Hi there alas my first post is a question for a mystifying issue I'm having.
I'm fairly new to Houdini so my limited knowledge has me banging my head against a wall.
I have a pyro set up which I am converting to a HDA to be used with Maya Houdini Engine.
But when I open the asset in Houdini all is expected the look of the Pyro sim is correct where a mushroom cloud rises and dissipates and a separate Pyro shock wave spreads out.
My issue is when I open the asset in Maya the look is not the same and no rising mushroom cloud occurs and its a mess, it looks totally different.

That is definitely unexpected behavior. Is this what you see immediately on loading the asset and playing back? Is it possible that the asset is loading from an older version in Maya? If you bring up the assetLibraryManager in Maya is it pointing at the version of the asset that you expect? Do you have disk caching on in the sim? Is it possible that it's running off an old cache when running in Maya? Did you export any of the simulation control parms to the asset - if so do they have the expected values in the Maya Attribute editor? Are you running at the same frame rate in Maya as in Houdini?

How complex is the pyro sim, in terms of numbers of grids, particles? Do all the pieces at least show up?

What happens if you just grab a fireball off the pyro shelf and make an asset out of it - does it play back as expected in Maya?

I didn't create the original set up, all I have done is to clean it up and get ti to work as an asset to be used within Maya 2016.
The unexpected look happens as soon as I play, I have no ‘Cache’ node in the pipe and I actually created a new simple HDA and deleted all file nodes etc or anything that writes to a specific path and the same strange look occurs.

What I have found is once I create the HDA and open in Houdini Engine within Maya the unexpected dynamics occur, If I go to ‘Debug asset’ in Maya H.Engine and it opens fresh in a new Houdini scene it does the same strange look.
Yet if I open the original Houdini scene before I compacted into a HDA etc, and delete all the nodes then import the HDA asset it works fine, so I'm thinking there is a setting in that particular scene that I am missing.

Generally off the shelf Pyro works as expected as I had converted another Pyro setup into a HDA and it worked fine, its just this particular set up. My beginner level in Houdini the difference is not immediately noticeable as all the settings in the Pyro solver are the same yet the look changes.

All I can think is a scale unit difference on this particular setup in Houdini compared to a clean scene, so I'll have a look today to see if that maybe the difference as like I said before, opening the HDA within Houdini on a fresh scene does the same unexpected look, yet opening in the scene where it was created produces the correct look.
If that's not it I'm stumped as to what it could be.

Ok looked at Houdini unit scale and nothing is different, I'm stumped!
Below images are 1 in the original scene with all nodes deleted and imported the HDA. The other shot a ‘new’ scene and imported the same HDA.

Attached isn't the main HDA I created from the set up, but a simple version as shown above where I have deleted the second Pyro sim, and the particles, and all the file nodes etc, just trying to see what could be causing the change in dynamics.
Also I have attached the set up before converting minus the particles and second Pyro sim.

Looking at the attached files, this does not seem to be a problem with Maya or Houdini Engine in particular, since the Test_Mushroom hda produces bad results in both Maya, and in Houdini. If I load the hip file and create a new hda from the pyro sim, the same problem happens in Houdini if I then do a File->new and create a new instance of the asset. Looking at the sim in more detail, there are warnings on a number of nodes (mostly the bypassed ones, but a few live ones too, might be worth checking for references outside the hda)

If there are other more complex hda's that work in Houdini but sim incorrectly in Maya then that could be a separate problem.

Thanks Juliap,

It managed to totally pass me by but there is a VOPSOP subnet which was the outside reference, I expanded and copied the contents outside of the subnet and it works now.
Reading up a bit VOPSOP is no longer used in H16 so tried first to rebuild with Point VOP but it doesnt work.
I'm a bit lost with that regard and need to study more, essentially from what I can tell the VOPSOP is taking the normals of the sphere and changing to velocity with random values. How would I do this with the Atribute VOP?
Sorry for the very basic questions I'm pretty new to Houdini.

VOP SOP is still around, but that's still a good question … Since this question is no longer Maya specific, it may be useful to repost the VOP and VEX related parts to the Technical Discussions forum, you'll get a lot more views.