Romain Grosjean said that he was worried about the impact of the latest updates on the handling of the Haas F1 car in Singapore.
Grosjean only managed to run four laps in total during Friday's two practice sessions, after suffering from low intake pressure in FP1 and then spinning rear-first into the barriers at the final corner in FP2.
"We had a problem with the power unit in the morning," Grosjean confirmed.
"In the afternoon we went out and straight away I didn’t feel comfortable in the car. We had some issues on the brakes, some stability problems and eventually spin the car and touched the rear wing, and the suspension was touched as well so we had to retire.
"Very tricky because I couldn’t do the back-to-back with the new parts. I don’t know what has changed on the car but it definitely wasn’t suiting me well today.
"The car was very weird in some places and very, very unpredictable so we don’t know if it’s related to updates or something else on top of other problems we had.
"I think we’ve got some doubts on some of the updates and what we should do. The guys are working now on the data, depending on how they come, I may decide to revert back on some stuff to try tomorrow."
Grosjean's team mate Esteban Gutierrez had a better time of it on Friday but also reported similar understeer issues to those experienced by Grosjean.
"I had the understeer," said Grosjean. "But I had some massive oversteer as well like the floor was giving up or something like that, which is why I spun. We just need to check everything and make sure there is no wrong parts on the car."
After one of the worst days in his Formula One career to date, Grosjean is now hoping for better fortunes ahead of him in Singapore this weekend.
"A clean rest of the weekend because we are really starting on the back foot with only having four timed laps today," he said when asked what he wanted to see on Saturday.
"I don’t know, I’m sure we’re going to find some tuning and get the car better for tomorrow and then try to see what we need to put on the car, keep the updates or revert back on some stuff.
"I hope we can get the updates to work better. Got a few ideas, let’s see tomorrow."
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