In about a week and a half I'll be running fuel from the MS II. On the ignition side, the Stock ECU will be controlling that end (for now). Is the missing link still required in this picture?

Yes, the PCM may negatively adjust the ignition timing if it senses a pressurized intake manifold. Either a fuel cut defender or missing link is recommended unless Megasquirt is controlling both fuel and spark.

Ah, I thought so. Thanks for the reply.

I am sorry but this is incorrect and proven to be wrong. The ECu will not adjust timing when it sees more than 4.63V for more than 2 seconds (positive pressure). I can name 1 member with a 97 that has run like this for more than 4 years without a Missing link or FCD.

When the ECU sees 4.63V or above on the Map sensor for more than 2 seconds it will throw a code. Since you do not have the ECU controlling injectors you will not notice the ECU hiccup or Cut fuel. If you decide to run a FCD, do it to keep one less code out of the ECU but do not entertain the false notion that the ECU will start to advance or retard timing based on it.

I have personally witnessed this phenomenon in a '96 2GNT. Perhaps it does not affect every model year, but it does occur.