Chevy333

The astro van is a 2001 Coming behind someone's work. It did crank. It did run at idle only for a bit. I lost communication with them ecm. No lights on the cluster ( service engine soon etc.) No fuel pump relay power.
Apparently the ecm is not getting proper ground. Using a wire with clips at both ends I grounded the ecm case to the chassis and got back communication to the scan tool, fuel pump runs and the service engine light is back. I did not install the starter so I removed it. There were three wires attached. I removed the medium sized wire and now have proper ground without using the wire with clips to the ecm housing.

It starts and wants to run but I am aware the exhaust return to the intake is missing. This pipe

What happens when this pipe is not in place. The end on the manifold is crimped closed and the intake opening is open.