I'm not getting a lot of work done on my car this winter. Its been so mild I keep driving it every time I open up the garage to work on it.

I'm getting oily soot on the outside of my intake runners, clearly burping out from the joiner hoses at the manifold.

Why is it there, and is it something that I need to be concerned about?

Zach

Is the engine backfiring?

You have a wire unhooked. How old are those hoses? Are they hard and not sealing?

The wire is the grounding wire that you use to put a new firmware on the ECU.
The hoses may be 45 years old. They were on the 1.8 parts I got from Joe a decade ago when this engine was built.

If the engine is backfiring I don’t hear it. But it’s certainly possible.

Zach

Idk the numbers for the pressure changes that is experienced by the intake system, but it is all over the place. From idle with a good amount of vacuum to deceleration and the throttle plate closed with a larger amount of vacuum. Then there is also a reversion pulse when air is flowing back from the intake valve, under certain circumstances, toward the plenum. Just change those big hoses, or maybe clean up the soot and put some big zip ties or clamps on the hoses to see if the problem is eliminated.

That is a little strange?

Are you getting any kickback/resistance when cranking to start? What does your timing look like (cranking and timing table)

It would seem that a leak in one direction would also mean the possibility of a leak in the other direction. a vacuum leak.