Honda look set to deliver a much-needed engine upgrade this weekend in Baku.
In Canada just over a week ago, McLaren chiefs admitted their frustration was at boiling point after the Japanese partner failed to deliver the upgrade as scheduled.
Honda's F1 chief Yusuke Hasegawa then said that he could not promise it would even be ready for the following race in Azerbaijan, but he has now confirmed that "some kind of improvement" in the combustion engine will be implemented for Baku.
"I don't know if you can call it specification three, but we'll definitely introduce something even if it is intermediate," he told Sportiva.
"If you improve the combustion engine, the temperature of the exhaust decreases by being more efficient, which reduces the energy recovered through the turbo and MGU-H, making it necessary to change these parts too.
"The situation is more complicated than people can imagine."
McLaren are yet to get on the board this season and sit bottom of the team rankings.