I would have a meeting with this sponsor and have it open ended . Show that you care about this sponsor's needs and would like their advice and guidance. Ask questions.
It could be that they have trust issues or it may just be that this sponsor likes to maintain control of stuff .
So the impression you need to give them is you are working for them and for their best interests and that you can be trusted to deliver what they want from the project.
How do you think the project is progressing?
Are there any improvements that you suggest?
Are there any suggestions for information sharing that you would like me to provide for you or other stakeholders?
Are there any concerns that we need to address on this project?
As you know this project fits into the bigger program of works x y z. My suggestion is to create a business case to start another project and it would be great if you could champion that other project using your wide experience and insight . (If you can present a value proposition and show them another low hanging fruit that will benefit the organization, chances are they may start to investigate that other piece of work and not control your project too much. Alternately , If they ask you to investigate and report back, you know that they are trusting you anyways and you are in their good books :) )
After the meeting keep sending the sponsor a weekly update on the progress (if you do not do it already ) , covering such things as
What was done last week?
What is being done this week?
Whats the Project Spend to date?
Whats the Project forecast spend at Completion?
Tracking according to schedule/before/behind?
What are the key risks and Issues?
Think of something else that the sponsor keeps on asking you that may be covered as part of this report.
On the other hand, book other meetings with your team .Just say to the sponsor that you are doing some detailed planning on very low level deliverable and they are welcome to attend. Chances are , if they are not detail oriented or they don't know much about the technical deliverable, to save their ego, they won't attend and leave you alone.
Note that the sponsor is absolutely required to know and keep tabs on the High level project updates. If you have to use Information Overload to tire them out, do so .