Max Verstappen said his lack of power during the Chinese Grand Prix was down to a spark plug issue creating a misfire on his Red Bull's Renault engine.
Verstappen was 19th fastest after suffering a loss of power during the opening session of qualifying in China, but will start at least two places higher after Romain Grosjean and Jolyon Palmer were given grid penalties.
Asked what happened, Verstappen said: "I think it's something to do with the coil from the spark plug, and that limited my qualifying. There was no power, I couldn't use the power modes so tried to do a lap but you are down a lot on power so it makes no sense really."
Red Bull boss Christian Horner added: "A very frustrating qualifying for Max, an unfortunate issue for him that looks engine related but hopefully can be salvaged without penalty for tomorrow."
Despite Verstappen failing to set a representative time, Red Bull was still off the pace of front runners Mercedes and Ferrari, with teammate Daniel Ricciardo 1.4s off pole position with no problems. Verstappen admits it may be a while before Red Bull are back on the pace.
"It will take some time. We have to be realistic, you cannot do it from one to another race. I also don't know how long it will take, we just have to wait and work hard.
"You feel it straight away [the first time in the car]. When it is difficult to set it up and difficult to put an easy lap time on the board then it's not right."
Asked whether the problem was finding the right set-up or just a lack of downforce, Verstappen added: "Both. I think it's both that we need to really work on to understand, because I think it's difficult to understand the changes we do. Compared to last year, we knew exactly what would happen to the car if we changed something, and that's not the case this year."