Well, I see that im used to some old tech 
Here was my door timer. Wrote it ahed of the lesson 
if (PressurePlate->IsOverlappingActor(ActorThatOpens))
{
OpenDoor();
IsDoorOpen = true;
DoorTimer = DoorCloseDelay;
}
if (IsDoorOpen)
{
DoorTimer -= 0.001f / DeltaTime;
//UE_LOG(LogTemp,Warning,TEXT("Timer is %f"), DoorTimer );
if (DoorTimer <= 0)
{
CloseDoor();
IsDoorOpen = false;
}
}