Jerome D'Ambrosio admitted he was mystified by his lack of pace during qualifying for the Korean Grand Prix.
The Marussia Virgin driver finished in 22nd position nearly 1.5 seconds off the pace of team-mate Timo Glock as he struggled with a lack of grip. D'Ambrosio said he could not understand the reason for his car's poor speed.
"At the moment none of us really understand. The pace is not there, but it's not like one sector or like I'm losing somewhere. It's everywhere," D'Ambrosio said. "I think we have to get down to the bottom of this looking at the data, trying to understand. There's a feeling that there is something going massively wrong. My feeling is a lack of grip everywhere and that's it.
"But I don't want to go crazy on this. I think I just continue to do my job as best as I as can tomorrow and then we'll see. I'm sure we can improve and get to the bottom of it. Bad days happen and the most important thing is to understand where it's coming from."
He added: "The car balance was not the best I've had but not to explain 1.4 seconds. So it's very difficult to understand. This is the thing I can't explain at the moment. There are a couple of things we are looking at the moment and hopefully we can sort them out."
The Belgian said he will still give his all to try to have a good race on Sunday.
"Tomorrow I'll drive my heart out. It's a race and I'm a racing driver. Tomorrow is a new day and I will do everything I can to have a good race like in Suzuka, Singapore and Spa. That's my goal. To get in the car and drive my heart out."