The Hinwil-based outfit has struggled with the back end of its car since the start of the campaign, and it introduced a new rear wing and aerodynamic tweaks in China last weekend.
Although they helped Nico Hulkenberg lead the race early on from world champion Sebastian Vettel, he eventually slipped down the order to finish 10th.
Sauber team principal Monisha Kaltenborn says there were some encouraging signs coming out of its Shanghai performance, but much more was needed.
"We came here with the intention to introduce certain measures from what we saw in Malaysia," she told AUTOSPORT.
"We were not happy with that and we saw ourselves somewhere else. What we can see is that the measures we introduced are a step in the right direction.
"You cannot expect miracles, but they are at least a step in the right direction."
Kaltenborn says the biggest question mark after China was why Hulkenberg's pace dropped away in the closing stages of the race.
"Nico did a solid race and was competitive on both compounds," she said.
"Now we have to understand why in the last stint he was no longer competitive.
"It could be due to the temperature because of the ambient conditions. We have to look at that, as there was nothing to suggest that the car had been affected."
- Sports & Recreation
- Monisha Kaltenborn
- Nico Hulkenberg
- Sebastian Vettel