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Petrovich
Joined: 27 Sep 2005
Posts: 235
Location: Rockville, MD
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 Posted: Thu Dec 01, 2005 11:05 am Post subject: How exactly does DITC work?... |
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While waiting for weekend time to finish the fuel part of Megasquirting my 931, I've been thinking about ignition, and as hard as I was thinking, I couldn't figure out a reason why MSII would not be able to control late model 931's ignition system. I mean, if DITC can do it... IIRC there's a crank angle sensor, so I should be able to get it to work...
Can anyone explain me how the whole system works, or point to a FAQ or something of that sort? I need to know the pinout at DITC box, sensors that are available, and, if at all possible, the type of output that those sensors produce. |
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Khal
Joined: 26 Sep 2003
Posts: 4872
Location: Sunny and lovely interior BC, Canada
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| Posted: Thu Dec 01, 2005 11:14 am Post subject: |
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The DITC has a vacuum line going to it, IIRC (?)
Perhaps MSII doesn't have that?
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'80 924 Turbo |
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Petrovich
Joined: 27 Sep 2005
Posts: 235
Location: Rockville, MD
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| Posted: Thu Dec 01, 2005 11:31 am Post subject: |
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No, MSIIis pretty much designed around a MAP sensor, so no problems there... I have no problems reading vacuum, throttle position or intake air temperature; what I am more worried about is the crank angle.
Would I correctly understand that 931's crank sensor is a Variable Reluctor type? |
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John Brown
Joined: 07 Nov 2002
Posts: 903
Location: Leesburg VA
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| Posted: Thu Dec 01, 2005 1:31 pm Post subject: |
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| Petrovich wrote: | No, MSIIis pretty much designed around a MAP sensor, so no problems there... I have no problems reading vacuum, throttle position or intake air temperature; what I am more worried about is the crank angle.
Would I correctly understand that 931's crank sensor is a Variable Reluctor type? |
There are (100 I think) extra added teeth on the flywheel. One 'missing' tooth for sync. The sensor is a single coil. Manifold pressure is run to the box which contains a MAP. And intake temp is from a sensor ahead of the throttle body. That's really about it. The throttle sensors are 3 micro switches and I believe no rate information is taken, only position.
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John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82 |
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Petrovich
Joined: 27 Sep 2005
Posts: 235
Location: Rockville, MD
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| Posted: Thu Dec 01, 2005 2:21 pm Post subject: |
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| Hold on, so you're telling me, I can throw the DITC out the door, and install Megasquirt as plug'n'play? 'cause V3 board not only supports VR sensors, but it can also drive ignition coil directly... |
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Darin81T
Joined: 03 Sep 2003
Posts: 124
Location: Vader, WA
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| Posted: Thu Dec 01, 2005 3:38 pm Post subject: |
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| I'm pretty sure the 931 has a Hall sensor, not a VR sensor. |
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Petrovich
Joined: 27 Sep 2005
Posts: 235
Location: Rockville, MD
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| Posted: Thu Dec 01, 2005 4:42 pm Post subject: |
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| What kind of output would I get from it then? I really, really hope it's a pulse/revolution, otherwise I'm doomed to doing some programming... |
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John Brown
Joined: 07 Nov 2002
Posts: 903
Location: Leesburg VA
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| Posted: Sat Dec 03, 2005 3:39 am Post subject: |
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| Darin81T wrote: | | I'm pretty sure the 931 has a Hall sensor, not a VR sensor. |
The '80 has a hall sensor (in the distributor). '81 and later using the digital system off the flywheel teeth uses a coil sensor. The output is a sine which is monitored by the box under the heater core. No hall sensor on the digital system.
The trick is does the Megasquirt have sufficient flexibility to work with 100 pulse/rev with a 'missing' pulse for reference? And, the factory system uses the distributor to select the correct plug.
_________________
John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82 |
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Darin81T
Joined: 03 Sep 2003
Posts: 124
Location: Vader, WA
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| Posted: Tue Dec 06, 2005 3:19 am Post subject: |
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| John Brown wrote: | '81 and later using the digital system off the flywheel teeth uses a coil sensor.
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Which is a Hall Sensor |
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endwrench
Joined: 07 Dec 2002
Posts: 1631
Location: Victor, Montana
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| Posted: Tue Dec 06, 2005 6:46 am Post subject: |
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The MS-II with V-3 board will read a a hall effect switch but you cannot use the 100-1 tooth wheel as a reference because you need a wheel decoder that is not yet available with MS-II. It probably will be sometime in the next 3-6 months if you want to wait. If not your best bet would be to just use the signal from the distributor mounted halleffect (assuming it gives 2 pulses per crank revolution) and mount a VB921 to your bourd for direct control of the coil. You would need to lock the distributor for this if it is not already.
Todd |
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924 FAQ (Technical)
