Fernando Alonso and Honda at odds over 'healthy' engine problem

Fernando Alonso retired from the Azerbaijan Grand Prix with a power unit issue that both he and Honda cannot yet explain, after the Aston Martin driver reported a sudden and unexplained loss of straight-line speed.

Alonso had been engaged in a battle with Valtteri Bottas's Cadillac in Baku before his Aston Martin, fitted with a new-specification Honda engine for the weekend, encountered difficulties.

The Spaniard eventually pulled over, ending his afternoon not long after Lance Stroll in the other AMR26 had retired with a suspected water pressure issue.

Speaking to media, including RacingNews365, after the race, Alonso said the team had no choice but to stop the car.

"In the end, we had to stop. We suspect an engine problem," the two-time F1 drivers' champion said. "We had a lack of speed on the straight; it was anomalous, and we have to study it to see why."

Expanding on the issue, Alonso added: "I didn't see any alarm. Everything was working fine, but I started losing a lot on the straight, like 1.5 seconds. So it was, as I said, something anomalous."

Honda insists engine is 'healthy'

Honda's trackside general manager and chief engineer, Shintaro Orihara, offered a markedly different reading of the data after the race, insisting the power unit had shown no sign of trouble.

"In the data we have now, we have checked all the data; the engine is okay," Orihara explained. "We haven't found any issues in the data, but we will check carefully during the maintenance work, and also check the data back at the factory, and they will also check carefully.

"So, at the moment, we don't have any issues, but we will check carefully... the engine power, energy management, and maybe GPS waste."

Orihara also detailed the background to the new engine specification introduced for the weekend, revealing that Honda had already been forced into precautionary action once before Alonso's retirement.

The mismatch between Alonso's account of a clear performance loss on track and Honda's insistence that its data shows nothing wrong leaves the cause of the Baku retirement unresolved for now.

It comes amid a difficult campaign for the Honda partnership, which has been dogged since pre-season by drivability complaints, vibration issues and straight-line deficits, problems that led to a revised power unit specification being introduced at the Dutch Grand Prix, but that has done little to cure Aston Martin's troubles.

"We introduced the new engine, then in FP2, we found some irregular signals in our oil system," Orihara stated.

"Because of the new engine, we decided not to carry out [the run plan] to protect the new engine. We did an inspection after the session, and we found the root cause, and we replaced the part.

"Then, during FP3, qualifying and the race, we haven't seen any issues with the engine. So I believe the new engine is healthy, and that we can use the engine for the rest of the season."