When I was fixing the Adventra, I bought a Smoke Machine and found a number of leaks, it did come with a pump up bladder [like the one used for blood pressure machines].
And I bought the tube type one from eBay, that you can place on the exhaust outlet at the rear, and can be used on inlet manifolds.
The leaks I found -
- Where the brake booster connects to the manifold - I cut it back 20mm and refitted it
- The LH PCV pipe from the back of the LH cam cover, where is passes around the coolant filler was split - cut that section of the pipe out and fitted some rubber fuel line with small locking hose clamps.
- The Vapor solenoid pipe from the solenoid to the intake manifold [just behind the TB] - was split where is passes under the manifold from the LHS to the RHS, cut that section out, and used fuel line with some locking hose clamps.
And that fixed the intake side,
Then I tested the exhaust,
The leaks I found were at the the LHS engine pipe to the manifold - remove the engine pipe and cleaned both mating surfaces and refitted it
&
The RHS joint after the CAT - remove the rear mufflers, cleaned the mating surfaces and replaced both LHS & RHS gaskets [behind the CATS] , keeping in mind, this wasn't a easy task, because there is a lot more hardware under there on an Adventra, to cater for the bigger Trans, and Transfer case.
This might have nothing to do with your issue,
But the other day I filled the Adventra up, and I mean TOPPED IT UP to the filler, I then noticed petrol drip out under the back wheel,
So I suspect the breather pipe may be split or similar, which may possibly cause the loss fuel on a left hand turn,
or it may cause it to evaporate.
Hence less fuel in the tank, but the DTE thinks its used more, so the reading of used fuel is higher.
That said, I am going to let it run down to 1/4 tank, and used the smoke machine on it.
I am assuming you received smoke liquid with it,
If you did, and run out of it, you can use Baby Oil in the machine, and works great,
The disadvantage with baby oil, is the baby oil smells a bit unusual when its heats up in the machine.
Funny story -
My nephew wanted his car smoke tested, and so he offered to buy the baby oil at the local supermarket,
Apparently the girl that served him, knows him through a mutual friend,
And the comment was
"So what are you going to use this for"
he tried to explain, but he got a bit embarrassed.

So its a bit of a family joke now.

hahahahaha