what happens when you measure between pins 2 and 3? and when you measure pins 1 and 3
im sorry but i am lacking the necessary wiring diagrams to help you hear. But i used the tach output from the mac11 to feed the megasquirt board.
regarding the coil... i do not know what could be keeping the coil grounded, however if the coil is hot to the touch, AND your not getting any voltage at the pins for the distributor maybe you popped the ecu? check the ecu fuse in the fusebox and verify please.
if the fuse is ok, then I recommend you check other ecu supplied voltages, such as the throttle switches, and the 02 sensor input and the thermosensor (not the temperature sensor for the gauge!)
if you have a spare mac11 id suggest swapping it but thats risky until you determine what killed the mac11 if its dead.
MY advice. If you did pop the mac11 then it might be wise to switch to megasquirt and spark however there is alot of work to be done for that swap. you need a 5 window hall ring (maybe one from a repair kit instead of risking ruining it taking it out of another distributor), a distributor with locked timing. an LED test light, a 5k resistor to act as a pullup resistor for the hall sensor signal at the megasquirt, and then to verify your running the megasquirt n spark code.
Also you need an ignition driver if you want to keep things simple. an MSD or a Crane cams or even a factory vw/audi ignition driver is fine. The driver needs to be wired to megasquirt and then to the coil (duh). This makes life simple since megasquirt tells the unit when to fire, but the driver controls the coil dwell and power regulation ect... You can connect the coil directly to megasquirt through the ignition driver fet, however you will need to then program and tune the correct dwell for the car to run properly.
I say if you care about the car throw a cheap high power driver on there, makes life easy and you can net multi spark discharge, and other benifits.
after that
basically you need to set the engine to TDC install the distributor so cylinder 1 fires at correct phasing (generally 40-60 deg btdc) and then adjust the static timing and offset using a timing light and megasquirt. once the static timing is set, you can program the timing map and variables.
im pretty good with electronics, and pretty good with cars, and the whole job took me about 4 hours for just the distributor modifications, install, and setup of megasquirt. another hour of tuning and I had a reasonable ignition map.
The thing i hate most about the install... the distributor jitter.... if you do not modify the distributor and knock out all the free play you have a bit of jitter. about 2-3 degrees.
the things i regret? loss of boost control from the mac11, along with emission drive... im talking about the evap canister purge, thats actually useful and does not cost any horsepower at all, and you get better economy because of it. that along with knock control from the mac11. slightly dampened knock control but really effective.
things i like the most is the adjustability of the timing and ability to run very advanced ignition during cruise and idle. nets you alot more torque and smoother idle. and you can even have the timing retarded with a very cold engine to promote faster warmup.
the megasquirts knock control is ok... but at the time i never got the boost control to work properly with the stock audi valve ect... so i left it off.
