lsdweb
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| posted on 11/3/06 at 04:11 PM |
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Crank trigger wheel patterns - Megasquirt
Hi All
I'm planning on running my R1 engine on my Emerald system - this hasn't been done before and there may be a complication with the R1 crank
trigger wheel - picture here.
As a backup, I'm considering going to Megasquirt, but can't find any info on the type of crank trigger wheels compatable with
Megasquirt.
Anybody got any ideas? I also can't find if anybody has used Megasuirt on an R1 (Searching for Megasquirt and R1 gives just about every
megasquirt site that discusses the resistors used!
Regards
Wyn
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BKLOCO
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| posted on 11/3/06 at 04:54 PM |
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For MS you need the standard ford trigger pattern of 36 teeth -1
In other words one of the 36 teeth missing to give a longer pulse to determine TDC.
Experience is what you get when you don't get what you want!!! 
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Rob Lane
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| posted on 11/3/06 at 06:47 PM |
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MS will run on quite a few patterns, 4:1 12:1 24:1 etc.
Looking at that pic, it uses a hall effect sensor with that wheel. The pic looks like a symmetrical wheel with one tooth longer. Could you file it to
form 4 equal points ?
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lsdweb
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| posted on 12/3/06 at 09:51 AM |
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Thanks guys
If I have to use a standard Ford 36/1 wheel I’ll stick with the Emerald system!
If I can use a different pattern with the existing wheel I’ll consider the Megasquirt. If, however, I have a symmetric pattern wheel, how does the EMS
know exact engine position? I’d need a cam position sensor as well and I don’t think the R1 has that!
Nothing is ever simple!
Regards
Wyn
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Rob Lane
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| posted on 12/3/06 at 10:53 AM |
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From the MSnSE manual :-
quote:
MegaSquirtNSpark single coil distributor mode
MSnS (distributor) mode allows you to control your timing if you have a single coil firing a distributor.
Your tach/rpm signal into the Megasquirt can come from a crank trigger or from a "locked" ditributor using hall, inductive VR or opto
sensors.
The code requires ONE trigger per spark event. If you have a multi-toothed wheel such as 36-1, 60-2 or a Nippondenso 24/2 CAS then you need to look at
the wheel decoder instead.
A locked distributor is one that has mechanical and vacuum advance either removed or "locked" out so that the trigger signal occurs at the
same crankshaft angle at all rpms. Many distributor cars with EFI already have a locked dizzy.
Crank triggering provides a more stable advance as there is no timing chain or belt and distributor gear jitter. For a four cylinder engine you would
require two pips/lobes or bolt heads at 180 degrees to each other and a VR sensor. The V3 circuit board can directly read from the VR sensor. The V3
board also provides a VB921 high current driver that will drive your single coil directly. If you use a crank trigger you do not need to modify your
distributor. Just make sure the rotor points towards one of the towers - if it is halfway you can easily get cross-firing.
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lsdweb
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| posted on 12/3/06 at 09:30 PM |
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Thanks Rob
I think I understand! But how does the EMS know where the engine is in the cycle if the two lobes are the same?
Wyn
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stevebubs
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| posted on 13/3/06 at 09:41 PM |
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There's normally a secondary trigger from somewhere to indicate TDC or similar.
S
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stevebubs
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| posted on 13/3/06 at 09:45 PM |
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http://megasquirt.sourceforge.net/extra/
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stevebubs
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| posted on 13/3/06 at 09:51 PM |
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quote:
Originally posted by stevebubs
Wyn,
Think your simplest option would be to get a 4-1 or 8-1 wheel made up to replace the existing one. This should be do-able in the amount of space you
have.
See Here
Stephen
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lsdweb
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| posted on 13/3/06 at 10:07 PM |
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Thanks Guys
Info much appreciated. I'm optimistic that Emerald can provide a solution. I spoke to Dave Walker today - they've got my ECU and the R1
trigger wheel so I'm just waiting for a phone call to say they can do it.
If not, I'll have to start doing some serious research into MS or looking at another ECU like DTA.
Regards
Wyn
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liam.mccaffrey
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| posted on 14/3/06 at 12:14 AM |
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I decided to go MS in the end wyn, I will let you know how it goes, I'm getting wideband kit with it too!
Build Blog
Build Photo Album
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lsdweb
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| posted on 14/3/06 at 08:39 AM |
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Hi Liam
I saw your post - are you building the MS yourself or getting it ready made? I wouldn't have the guts to try and build it myself - my electrical
work is good but I don't understand electronics enough (at all!) to understand what I'd be doing!!
If I do end up going the MS route I'll have to buy a ready made ECU. This will be more expensive but a lot quicker!
How's the rest of the car build and the house build coming on?
Regards
Wyn
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liam.mccaffrey
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| posted on 14/3/06 at 05:12 PM |
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I'm not building it myself, but i reckon i could I did A-level electronics which was pretty hands on. maybe bext time!
Bill Shurvington is providing mine
The house is slow we are chasing the architect, we still haven't applied for planning yet
but on the bright side car is about to take off quickly, idecided to make a front suspension jig before i made the chassis as neither the chassis nor
the wishbones were "book" . This was to ensure i didn't fupp up the front of the chassis. I hope it works well it should as
i'm building around correct suspension geometry
Build Blog
Build Photo Album
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