Honda has applied countermeasures to its power-unit control after a new turbocharger failed to remove Aston Martin's turbo-lag problems in Singapore, with further evaluation needed before the changes can be called a fix.

Shintaro Orihara, Honda's trackside general manager and chief engineer, explained at Austin that the stop-start layout and energy-management demands had left the drivers dealing with inconsistent acceleration. His comments were reported by PlanetF1.com following Thursday's media session.

The units were inspected at Sakura after the race. Honda had not found a major power-unit problem, but that did not make the car's response satisfactory.

At the moment, our control is not meeting driver demand, Orihara said.

Electrical deployment can help mask the delay, but Honda's explanation was that it cannot compensate for every operating condition. The work is therefore about controlling how the package responds, not simply installing another component and assuming the problem has disappeared.

Honda's own Friday report described a smooth day in Austin, with all planned test items completed and data work focused on drivability using driver feedback. Cooling requirements still needed to be settled after running in warm conditions.

That is useful progress through a test program, rather than a declaration that the underlying weakness has gone. In the FIA's Friday press conference, Adrian Newey also cautioned that Aston Martin and Honda need the chassis and power unit to work as a complete package.

The next measure is repeatable acceleration that gives the drivers confidence. A clean Friday is welcome; predictable response when it matters is the harder test.