Oyu started Sunday’s fifth round of the season on pole and led the opening 11 laps of the race before being passed by eventual winner Ritomo Miyata on the approach to Turn 1 at the end of lap 12 of 51.
From there, Oyu was quickly reeled in by third-placed Sho Tsuboi, and went off into the gravel at the first corner on lap 14 as he tried to hang on to second.
That off-track moment was the beginning of the end for Oyu, who came in for his mandatory pitstop and proved off the pace before finally giving up the ghost and parking up at the end of lap 30.
It marks his third successive failure to finish after he was rear-ended by Tomoki Nojiri at Suzuka, a clash that put both drivers in the barriers, and his contact with Sena Sakaguchi at Autopolis.
During the race, Oyu complained on the radio that the rear end of his TGM machine felt “weird”, suggesting a car issue had been to blame for his earlier excursion into the gravel.
Post-race, TGM team principal Kazuhiro Ikeda told Motorsport.com’s Japanese edition that adjustments made to Oyu’s car during warm-up resulted in the #53 machine bottoming out over Sugo’s bumpy long final corner, damaging the floor.
“In the eight-minute warm-up, the floor wasn’t scraping [the track] at all, so after hearing from the driver that he wanted more downforce and traction, the engineers decided to lower the ride height,” explained Ikeda.
“Finally this didn’t work. Especially in the last corner, there were puffs of smoke [from bottoming out], and little by little… eventually a hole opened up in the floor. So we lost downforce, and then the laptimes dropped off.
“It would have been good if we could have worked out the race set-up in Sunday morning practice, but the reason we failed was the adjustments we made in warm-up. It was the result of us being too aggressive.
“We had the feeling we could compete in warm-up, but to feel even more secure we put on even more downforce and we ruined the floor.”
Oyu hasn’t finished a race in the points since the opening round of the season at Fuji, although bonus points for his qualifying performances means he heads into the second half of the season joint-eighth in the drivers’ standings.
Ikeda remains confident that TGM can target a first win in the remaining four races of the year given the speed Oyu has shown.
“It was a wasted chance,” he said. “Racing isn’t easy. But if we can stay in this position, I think we will get another chance. And if we win once, we can build on that momentum.”
Oyu’s team-mate Cem Bolukbasi finished a lowly 17th after a costly crash in qualifying at Rainbow corner left him towards the back of the grid.