Pedro de la Rosa qualified just seventeenth in Shanghai.
"We lack top speed," said the Sauber driver.
After innovators McLaren, the Swiss team had been the first to implement an F-duct solution, but it was not running on the C29 in China.
"We had to put the standard wing back on. It worked on Friday but not today," the 39-year-old told Spain’s Marca newspaper on Saturday.
After Ferrari, Mercedes and Williams also experimented with F-duct solutions in China, it is expected that the bulk of the remaining established teams - Renault, Red Bull and Force India - could debut wing-stalling systems in Spain next month.