Lotus technical director Nick Chester believes Renault's new energy recovery systems are responsible for "disturbing" its drivers Romain Grosjean and Pastor Maldonado.
Under the 2014 regulations, the augmented energy recovery systems require a brake-by-wire system in order to stabilize the car under braking while energy is harvested.
Due to the complexity of relationship between the energy and braking systems, combined with the problems Lotus have had with their Renault power units during testing, Chester admitted that it would take the Enstone team a considerable amount of time to perform at an optimal level this year.
"With the chassis itself the level of grip isn't too bad, even though we've lost a little bit of downforce," Chester told crash.net.
"The biggest problems are how the chassis works with the power unit and how the energy recovery system works. So there are some inconsistencies there which are making it very difficult for the driver to predict what he is going to get when he arrives at the corner.
"So the system is not doing exactly the same thing every time and that is disturbing the driver and losing us a lot of time."
Chester added that he has had no confirmation from Renault either way with regards to how long it would take the French manufacturer to get its power units working with its associated systems on a consistent basis.
"There are no fixed timescales. They are working very hard on it. I'm sure when they gather all the information after [the final] test for what has happened with all the teams we'll get another update of what is happening for Melbourne," Chester added.