MicroSquirt.com read only forum (Jan.15,2018)

I had this post in the MSII section and didn't get much responce, so I'll try here since this is an ignition board and all....

MSII v3 board, with v2.3 code

I am using the ignition driver circuit to directly run my coil. My question is if this has enough current capacity for a hot spark. I have this installed on a 2.8L turbo and have had really good luck when I run low boost. The problem is, low boost is no fun. Around 15psi and 4000rpm, the engine starts to miss. At 13psi, no miss anywhere. AF is a steady 12.5:1, so I am thinking it has to be ignition. I tried messing with the dwell settings and had a fair amount of luck.

Max dwell, 5.6ms
Max spark duration, .8ms

Increasing the dwell doesn't do any good, since at high rpm, the dwell HAS to be less than what I already have the max set at. Decreasing the max spark duration allows for more dwell, but seems to be reaching a point where the engine misses because it is too small. I am driving the stock coil ('83 Nissan 280zx turbo) which didn't seem to have any problems with ignition on the stock setup.

The problem seemed to get quite a bit better when I went back to driving the coil with the stock ignitor but there still seems to be a bit of ignition problems at high rpm. I have taken a couple of data logs but they don't seem to show anything ignition related. Any ideas?

If you want to run that much boost you need to upgrade your Ignition system .

First what size Plug Gaps are you using , anything over .030 and no stock
ignition system can fire the plugs with 15lbs. of boost .

The density of the air between the Plug Electrodes increases the voltage
required to jump the gap so much that the spark will try to find some other
easier way to get to ground , this means that your spark plug wires and
distributor cap must be in perfect condition at all times .

Of course it could also be that your coil just can't produce enough voltage
to jump the gap .

I would recomend that you get an MSD-6 Ignition controller .

You can still use the same output transistor in MS to control the MSD , but
you must do one realatively easy modification , you need to add a
"Pull-up" resistor inside your MS , (do a search for "Pull up resistor")
Then attach your MS ignition coil wire to the MSD White Wire (Points Wire).

This is also good because sometimes controlling your Coil directly from
inside MS can create noise and spike problems , making MS do weird things .

As long as your Cap and Wires are in perfect order , this will solve your problem .

...................Jim