rather than letting vacuum and centrifugal forces do it. If one wished to drive multiple coils then there are a few additional circuits that must be built on the board, but it isn't too bad. The problem lies in the fact that we are odd fire and therefore must provide the logic module with information on both the cam and crank positions so that it knows when we're on the power stroke. In a "wasted spark" setup (even fire only), we can just tell the unit to send spark at every TDC event. Half of the time it is sparking in a cylinder that has exhaust valves open, but who cares; hence the term wasted spark. On an even fire engine, there is a cylinder that is on its power stroke at the same time, but not for us odd fires. I'll see if we can add more info in the EFI documentation sticky.
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
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  6. #16
    Senior Member AdmiralSenn's Avatar
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    I believe MS actually just grounds the coil to fire it at the appropriate point. Pin 36 on the DB37, just tap it into the white/slate wire.

    Owen, I agree that I'm close, but I lack the ability to tack anything down since I don't have access to any sort of welding equipment. I'm also super reluctant to do anything to my distributor without a spare handy - having gone without driving Christine for more than a year as it is, I don't want to risk a longer wait just as I'm about to get her on the road again. Removing that last ECU is on my to-do list, especially since I need the ability to retard ignition once I start playing with the nitrous. Find me a broken distributor to have welded and I'll do it tomorrow!

    I have no idea why the VR pots were that far out of adjustment as I don't normally touch them - I just figured I'd make sure this time and lo and behold, they were all screwy.

    And I'm still happily taking my VR signal off the distributor directly. I think I might have been the first person to try that, actually...
    Aka Adam S, aka Adam Wright
    1981 DMC-12 #3416, mothballed in preparation for motor swap
    2006 Volvo S60R

  7. #17
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

    Posts:    1,720

    My VIN:    01049

    Appreciate the education, Owen. So, for example, on my car if I wanted to go ignition control, I would tack down the distributor weights, get the tach input straight from the VR wire, set the appropriate settings in Tuner studio.

    And to get MS to then tell the coil when to fire I run a wire(s) from the ECU (in my case, relay board) to the ignition coil....?
    -Mike
    1981 DeLorean, heads/cams/exhaust, EFI
    1999 Corvette, heads/cam/exhaust, 440 BHP
    2005 Elise, stock
    2016 Chevy Cruze

  8. #18
    Back to the Omnipresent! Spittybug's Avatar
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    Location:  Hot and bloody humid Houston

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    Adam & Mike;
    Yes, the MS is just a switched ground from the coil. (same net effect, right? All we are doing is controlling when to break the primary circuit so that the induced voltage goes high on the secondary coil... thus a spark that gets distributed)

    Rather than tacking, perhaps something so deliciously low tech and reversible as a couple of twisty ties to secure the arms in place? Hell, just wrap thread around them! Remember, all you need to do is stop the arms from swinging outwards with centrifugal force.

    I think I might have been the first person to try that, actually...
    I'm taking signal straight from VR, so sorry, you aren't unique!

    Mike, Pin #36 goes straight to your coil (or just tap it into the slate/white which goes to the coil). MS does the rest so long as it is getting the VR signal from the dizzy and you have the right parameters set (see my .msq in my project).
    Owen
    Tour the country and visit breweries through the eyes of our two puppy dogs. http://www.twobrewdogs.com
    Help us spread the word! @twobrewdogs on Twitter, twobrewdogs on Facebook.

  9. #19
    Not a DeLorean Guru
    Join Date:  May 2011

    Location:  Rochester, NY

    Posts:    1,720

    My VIN:    01049

    Quote Originally Posted by Spittybug View Post
    Adam & Mike;
    Yes, the MS is just a switched ground from the coil. (same net effect, right? All we are doing is controlling when to break the primary circuit so that the induced voltage goes high on the secondary coil... thus a spark that gets distributed)

    Rather than tacking, perhaps something so deliciously low tech and reversible as a couple of twisty ties to secure the arms in place? Hell, just wrap thread around them! Remember, all you need to do is stop the arms from swinging outwards with centrifugal force.

    I'm taking signal straight from VR, so sorry, you aren't unique!

    Mike, Pin #36 goes straight to your coil (or just tap it into the slate/white which goes to the coil). MS does the rest so long as it is getting the VR signal from the dizzy and you have the right parameters set (see my .msq in my project).
    Starting to make more sense. Right now, I run a shielded wire from the tach wiring port on the relay board to the negative post of the coil. So, for ignition control, I would have to remove the shielded wire from the negative post of the coil and instead tap it into the gray/slate wire, correct?
    -Mike
    1981 DeLorean, heads/cams/exhaust, EFI
    1999 Corvette, heads/cam/exhaust, 440 BHP
    2005 Elise, stock
    2016 Chevy Cruze

  10. #20
    Senior Member AdmiralSenn's Avatar
    Join Date:  May 2011

    Posts:    432

    Quote Originally Posted by opethmike View Post
    Starting to make more sense. Right now, I run a shielded wire from the tach wiring port on the relay board to the negative post of the coil. So, for ignition control, I would have to remove the shielded wire from the negative post of the coil and instead tap it into the gray/slate wire, correct?
    Not exactly. The shielded wire is your tach input. Gray/slate is the same wire as coil negative. For full spark control you'd tap the shielded wire into your VR wires from the distributor, and run pin 36 to the gray/slate (or direct to the coil).

    Owen, I know you're running VR too. I just remember feeling like I was nuts, being the only one who did it that way. It was so long ago, though, I don't really remember. I vaguely remember advising somebody on it during their conversion, maybe it was yours - it was on the .com site.

    Anyway, it doesn't matter who came up with it, I don't know why I even mentioned it. >_<

    Any piercing insights into my hunting problem? I'll log on from the laptop shortly and upload the log.
    Last edited by AdmiralSenn; 11-02-2011 at 03:46 PM.
    Aka Adam S, aka Adam Wright
    1981 DMC-12 #3416, mothballed in preparation for motor swap
    2006 Volvo S60R

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