Curious if anyone knows what the trigger voltage to the leading coil shoul be? Or if you could try it out on your own car. When I say trigger voltage I'm asking about the voltage between the tan wire on the coil and a ground. Thanks

 

Is this on 2nd gen coils, or the 1st gen coil & distributor? Taking a guess, I doubt there will be any voltage on the car thats not 12v (unless you've retrofitted a Lucas Electrics system... and noone would do that). The coil should be supplied with constant 12v (as long as the car is on), and the MS will switch ground to it. The coil dwell is the amount of time the MS grounds the trigger wire, and as soon as the ground is removed, the coil discharges.

At least for the S4 coils, i see a black/yellow (const 12v) and grey/yellow (trigger, ~0.8v @ idle) on the leading.

Just in case, there are 2 black/yellow's (12v), a brown/yellow (trailing switching signal, ~2.2-4.4v), a blue/yellow (trailing trigger, ~0.8v @ idle), a blue/red (trailing timing, shouldnt be used w/MS IIRC), and a yellow one (goes to tach).

All these voltages are out of the FSM, i havent checked them myself.

 

alright so my numbers appear to be right, but not getting any spark.

 

Are you getting constant 12v on the other wire? is the dwell set too low (or too high and you've toasted the coils?) Did the coils work in an otherwise working setup? have you re-seated the plug wires, cleaning off the contacts and maybe using a little dielectric grease? Are the plugs new/good condition/not worn?

Just a couple things that come to mind.

 

I am getting a constant 12v to the other side, not too sure about the dwell setting. What are they suppose to be set at?

 

3-4ms when running, a little bit higher (~6ms or so) when starting. I dont remember what its set at in my setup right now, those are just samples taken from the MS-extra manual

 

The coil should be supplied with +12v on its power wire, and the signal wire from the MS should have a +5v square wave on it.

Measuring with a volt meter, the +12v wire should be at +12v (higher while running), and the signal wire should be anywhere between < 1 volt and ~4 volts depending on rpm and dwell.

Ken

 

hmm so min 1 volt eh ... i'll be looking to see where the drop is. Thanks