Reluctor and rotor phasing / MS2 setup

[Philip Lochner]

Dear chaps
 
I intend fitting my MS2 into my LR Discovery but initially I want it to handle ignition advance only.  (The car already has an ECU that does FI so I want to get ignition right first before I take control of the FI eventually)
 
I will have a VR input from a "fully locked" or "fixed timing" distributor (ie no vac or centrifugal advance) to the MS2 which will then fire a TP100 ignition module (I do NOT have IGBT installed - wanted to keep the MS2 more "generic").  The TP100 fires the coil when the TP100 input signal goes to ground based on the ignition advance map in the MS2.
 
Somehow it is still not clear to me how to set up the MS2, the reluctor and the rotor. So, here's what I THINK I should do, but I would appreciate your corrections / comments.
 
It is in particular steps 6 and 7 that I'm not too sure about.  Also, how does the "trigger offset" window (with the large figure and the small adjustable figure with the + and -) relate to the steps below?
 
1) With engine @ 22 deg BTDC on cyl1 compression stroke turn the distributor body so that rotor is facing directly to cyl1 terminal and lock the body in position (22 deg is more or less halfway between the most retarded and most advanced points);
2) With engine @ 6deg BTDC in cyl1 compression stroke, set the reluctor on the distributor shaft so that a reluctor trigger to directly face the pickup and lock it in position. (do not change the position of the distributor body);
3) Connect the VR output to the MS2 such that a negative going transition will occur when the reluctor trigger passes the pickup (check with oscilloscope if possible);
3) With Megatune set "trigger offset" under "Ignition options" to +6 (this figure or the physical reluctor position may have to change slightly) when confirming with the timing light;
4) Set Ignition input capture to "Rising edge"
5) Set cranking trigger to "trigger rise" (this will affect ignition to occur at 6 deg BTDC regardless of rpm changes during cranking);
6) Set "coil charging scheme" to "EDIS" (see step 7)
7) Set "spark output" to "going low".  This is when the TP100 will be triggered and when spark is generated. (from the manual I get that if no transistor (IGBT??) is used on the output, the coil charging scheme needs to be "reversed" - which I presume is then why "coil charging scheme" needs to be "EDIS")
 
I THINK I'm OK with the rest of the settings but I would like to have some degree of confidence that I'm on the right track (otherwise my neighbour WILL complain about all my false starting attempts....)
 
 
Kind regards
Philip Lochner
 

Posted by email.

[Bernard Fife]

Philip,

I think that's right (and a very nice description of the process, btw!) except the last two points.

Don't set the Coil Charging Scheme to EDIS, this gives a completely different signal (whose pulse width is a function only of the advance). Set it to 'Standard Coil' Charge' instead.

Then you need to get the Spark Output right. You want to spark when the signal goes low. Oddly, this means you have to set spark output to 'going high (inverted)'. This is because the terminology was based on the beta MS-II which had a transistor (not the IGBT) in the ignition output that inverted the output (so 'going low' was actually 'going low'). However, to make room for the CAN chip, this transistor was removed from production versions of MS-II, this reversed the meaning of the two labels, and the terminology was never changed. So you need to set it to 'going high (inverted).

Lance.

[Philip Lochner]

Thanks Lance!
 
Greatly appreciate the comments.
 
 
Kind regards
Philip Lochner

-----Original Message-----
From: lance [mailto:megasquirt@shaw.ca]
Sent: 28 February 2006 05:41 PM
To: megasquirt2@msefi.com
Subject: Reluctor and rotor phasing / MS2 setup



Phillip,

I think that's right (and a very nice description of the process, btw!) except the last two points.

Don't set the Coil Charging Scheme to EDIS, this gives a completely different signal (whose pulse width is a function only of the advance). Set it to 'Standard Coil' Charge' instead.

Then you need to get the Spark Output right. You want to spark when the signal goes low. Oddly, this means you have to set spark output to 'going high (inverted)'. This is because the terminology was based on the beta MS-II which had a transistor (not the IGBT) in the ignition output that inverted the output (so 'going low' was actually 'going low'). However, to make room for the CAN chip, this transistor was removed from production versions of MS-II, this reversed the meaning of the two labels, and the terminology was never changed. So you need to set it to 'going high (inverted).

Lance.



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Posted by email.